IC-NRLF 
 
 
 
 
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 New York: D. APPLETON & CO., 72 Filth Avenue. 
 
THE INTERNATIONAL SCIENTIFIC SERIES 
 
 MICROBES 
 
 FERMENTS AND MOULDS 
 
 BY 
 
 E. L. TROUESSART 
 
 WITH ONE HUNDRED AND SEVEN ILLUSTRATIONS 
 
 NEW YORK 
 D. APPLETON AND COMPANY 
 
 72 FIFTH AVENUE 
 1895 
 
Main Lib. 
 
 Afrit, Dwt. 
 
 -T6 
 
 SIOLOGY 
 
 LIBRARY 
 
 G 
 
UHI71ESITT 
 
 PREFACE. 
 
 THE number of works which treat of microbes is 
 already considerable, but they have all been written 
 for a special public of physicians or naturalists, and 
 imply that the reader is familiar with the ideas 
 already established on pathology or on cryptogamic 
 botany. 
 
 Although the science of microbes is of recent 
 origin, it has made immense progress in the course of 
 a few years. It is, moreover, essentially a French 
 science, since it is owing to Pasteur's admirable 
 labours, as well as to his solid genius, aided by the 
 faith and energy of his disciples, that this science 
 has been able to overcome the prejudices of ages, and 
 to penetrate into the very heart of the ancient theory 
 of medicine, so as to transform and regenerate it. 
 
 Every one now speaks of microbes, yet few of those 
 who make use of the term have any clear conception 
 
vi PREFACE. 
 
 of the beings in question, or could give an exact 
 account of the function which microbes fulfil in 
 nature. And yet this function concerns us all. 
 
 The man of the world who desires to take part in 
 a scientific discussion; the lawyer who has to treat of 
 a question of hygiene in the presence of experts ; the 
 engineer, the architect, the manufacturer, the agricul- 
 turist, the administrator all have to consider such 
 questions, and they will find in this work clear and 
 precise notions on microbes, notions which they would 
 find it difficult to glean from books designed for 
 physicians and professional botanists. 
 
 The questions of practical hygiene, those which 
 concern domestic economy, agriculture, and manufac- 
 tures, and which are connected with the study of 
 microbes, must especially demand attention. These 
 are pertinent questions in such a book as this. There 
 is a certain danger in vulgarizing notions of medicine, 
 strictly so called; but it can only be beneficial to 
 make every one acquainted with the precepts of hy- 
 giene, which cannot become popular until they have 
 penetrated into the habits and routine of national 
 life. 
 
 There is much to be done before modern society 
 is practically on a level with the achievements of 
 science; many prejudices must be uprooted, and many 
 
PREFACE. Vll 
 
 false notions must be replaced by those which are 
 sounder and more just. 
 
 For this reason, we have endeavoured to make 
 this work intelligible to all. It may be read with 
 profit by those who possess the elementary notions 
 of natural science which are included in the course 
 of primary instruction. We therefore hope that the 
 volume may find a place in the libraries of secondary 
 instruction, and in public libraries. 
 
 Although the work is not specially intended for 
 physicians, yet practical men may not be indisposed 
 to glance at it : it may, at any rate, serve as an intro- 
 duction to the much more learned works of Cornil 
 and Babes, of Duclaux, Klein, Koch, Sternberg, etc. 
 We have given an important place to the botanical 
 question, which is too often neglected in works on 
 microbian pathology. From this point of view, the 
 narrow bond which connects bacteria with ferments 
 and moulds has to some extent marked out the plan 
 we have adopted; namely, that of passing from the 
 known to the unknown, from what is visible with the 
 naked eye to that which is only visible with the aid 
 of the microscope. 
 
 ANGERS, September 10, 1885. 
 
THflTBRSITT 
 
 TABLE OF CONTENTS. 
 
 INTRODUCTION. 
 
 M4M 
 
 MICROBES AND PUOTISTA ... ... ... .., ... 1 
 
 CH A FT Ell I. 
 
 PAHASITIC FUNGI AND MOULDS ... ... ... ... 9 
 
 I. General remarks on fungi ... ... ... 9 
 
 II. Babidiomycetes : uredinese, the rust of wheat and gra.-sus 14 
 
 III. Ascomycetes : ergot of rye; mould of leather and dried fruit 20 
 
 IV. Oomycetes, mucormese, or moulds, strictly so called ; pero- 
 
 nosporse; potato-fungus ... ... ... 27 
 
 V. Parasiiic fnngi of the vine: oi'dinm, mildew, etc. ... 32 
 
 VI. Habitat and station of parasitic fungi: their destructive 
 
 action ... ... ... ... ... 43 
 
 VII. Parasitic fungi of insects, considered as auxiliaries to man 47 
 
 VI I [. Muscjirdin, or disease of silkworms ... ... ... 50 
 
 IX. Parasitic fungi of the skin and mucous membrane of man 
 
 and other animals ... ... ... ... 51 
 
 CHAPTER II. 
 
 FKKMEXTS AND ARTIFICIAL FERMENTATIONS ... ... 6(5 
 
 I. Definition of fermentation... ... ... ... GO 
 
 II. Vegetable nature of ferments, or yeasts ... ... ... 72 
 
 III. Ferments of wine ; alcoholic fermentation ... ... 74 
 
 IV. Beer-yeast ... ... ... ... ... ... 78 
 
 V. Concerning some other fermented drinks ... ... 82 
 
 VI. Yeast of bread ... ... ... ... ... &i 
 
X CONTENTS. 
 
 CHAPTER III. 
 
 PAGE 
 
 MICROBES, STRICTLY so CALLED, OR BACTERU ... ... 85 
 
 I. The vegetable nature of microbes ... ... 85 
 
 II. Classifies tio i of microbes, or bacteria ... ... ... 91 
 
 III. The microbe of vinegar, and acet c fermentation ... 95 
 
 IV. The microbes which produce the diseases of wine ... 98 
 V. The microbe of lactic fermentation ... ... ]05 
 
 VI. The ammoniacal fermentation of urine ... ... 107 
 
 VII. Butyric fermentation of butter, cheese, and milk ... 109 
 
 VIII. Putrid fermentation, game-flavour ... ... ... 112 
 
 IX. Aerobic and anaerobic microbes ... ... ... 117 
 
 X. The microbes of sulphurous waters ... ... ... 119 
 
 XT. The microbes which produce saltpetre ... ... 121 
 
 XII. The microbes which destroy building materials ... 123 
 
 XIII. The microbes of chalk and coal ... ... ... 124 
 
 XIV. Chromogeiiic microbes ... ... ... ... 126 
 
 XV. The microbe of baldness ... ... 131 
 
 CHAPTER IV. 
 
 THE MICROBES OP THE DFSEASES OP DOMESTIC ANIMALS ... 132 
 
 I. Anthrax, or splenic fever ... ... ... 1:52 
 
 II. Vaccination for anthrax ... ... ... ... 139 
 
 III. Fowl cholera ... ... ... ... ... 142 
 
 IV. Swine fever ... ... ... ... ... 143 
 
 V. Some other diseases peculiar to domestic animals} ... 144 
 
 VI. Rabies ... ... ... ... ... ... 147 
 
 VII. Gland.-rs ... ... ... ... ... 149 
 
 VIII. Pebriue and flucherie, two diseases of si. k worms ... 150 
 
 CHAPTER V. 
 
 THE MICROBES OF HUMAN DISEASES ... ... ... 156 
 
 I. Microbes of the air, the soil, and water ... ... 156 
 
 IJ. Microbes of the mouth and digestive canal in a healthy 
 
 man ... ... ... ... ... ... 172 
 
 III. The virulent microbe of human saliva ... ... 176 
 
 IV. The microbes of dental caries ... .*. ... 177 
 V. The microbes of intermittent or marsh levei s ... 179 
 
 VL The microbes of recurrent fever and yellow fever ... 187 
 
CONTENTS. XI 
 
 PAGE 
 
 VII. Typhoid fever and typhus ... ... ... 191 
 
 VIII. The microbe of cholera ... ... ... ... 195 
 
 IX. Eruptive fevers : scarlatina, small-pox, measles, etc. 209 
 
 X. The microbes of croup and whooping-cough ... ... 215 
 
 XI. The microbes of phthisis and leprosy 
 
 XII. The microbe of pneumonia ... ... ... ... 229 
 
 XIII. Some other diseases due to microbes ... ... 230 
 
 X IT. The microbe of erysipelas ... ... ... ... 232 
 
 XV. The microbes of pus, septicemia, etc. ... ... 2.-J4 
 
 XVI. The microbes of other diseases, clue to wounds ... 236 
 
 XVII. The mode of action of pathogenic microbes : ptomaines 237 
 
 CHAPTER VI. 
 
 PROTECTION AGAINST MICROBES ... ... ... ... 242 
 
 I. Antiseptic treatment of wounds: Gue'rin's protective treat- 
 ment; Lister's dressing ... ... ... ... 242 
 
 II. Hygiene of drinking- water : water fiee iroin microbes; 
 
 Cumberland filter ... ... ... ... ... 245 
 
 CHAPTER VII. 
 
 LABORATORY RESEARCH, AND CULTURE OK MIOUOBES ... 258 
 
 CHAPTER VIII. 
 
 POLYMORPHISM OF MICROBES ... ... ... ... 272 
 
 CHAPTER IX. 
 
 CONCLUSION ... ... ... ... ... ... 285 
 
 The Miorobian T. c-ory compared with other Theories set forth to 
 
 explan the Origin of Contagious Diseases ... ... 285 
 
 APPENDIX. 
 
 A. Terminology of Microbes ... ... ... ... 301 
 
 B. Micrococcus of phosphorescence ... ... ... 304. 
 
 C. Diseases of plants caused by bacteria ... ... ... 305 
 
 D. Ptomaine of the microbe of fowl cholera ... ... 306 
 
 K. Cesspools. System of conveying everything to the sewers 306 
 
 F. Sewers of Paris and the Plain of Gennevilliers ... 3()7 
 
 G. Useful microbes ... ... ... ... ( 30g 
 
 H. Ptomaines of fish .., ... ... 308 
 
MICROBES, FERMENTS, AND MOULDS, 
 
 INTRODUCTION. 
 
 MICROBES AND PROTISTA. 
 
 MICROBES are the most minute living things which 
 the microscope permits us to see distinctly, so as to 
 study their organization. They are for the most part 
 invisible to the naked eye, and even by the aid of a 
 simple lens. In order to form an exact idea of their 
 forms and structure, we require the strongest magni- 
 fiers of modern instruments, which enlarge the object 
 500, 1000, and even 1500 diameters. 
 
 The word microbe has been recently introduced 
 into the French language ; it did not exist eight years 
 ago, and for this reason it will be sought for in vain 
 in most dictionaries. It was under the following cir- 
 cumstances that this term, now in such general use, 
 was invented by Sedillot, an eminent surgeon, whose 
 recent death is deplored by France. 
 
 Those naturalists who have studied the most 
 2 
 
2 MICROBES, FERMENTS, AND MOULDS. 
 
 minute living things have at all times been at a loss 
 to decide whether they have had to do with animals 
 or plants. There can be no such doubt when we com- 
 pare a tree of which the roots are fastened in the soil 
 with a quadruped which moves freely on its surface. 
 But these are highly developed forms, the one in the 
 vegetable, the other in the animal kingdom. The 
 lower representatives of the two kingdoms are, on 
 the other hand, often so much alike as to baffle the 
 most experienced naturalist. The animals which are 
 assigned to the order of Zoophyta, or animal -plants, 
 have, as the name indicates, a form which led them to 
 be for a long while regarded as plants ; many of them 
 are fastened to the bottom of the sea or to rocks as if 
 by actual roots, and, when superficially examined, their 
 movements do not differ much from those which may 
 be produced in true plants, as, for instance, in the 
 mimosa. 
 
 Many of the lower plants, belonging to the groups 
 of Algae and Fungi, live in the water without being 
 fixed by roots ; many are animated by more or less 
 apparent motion, at any rate during part of their 
 existence, so that it is often somewhat difficult to dis- 
 tinguish them under the microscope from those beings 
 which are generally called Infusoria, and which are 
 true animals. 
 
 Hence it follows that the boundary between the 
 animal and vegetable kingdoms remains indefinite, 
 and that many of those microscopic organisms which 
 
OF TOT 
 
 foil? W 
 
 MICROBES A 
 
 we have now to consider, may be assigned indifferently 
 to one or the other kingdom. 
 
 Bory de Saint- Vincent, a naturalist belonging to 
 the early part of the century, and after him Hseckel, 
 have attempted to evade this difficulty by creating 
 between the animal and vegetable kingdoms an inter- 
 mediate kingdom, which they have named Protista, 
 indicating thereb3^ that it includes the first animals 
 which in the geological ages appeared on the earth's 
 surface. This kingdom of Protista includes the fol- 
 lowing groups, starting from the simplest and going 
 on to those which are more complex : 
 
 *1. Monera (or Microbes, strictly so called; Schizouiycetes, Bac- 
 teria, Vibriones, ( tc.). 
 
 2. Amorphous Rhizopoda (or Amoebae). 
 
 3. Grega.'-imdae. 
 
 4. Flagellata. 
 
 5. Catallacta. 
 
 6. Infusoria. 
 
 7. Acinetae. 
 
 8. Labyrinthulae. 
 
 9. Diatomace^B. 
 *10. Myxomycetes. 
 *11. Fungi. 
 
 12. Thalamophnra (Foraminifera or Rhizopoda with a calcareous 
 
 skeleton). 
 
 13. Radiolaria (or Rhizopoda with a silicious skeleton). 
 
 The groups marked with an asterisk are those 
 which we propose to study in this work. For the 
 most part, the organisms assigned to them resemble 
 plants in their general characters. They are parasites 
 which derive their nutriment from other living beings. 
 
 For this reason, many of these organisms are the 
 
4 MICROBES, FERMENTS, AND MOULDS. 
 
 cause of the more or less serious diseases which affect 
 animals or plants. Naturalists who regard these para- 
 sites as animals have termed them Microzoaria (from 
 two Greek words signifying small animals). Those 
 who regard them as plants have called them Micro- 
 phyta (small plants), and it is still disputed which 
 term is the most applicable to them. In other words, 
 it is still undecided whether they should be classed in 
 the animal or vegetable kingdom. 
 
 It was at the Paris Academy of the Sciences, on 
 the llth of March, 1878, that Sedillot took part in one 
 of the probably interminable discussions between the 
 advocates of the Microzoaria and those of the Micro- 
 phyta, and he suggested, with the critical sense for 
 which he was distinguished, the word microbe, to 
 which it appeared to him that every one could give 
 their assent. 
 
 In fact, the word microbe, which only signifies a 
 small living being, decides nothing as to the animal 
 or vegetable nature of the beings in question.* It has 
 been adopted by Pasteur, and approved by Littre, 
 whose competence to decide on neologisms is generally 
 admitted ; it has been in common use in France for 
 the last four or five years, and may now be regarded 
 as definitively adopted into the French language. 
 
 This word has not yet been fully introduced into 
 
 * Be*champ terms microbes microzyma, or small ferments, since the 
 chemical reactions which result from their vital activity are generally 
 fe i mentations. 
 
MICROBES AND PROTISTA. O 
 
 the English and German languages. In order to in- 
 dicate the organisms which produce diseases, they 
 make use of the word Bacteria, which is only the 
 name of one of the peculiar species assigned to this 
 group, and the one with which we have been longest 
 acquainted. In this case, the name is generalized and 
 applied to an entire group. 
 
 The Italian authors who have been recently occu- 
 pied with the study of microbes have on their part 
 adopted the name Protista, proposed by Hseckel, and 
 of which the sense, although not the etymology, is 
 almost the same as that of the word microbe. 
 
 In reply to the question whether there is any real 
 advantage in establishing an intermediate kingdom 
 of Protista between the two organic kingdoms of 
 animals and plants, we must answer in the negative. 
 This third organic kingdom only serves to render 
 the structure of our modern classification more com- 
 plex ; and it includes, as may be seen from the list 
 given above, a collection of very heterogeneous groups, 
 which it would be more simple to leave in one or the 
 other kingdom. We should, in our opinion, approxi- 
 mate more closely to Nature's plan by only admitting 
 two great kingdoms : the organic kingdom, which 
 includes plants and animals ; and the inorganic king- 
 dom of minerals. The organic kingdom should then 
 be divided into two sub-kingdoms, animals and 
 plants, of which microbes or protista, or whatever 
 else they may be called, should form the connecting 
 
6 MICROBES, FERMENTS, AND MOULDS. 
 
 link, and testify to the common origin of the two 
 great organic kingdoms. 
 
 However this may be. we shall make use of the 
 word "microbe" as the general designation of all 
 the minute organized beings which are found on the 
 borderland between animals and plants. We shall 
 presently show that in the majority of cases these 
 beings may be regarded as true plants, and this is at 
 present generally admitted by most naturalists. 
 
 Part played by Microbes in Nature. The part 
 played by microbes in nature is an important one. 
 We find them everywhere ; every species of plant has 
 its special parasites, and this is also the case with our 
 cultivated plants with the vine, for example, which is 
 attacked by more than a hundred different kinds. 
 These microscopic fungi have their use in the general 
 economy of nature ; they are nourished at the expense 
 of organic substances when in a state of putrefac- 
 tion, and reduce their complex constituents into those 
 which are simpler into the soluble mineral substances 
 which return to the soil from which the plants are 
 derived, and thus serve afresh for the nourishment of 
 similar plants. In this way they clear the surface of 
 the earth from dead bodies and feecal matter ; from all 
 the dead and useless substances which are the refuse 
 of life, and thus they unite animals and plants in an 
 endless chain. All our fermented liquors, wine, beer, 
 vinegar, etc., are artificially produced by the species 
 of microbes called ferments; they also cause bread 
 
MICROBES AND PROTISTA. 7 
 
 to rise, and from this point of view they are pro- 
 fitable in industry and commerce. 
 
 But in addition to these useful microbes, there are 
 others which are injurious to us, while they fulfil 
 the physiological destiny marked out for them by 
 nature. Such are the microbes which produce dis- 
 eases in wine ; most of the changes in alimentary and 
 industrial substances; and, finally, a large number of 
 the diseases to which men and domestic animals are 
 subject. The germs of these diseases, which are only 
 the spores or seeds of these microbes, float in the air 
 we breathe and in the water we drink, and thus 
 penetrate into the interior of our bodies. 
 
 Hence we see the importance of becoming acquainted 
 with these microbes. Their study concerns the agri- 
 culturist, the manufacturer, the physician, the pro- 
 fessor of hygiene, and, indeed, we may sa,y that it 
 concerns all, whatever our profession or social position 
 may be, since there is not a single day, nor a single 
 instant, of our lives in which we cannot be said 
 to come in contact with microbes. They are, iu 
 fact, the invisible agents of life and death, and this 
 will appear more plainly from the special study we 
 are about to make of the more important among 
 them. 
 
 Since it is easier to know and observe beings which 
 are visible to the naked eye, we shall first speak of 
 fungi that is, of the larger microbes, with whose 
 habits and organization we are also best acquainted. 
 
8 MICROBES. FERMENTS, AND MOULDS. 
 
 We will then go on to the study of the more minute 
 ferments ; and finally to that of bacteria (Schizophyta 
 or Schizomycetes), which are, strictly speaking, mi- 
 crobes, and which only become visible with the aid of 
 the microscope. 
 
CHAPTER I 
 
 PARASITIC FUNGI AND MOULDS. 
 
 I GENERAL REMARKS ON FUNGI. 
 
 EVERY one is acquainted with the field and forced 
 mushrooms, two varieties of one and the same species, 
 wild or cultivated, and often seen at table. It is less 
 generally known that the truffle is also a fungus ; 
 and that the large class of fungi includes moulds and 
 many parasites which are more or less microscopic, 
 which live at the expense of wild and cultivated 
 plants, and attack animals and also the human subject. 
 Fungi are among the lower plants, and differ from 
 higher orders in their mode of life. It is well known 
 that the large majority of plants are not nourished only 
 by absorbing the mineral salts which, in a state of 
 solution, their roots derive from the soil, but also, and 
 chiefly, by decomposing the carbonic acid of the air, 
 assimilating the carbon which, as cellulose, enters 
 into the composition of all their tissues, and giving 
 forth nure oxygen to the air. 
 
10 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 This function is not, as it was formerly erroneously 
 supposed, a respiration in the inverse form from that 
 of animals. All plants without exception breathe 
 like animals by absorbing oxygen. The assimilation 
 of carbon is a true nutrition, and as the decomposition 
 of the carbonic acid gas which results from this assi- 
 milation sets free a much larger quantity of oxygen 
 than the plant requires for itself, it was for a long 
 while believed that plants really breathed the car- 
 bonic acid gas of the air, in the inverse method to 
 that of animals. 
 
 Fig. l.Affaricat in different stages of development : 2, 3, a vertical section showing 
 the formation oftlie head. The hyphee of the inyceduiu are shown in the lower 
 part of the figure. 
 
 The assimilation of carbon is effected by the leaves 
 and green parts of plants ; the green, granular sub- 
 stance termed chlorophyll, which solely gives them 
 this colour, as may be shown by the microscope, and 
 which alone subserves this function cf nutrition. 
 Fungi, however, have no leaves nor other green parts ; 
 that is, they have no chlorophyl. They derive the 
 cellulose which they contain, as well as all the sub- 
 stances by which they are nourished, either from 
 
PARASITIC FUNGI AND MOULDS. 11 
 
 other plants, or from animals and from the organic 
 substances which are decomposing in the soil, such 
 as dung and dead bodies. So that it may be said 
 of fungi, that they subsist like animals by devouring 
 plants or other animals ; not like higher plants, which 
 derive their nutriment from the soil or the air, and 
 owe nothing to other living beings. 
 
 It is for this reason that some naturalists have 
 regarded fungi as animals, and have classed them in 
 the animal kingdom. We have seen that Hseckel 
 and the naturalists of his school have assigned them 
 to the kingdom of Protista. 'But setting aside their 
 mode of nutrition, which is likewise found in plants of 
 a higher organization, such as the Orobranchece and 
 some of the Orchidacece, fungi really exhibit all the 
 characters of plants, and as such we shall here con- 
 sider them, although they are plants of a peculiar 
 and very low type. 
 
 The class of fungi may be defined by saying that 
 they are plants devoid of stems, leaves, and roots ; that 
 they consist only of cells in juxtaposition, devoid of 
 chlorophyl. They never bear a true flower, and are 
 simply reproduced by means of very minute bodies, 
 generally formed of a single cell, which is called a 
 spore, and which represents the seed. 
 
 In fungi of the highest type, such as that commonly 
 known as the edible mushroom, the part which we 
 eat and call the umbrella represents the flower or 
 floral peduncle of other plants, and is in reality only 
 
12 
 
 MICKOBES, FERMENTS, AND MOULDS. 
 
 the support or covering of the spores, which are fixed 
 on the radiating lamellae that may be seen on in- 
 verting the umbrella (Figs. 2 and 3). This umbrella 
 or floral peduncle is the only part of the plant which 
 appears above the soil, or the organic substances 011 
 which the fungus grows. 
 
 But the really essential part of the plant is that 
 
 Fig 2 Section cf one of the lamella? 
 Oi the umbrella of Agaricus c: 
 a, b, spores of the hymenium 
 (slightly magnified). 
 
 Fig. 3 Spores of the hymen ium, greatly 
 magnified, and resting on their supports 
 or uasidvs, a. 
 
 which does not appear on the surface; namely, the 
 white filaments or kyphcB which creep along the soil, 
 the manure, or whatever supplies the nutritive matter, 
 and which represent at once the root, the stem, and the 
 branches of the plant ; this part is termed the mycelium. 
 We shall presently see that many of the lower fungi 
 are without the organ we have called the umbrella, and 
 which botanists term the hymenium or organ of repro- 
 duction, and consequently consist only of mycelium. 
 
PARASITIC FUNGI AND MOULDS. 13 
 
 In this case, the spores or seeds are developed in the 
 cells of the mycelium itself. 
 
 This latter mode of reproduction also occurs in the 
 higher fungi, which therefore possess two modes of 
 reproduction and two kinds of spores : exogenous 
 spores, which are externally developed, as we see on 
 the hymeriium (Fig. 2) ; and endogenous or internal 
 spores, which are developed in 
 the mycelium (Fig. 4). These 
 spores not only differ in the 
 site of their origin, but also in 
 their form, size, structure, and 
 in the end they fulfil in the 
 reproduction of the fungus. 
 There are in many cases several 
 forms of exogenous spores. 
 
 . . , . Fig. 4. Endogenous spores from 
 
 Classification Of Funqi. the myci-lium of Agaricus 
 
 J (much magnified). 
 
 The nature of the spores, and 
 
 the very varied mode of reproduction, have led to 
 the classification of fungi in a certain number of 
 groups, of which we need only cite the most im- 
 portant, and those which chiefly concern our present 
 point of view. Such are 
 
 1. The Hymenomycetes. 
 
 2. The Basidiomycetes. 
 
 3. The Ascomycetes. 
 
 4. The Oomycetes. 
 
 Each of these groups is subdivided into several 
 sections or families. Ferments and Schizomycetes, or 
 
14 MICROBES, FERMENTS, AND MOULDS. 
 
 microbes, properly so called, are still often assigned to 
 the class of fungi. We shall speak of them separately, 
 and give our reasons for distinguishing them from 
 true fungi. 
 
 Hymenomycetes are the fungi which possess the 
 hymenium or umbrella; all the edible species are 
 included in this class, together with a great number 
 of extremely pokonous species. They are generally 
 of considerable size, and only a few among them are 
 true parasites ; they do not, therefore, enter into the 
 plan of this work, and, in spite of the interest they 
 present, we shall content ourselves with the brief 
 notice of them we have just given. The other groups 
 must, however, detain us longer. 
 
 II. THE BASIDIOMYCETES : UREDTNE^, THE RUST OF 
 WHEAT AND Gn ASSES. 
 
 The name of cereal rust is given to a parasitic 
 affection caused by a minute microscopic fungus which 
 is developed on the leaves of wild and cultivated 
 grasses. This rust appears in the form of orange 
 patches, which gradually spread over the blades of 
 wheat and other grasses, and its common name is 
 due to this colour. Many of the plants belonging 
 to other families are attacked by analogous parasites, 
 and these fungi are all assigned by naturalists to 
 the genus Uredo, and to the family of the Basidio- 
 mycetes or Uredinece. 
 
PARASITIC FUNGI AND MOULDS. 
 
 15 
 
 Basidiomycetes have no endogenous spores, but 
 they may have as many as four forms of exogenous 
 spores. This is the case with the rust of wheat, 
 termed by naturalists Uredo or P-uccinia graminis, 
 which appears in the spring on the blades of this 
 plant. The patches of rust are covered with a fine 
 dust, which, under the microscope, is seen to consist 
 of small elongated bodies of a reddish brown, resting 
 on a filament; these are the first 
 spores of the fungus, and are 
 termed uredospores (Fig. 5). If 
 they are scattered over a blade 
 of wheat which was previously 
 healthy, they germinate by means 
 of a hypha of mycelium, which 
 penetrates the leaf and develops 
 a fresh patch of rust. In harvest- 
 time the patches are of a darker, 
 almost black shade, owing to the 
 development of a second kind of 
 spore. These are pear-shaped, 
 divided in two, with an enveloping 
 membrane of considerable thickness ; they are called 
 teleutospores (Fig. 5). 
 
 Teleutospores cannot germinate on a healthy blade 
 of wheat, and consequently do not communicate rust. 
 They may remain through the winter on thatch 
 or wheat straw, awaiting the ensuing spring, and 
 even then they cannot be developed upon a blade 
 
 Fig. 5. Part of a patch of 
 Puce in ia graminis, taken 
 from a blade ot wheat, and 
 displaying several uredo- 
 spores and one teleutofpore. 
 (.much magnified). 
 
16 MICROBES, FERMENTS, AND MOULDS. 
 
 of wheat, but only upon the leaves of another plant, 
 the barberry. 
 
 Borne by the dew or by a drop of rain on to the 
 young leaves of the barberry, the teleutospores germi- 
 nate, and form reddish-brown patches which affect 
 both sides of the leaf. On its lower surface the 
 spores are smaller, and are termed spermata; their 
 function is not thoroughly understood. The larger 
 spores on the upper surface are called cvcidiospores 
 (Fig. 6), and with these we are more concerned, since 
 
 Fig. 6. Section of a barberry-leaf bearing two cecidiospores, more or less developed, 
 of I'uccinia graminis ^much magnified). 
 
 they are destined to return to the wheat, rye, or other 
 grasses, in order to reproduce the original rust. 
 
 When they are placed on a blade of one or 
 other of these grasses, the oeoidiospores germinate at 
 once, and it is soon covered with patches resembling 
 those of the preceding year; when these patches are 
 numerous, they dry up the blade and destroy the ear. 
 
 Hay and straw affected by rust should never be 
 given to animals as food, since such food may produce 
 disease. 
 
 Thus it appears that Puccinia graminis presents 
 the phenomenon of alternation of generations ; that is, 
 
PARASITIC FUNGI AND MOULDS. 17 
 
 the complete development of the fungus is only effected 
 by its transference from one plant to another. This 
 phenomenon may be frequently observed in animal 
 and vegetable parasites, and it seems to be designed 
 in order to secure the preservation of the parasitic 
 species, by permitting it to grow on two plants in 
 succession, of which the development occurs at different 
 periods of the year ; such is the case with the barberry, 
 which is developed in early spring, while wheat is 
 developed in summer. For a long while it was 
 believed that (Ecidium berberidis, Uredo linearis, 
 and Puccinia graminis were so many distinct 
 species; but it is now known, as we have stated, 
 that they are only three successive phases of the 
 development of a single species.* 
 
 Other Uredinece, constituting the modern varieties 
 of Ustilago and Tilletia, are more apt to affect the 
 ears of wheat and other grasses. This disease is termed 
 by agriculturists smut or caries (Uredo carbo or 
 Ustilago segetum, and Tilletia caries). The diseased 
 grain merely appears to be of a somewhat darker 
 colour, but on pressing it between the fingers, there 
 issues from it a blackish, oily pulp, which smells 
 like rotten fish. Bread made from the flour of such 
 corn has an acrid and bitter taste, and although it 
 does not Sppear to be directly injurious to health, 
 
 * So, again, (Ecidium rhanmi (Ncrprun or Bonrdaine) produce 
 Jliedo rubiyo-vera and Puccinia corouata of wheat and oats. (See 
 Fig. 7.) 
 
18 MICROBES, FERMENTS, AND MOULDS. 
 
 it cannot be regarded as fit for food. The dust 
 arising from these fungi often produces in threshers 
 in a barn an iriitating cough, which ceases when 
 they are no longer subject to the exciting cause. 
 
 The verdet, or, as the Italians call it, verderame of 
 maize is due to the presence of the same parasite 
 (Ustilago seyetum,Uredo carbo, or Sporisorium maidis) 
 on the grains of maize, and fur a long while it was 
 believed to produce pellagra, a common disease among 
 the peasants who live on maize. It is now known 
 that pellagra is due to the growth of another fungus, 
 much resembling the ergot of rye, of 
 which we shall speak presently. 
 
 Other species of Uredinece attack 
 sorghum, rice, etc., and, indeed, very 
 many plants are affected by parasitic 
 fungi belonging to the genus Puccinia 
 and to allied genera, and it is probable 
 
 that the y almost a11 Present the phe- 
 nomenon'of alternation of generations. 
 A simple means of freeing our fields from the rust 
 of wheat is indicated by what we now know of the 
 alternation of generations which ensures the propaga- 
 tion of this fungus. We must destro} r all the barberry 
 bushes which are found in the vicinity of cornfields. 
 Popular opinion, although ignorant of the phenomenon 
 of alternation of generations, has long regarded the 
 neighbourhood of the barberry as the principal cause 
 of the rust of cereals. 
 
PARASITIC FUNGI AND MOULDS. 19 
 
 In 1869, De Taste ascertained that in the parish of 
 Chambray, after the peasants had uprooted all the 
 barberries which grew in the hedges, the harvest, 
 which had been bad in the foregoing year, was 
 gathered in under normal conditions for three suc- 
 cessive years. After the Lyons Railway Company had 
 planted a barberry hedge to fence the railway in the 
 parish of Genlis (Cote-d'Or), the cornfields bordering 
 on the line were attacked by rust in an aggravated 
 form. An inquiry made by the company showed 
 that the disease was due to the barberry, and that 
 where that plant was not found, the wheat was not 
 affected by rust. On the other hand, a single shrub 
 of barberry caused the disease to appear in a field 
 in which it had never occurred before. 
 
 The smut of wheat may be destroyed by the 
 application of quicklime, either dry or dissolved in 
 water, which destroys the fungus or checks its develop- 
 ment. Seed corn should always be subjected to this 
 operation when affected by smut. In default of quick- 
 lime, sulphate of copper is sometimes used, which 
 may be injurious, or sulphate of soda, dissolved in 
 water (eight kilograms to the hectolitre). This should 
 be done the day before the seed is sown. In the case 
 of corn intended for food, another process called pelle- 
 tage must be employed; this consists in the frequent 
 stirring of the granaried corn, either with the hand 
 or with Vallery's movable granary floor, so as to dry 
 and aerate it, and expel the dust and damp, which ai e 
 favourable to the development of fungi. 
 
 TOM 
 
'20 MICROBES, FERMENTS, AND MOULDS. 
 
 III. ASCOMYCETES ; ERGOT OF RYE ; THE MOULD OF 
 LEATHER AND DRIED FRUITS. 
 
 In distinction from the species just described, the 
 fungi in this group possess endogenous spores, enclosed 
 in a sac or special envelope which is called an ascus ; 
 hence the name of the family. Truffles, or Tuberacece, 
 are only reproduced by the spores contained in these 
 asci; but most of the other ascomycetes present in 
 addition several forms of spores, and the phenomenon 
 of alternation of generations has led to the belief that 
 in this case, as in that of the foregoing group, many of 
 the so-called species are only successive transformations 
 of one and the same species. This is the case with 
 the ergot of rye, a product used in medicine; it is, 
 however, a serious and dangerous disease of several 
 of our cereals, and particularly of rye (Fig. 8). 
 
 Ergot is caused by a minute parasitic fungus which 
 attacks the ear of rye when it is in flower. The 
 young flower is covered with a white mass, consisting 
 of microscopic spores, formerly termed sphacelium 
 (Fig. 9). These spores reproduce themselves on other 
 flowers, and propagate the evil. 
 
 The mycelium formed by the germination of the 
 sphacelium affects the grain, forms in it a thick felt- 
 work, and is developed so as to constitute the elongated 
 substance termed sclerotis (on account of its hardness), 
 or ergot ; it is called at this stage Claviceps purpurea. 
 
PARASITIC FUNGI AND MOULDS. 21 
 
 The sphacelium surrounding it falls off, and until the 
 
 Fig. 9. Sphacelium or 
 Claviceps purpurea, 
 the first stage ol'ergot 
 (magnified). 
 
 Fig. 8. Ear of rye, on 
 which there are several 
 grains of ergot. 
 
 Fig 10. Ergot hearing the organs 
 of fructification (magnified). 
 
 following spring the ergot remains stationary on the 
 soil on which it has fallen. 
 
22 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 In the spring, owing to the heat and moisture, the 
 hyphre of the sclerotis swell and send forth numerous 
 branches, bearing at their ex- 
 tremity a sort of rounded head, 
 in which the asci or peritheces 
 are developed (Figs. 10, 11, 12) ; 
 the endogenous spores issuing 
 from these asci germinate on 
 the rye-blossom, and produce 
 there a fresh sphacelium, then 
 a second ergot, thus always 
 passing through the same cycle 
 of alternation of generations. 
 Most of the Graminacece and several Cyperacece are 
 capable of producing ergots resembling those of rye, 
 
 Fig. ll. One of the heads or 
 organs ot fructification in 
 ergot, still more magnified, 
 a, peritheces. 
 
 Fig. 12. Portion of preceding figure tinder a very high magnifying power, showing 
 at b the asci, and at c the spores issuing from the asci or peritheces. 
 
 and possessing the same medical properties. The sug- 
 gestion has been made that instead of the ergot of rye 
 
PARASITIC FUNGI AND MOULDS, 23 
 
 the ergot of wheat should be used in medicine ; it is 
 larger, harder, and more elongated in form, and it also 
 appears to be less perishable. 
 
 Ergot of rye, especially when powdered, strongly 
 resembles meat in smell, and only becomes unpleasant 
 when the powder is spoiled by being kept in a damp 
 place ; it then smells like rotten fish, and this is the 
 case with many other fungi. 
 
 At first the taste is not very apparent, but it after- 
 wards produces on the pharynx a somewhat persistent 
 sense of constriction. The chief action of this drug 
 consists in producing contraction of unstriated muscu- 
 lar fibres, especially those of the uterus. Ergotine 
 and ergotinine are extracted from it, and these, which 
 are its active principles, are often employed in thera- 
 peutics in preference to raw ergot. 
 
 In large doses ergot is a strong poison. It then 
 produces characteristic symptoms, dilatation of the 
 pupils, retardation of the circulation, vertigo, stupor, 
 and even death. 
 
 Bread made with flour from which the ergot has 
 not been extracted may produce the grave symptoms 
 known as ergotism, and these soon become fatal unless 
 the use of such bread is discontinued. Sometimes 
 nervous symptoms predominate, and this is termed 
 convulsive ergotism ; sometimes the disease takes the 
 form of gangrene of the extremities, or gangrenous 
 ergotism, but these two forms are only two phases of 
 one and the same disease, and often occur in the same 
 
24 MICROBES, FERMENTS, AND MOULDS. 
 
 individual. In countries where rye bread constitutes 
 the chief food of the rural populations, as in Brabant, 
 the north of France, Orleannais and Le Blaisois, fatal 
 epidemics have been recorded at different times in the 
 Middle Ages, under the name of St. Anthony's fire. 
 The first symptoms are a species of intoxication, sought 
 after by the peasants, and becoming habitual, like 
 alcoholic drunkenness, up to the moment when con- 
 vulsions and gangrene set in, and death soon follows. 
 
 Ergot of maize produces analogous phenomena. In 
 countries where maize bread and cakes are in use, 
 as in Italy and South America, it appears to be the 
 cause of the disease improperly called Pelade. Of this 
 the shedding of the hair and skin is the first symptom.* 
 Fowls which feed on ergotized maize lay eggs which are 
 devoid of shell, owing to their premature expulsion 
 from the uterus ; their combs become black, shrivel, 
 and finally drop off; and they even shed their beaks. 
 All these phenomena may be easily explained by the 
 action of ergot on the muscular fibres of the uterus, 
 and of the blood-vessels. 
 
 Recent research has shown that Pelade is identical 
 in its cause and external symptoms w T ith the disease 
 known in northern Italy and in the south of France as 
 pellagra, and in Spain as the rose sickness. The latter 
 
 * We sli all presently see that the name Pelade was formerly given 
 to another parasitic affection, peculiar to that part of the skin covered 
 with hair. These two diseases must not be confounded, notwithstand- 
 ing the similarity of name, since they are produced by two fungi 
 belonging to different groups. 
 
PAKASITIC FUNGI AND MOULDS. 25 
 
 name is due to the red stains which cover the skin, 
 afterwards drying up and falling off in the form of 
 scales. At first the general health is not affected, and 
 several years may intervene before the occurrence of 
 vertigo, a want of appetite, emaciation, and finally the 
 torpor and convulsions which precede death. These ill 
 effects may be prevented by baking the maize before 
 grinding it, according to the process in use in Burgundy. 
 
 There is another very common fungus also belong- 
 ing to the group of ascomycetes, termed Eurotium 
 repens. This mould appears upon leather which has 
 been left in a damp place, and on vegetable or animal 
 substances in process of decomposition or badly pre- 
 served, and especially upon cooked fruits. 
 
 This mould is of a sombre green, a colour by no 
 means due to the presence of chlorophyl. On the 
 mycelium, which spreads over the substance of the 
 leather or of the fruit-skin, small stems are developed, 
 consisting of a jointed tube, and terminating in an 
 enlarged head on which chaplets of small grains are 
 formed, each of which is a spore. This was formerly 
 termed Aspergillus glaucus, and was regarded as a 
 peculiar species (Fig. 13). 
 
 When, however, this mould is developed in a place 
 in which the supply of air is limited, small gold-coloured 
 balls may often be observed beside or in the midst of the 
 stems, and these are filled with asci, each containing 
 eight spores. This second iform has been termed Euro- 
 tium repens. It has recently been ascertained that 
 
26 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 the balls in question are produced from the same 
 mycelium as Aspergillus glaucus, and that conse- 
 quently the chaplet of stalks and the balls filled with 
 asci are merely two organs of the same fungus. 
 
 Fig. 13. -Aspergillus glaucus, mould on leather and rotten fruits : a, hypha bearing 
 the chaplet of spores b, c, a germinating spore; d, ball of Eurotium; e, ascus 
 enclosing the endogenous spores (magnified). 
 
 The chaplet of spores in Aspergillus glaucus repre- 
 sent the white exogenous spores, or the sphacelium of 
 the ergot of rye, and those which are subsequently 
 
PARASITIC FUNGI AND MOULDS. 27 
 
 produced in the yellow balls correspond with those 
 which issue from the asci developed on the sclerotis ; 
 these are endogenous spores. 
 
 Many of the parasitic fungi belonging to the genera 
 Erysiphe, Sph&rict, Sordaria, Penicillium, etc., pre- 
 sent a similar mode of vegetation, and affect a large 
 number of plants. Such is the OiWium of the vine 
 (Erysiphe Tuckeri) to which we shall presently revert. 
 
 IV. OOMYCETES, MUCORINE^E, OR MOULDS, PROPERLY 
 
 so CALLED; PERONOSPORE.E ; THE POTATO-FUNGUS. 
 
 In all the parasitic fungi of which we have hitherto 
 spoken there is no sexual reproduction analogous to 
 that of the higher plants ; there are no male and female 
 organs comparable to the stamens and pistil. This 
 sexual reproduction exists in the oomycetes, although 
 only in a very elementary form. In 
 addition to the ordinary spores which 
 we have noticed in other fungi, there 
 are others termed oospores, which are 
 formed by the fusion of the originally 
 distinct contents of two different 
 cells. In the family of the mucorinese, 
 which includes most of the fungi Fjg u _ Mucor <ani . 
 commonly called moulds (Fig. 14), ^S^SSSt^g- 
 the two cells of which the contents 
 are fused together are similar. In the peronosporeae, 
 however, which includes the potato-fungus, one of the 
 
28 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 cells is larger than the other, and persists alone up to 
 the moment when the oospore is mature. It must, 
 therefore, be regarded as the female cell; while the 
 
 Fig. 15. Reproductive organs of Mucor mucedo (much magnified). 
 
 other, which is smaller and soon withers away, is the 
 male cell. 
 
 The mycelium of the oomycetes is developed in a 
 more or less liquid medium, like all other decomposing 
 and putrefying substances. The ordinary spores are 
 
PARASITIC FUNGI AND MOULDS. 
 
 29 
 
 very small, and are formed within a small enlargement 
 (sporangium) borne on a free hypha of the mycelium. 
 Their succession is constant and numerous as long as 
 the plant is in a favourable medium in which it can 
 flourish. The spores which are found in the same 
 medium germinate, and reproduce a mycelium similar 
 to that from which they had their origin. 
 
 Fig 16. Reproductive organs of Peronospora cdlotheca (much magnified). 
 
 The oospores may be as much as a thousand times 
 larger in volume than ordinary spores. They are only 
 formed when the growth of the fungus is on the wane, 
 as, for instance, when the substance serving as a sup- 
 port to the mycelium is drying off: a long period may 
 elapse before they germinate (Figs. 15 and 
 
30 MICROBES, FERMENTS, AND MOULDS. 
 
 Fig. 15 represents the reproductive organs of 
 Miicor mucedo. 1 is the sporangium filled with 
 ordinary spores; in 2, the wall of the sporangium 
 has disappeared, so as to show the free spores round 
 the central columella ; 3 and 4 represent the germina- 
 tion of these spores, giving forth their hyphae ; 5 gives 
 the conjugation of the sexual spores, which are fused 
 into one large oospore, 6 ; of this we see the germina- 
 tion in 7, and it produces a hypha terminating in a 
 sporangium. 
 
 Fig. 16 represents the same organs in a Perono- 
 spora. In 1 we see the mycelium of the fungus 
 penetrating the tissue of the infected plant; in 2, 
 the fructifying apparatus containing the ordinary 
 spores issues through a stoma, ramifies, and produces 
 sporangia at the extremity of each branch ; in 3 and 
 4 we see two spores which have issued from these 
 sporangia germinating and penetrating the epidermis 
 of a leaf through the stomata (a, 6) ; in 5 we see 
 the conjugation which has taken place between two 
 dissimilar cells : the male cell, smaller in size 
 (antheridium) is applied to the large female cells 
 (oogonium), and after this mode of fertilization it 
 is termed an oospore, which is represented in 6. 
 
 Mucor mucedo, and other species of the same 
 genus, form the small downy tufts of a greyish white 
 colour which may be observed on mouldy bread, rotten 
 fruits, and on the excrement of horses, dogs, and 
 rabbits. When examined under the microscope, the 
 
PARASITIC FUNGI AND MOULDS. 31 
 
 filaments of which these tufts consist display at their 
 extremities the sporangia represented in Fig. 15, 1. 
 On rotten fruits, the spores of these fungi germinate 
 in five or six hours by introducing their hyphse 
 through the epidermis. Sleepiness, which is only the 
 first stage of rottenness, is, according to Davaine, 
 to be ascribed to the action of these fungi. Fruit in 
 this mouldy condition is sometimes unwholesome. 
 
 The potato-fungus, Peronospora infestans, is one 
 of the most dreaded scourges of this valuable plant. 
 It attacks the lower surface of the leaves and stalks, 
 and appears in the month of July, in the form of 
 brown patches. The long hyphse penetrate deeply 
 beneath the epidermis, and will even propagate them- 
 selves on the tubers. 
 
 Among the causes which produce or promote this 
 disease, agriculturists place the excessive moisture 
 of the soil, setting the plants too late in the season, 
 the use of bad seed, the premature and exhausting 
 germination of the tubers before they are planted, 
 and the use of fresh dung which is not sufficiently 
 decomposed. 
 
 The following process is indicated as likely to 
 prevent the development of this parasite. In the 
 spring, the first protective ridge should be prepared 
 with a flat top, from eight to ten centimetres high, 
 and from twenty-five to thirty centimetres wide. 
 In the first fortnight of August, a second protective 
 ridge should be earthed up, of which the edge should 
 
32 MICROBES, FERMENTS, AND MOULDS. 
 
 be acutely sloped, and the stalks of the plant should 
 be turned down into the furrow, so that any spores 
 which may be on the leaves may be washed off them 
 by the rain, and not come into contact with the stem 
 and roots of the plant. 
 
 It is probable that earth-worms diffuse the spores 
 of this fungus, as well of those of many other 
 microbes. 
 
 According to Prillieux, beetroot is attacked by 
 another species of Peronospora, which causes the 
 leaves of the plant to wither and fall. The remedy 
 consists in burning the dead leaves on which the 
 oospores remain during the winter, or, at any rate, 
 in not allowing them to be placed on the dung-heap. 
 
 The mildew which affects the vine is also a species 
 of Peronospora (P. viticola) as we are about to show. 
 
 "V". PARASITIC FUNGI OF THE VINE: OIDIUM, 
 MILDEW, ETC. 
 
 The parasites of the vine are so numerous as to 
 require a separate chapter. Some years ago, in 1870, 
 fifty of them were enumerated b}^ Roumeguere, a well- 
 known specialist, and the number is now more than 
 doubled. We shall only now speak of the more 
 important, of those which are especially injurious 
 to the vine, and which consequently are the most 
 interesting to us. 
 
 j 
 
PARASITIC FUNGI AND MOULDS. 33 
 
 Oidium. Oidium, or Erysiphe Tuckeri so 
 called from the name of the vine-grower by whom 
 it was first described has been longest known to 
 us among these parasitic fungi. It belongs to the 
 group of Ascomycetes, and appears to have reached 
 us from America in 1845, in which year it was first 
 observed in England. Thence it passed over to 
 France. In 1847 it was noticed in the neighbourhood 
 of Paris; and afterwards, in 1850-1851, in the south 
 of France, where for twenty-five or thirty years it 
 raged with such intensity as to threaten for some 
 years the almost complete destruction of the vine- 
 yards, a destruction which is now taking place under 
 the attacks of another parasite, belonging in this 
 instance to the animal kingdom: Phylloxera vastatrix. 
 
 The oidium, the white disease or meunier, was 
 equally destructive in the vineyards of Madeira, so 
 that it was necessary to uproot all the vines, and 
 replace them by sound plants which were incapable 
 of bearing grapes for some years. 
 
 The oidium appears on the grape in the form 
 of greyish filaments, terminating in an enlarged head, 
 which contains an agglomeration of spores, not free 
 or in a chaplet, as in Aspergillus (Fig. 13). These 
 spores escape as fine dust, diffuse themselves in the 
 air, and spread the disease afar with extreme facility. 
 
 If a spore lodges on a vine-leaf under favourable 
 conditions of moisture and warmth, it soon germinates, 
 penetrates the epidermis by means of its hyphse, and 
 
34 MICROBES, FERMENTS, AND MOULDS. 
 
 forms floury patches which send forth a peculiar 
 musty smell. 
 
 The oidium may remain latent on the vine-stock 
 throughout the winter. In the spring it reappears 
 in yellowish patches on the earliest leaves, on which 
 it is rapidly propagated ; the plant languishes, and 
 the leaves become pale and, as it were, anaemic. 
 
 Very dry weather is unfavourable to oidium, and 
 so also are heavy rains, which wash the fruit and 
 leaves, and carry away the spores on to the soil. 
 
 The remedy consists in the application of sulphur 
 to the infected vines. Flowers of sulphur is used, 
 which acts upon the fungus by gradually setting free 
 sulphurous acid. Under this influence the microscope 
 shows that the superficial mycelium and the fragile 
 spores dry up as if they were burnt (Ed. Andre 7 ). 
 Three successive applications are necessary, and these 
 are made with the help of a special instrument in 
 the form of a pair of bellows, to which a rose is 
 affixed, in order to disseminate the flowers of sulphur. 
 The first application is made in spring, when the 
 shoots are from eight to ten centimetres long; the 
 second directly after the vine has blossomed; and 
 the third when the grapes begin to ripen. The opera- 
 tion in spring is the most important, and should be 
 performed with the utmost care, so as to affect all 
 the hybernating spores from which the succeeding 
 generations would issue. Not only the uppei and 
 lower sides of the leaves must be dusted, but also 
 
PARASITIC FUNGI AND MOULDS. 35 
 
 the branches and the stock itself. The third applica- 
 tion should be made early enough for the sulphur to 
 have disappeared from the grapes before the vintage 
 takes place, It is evident that its introduction into 
 the wine would have the worst effect : in process of 
 fermentation sulphuretted hydrogen would be given 
 off, which is injurious to the alcohol, and this gas 
 would give an unpleasant taste to the wine. 
 
 The morning is the best time for applying the 
 sulphur, since the dew enables the powder to stick 
 to the leaves and branches ; and it should be made 
 on a fine day, since heavy rain would carry off' the 
 sulphur before it has time to act upon the oidium. 
 
 The sulphur which ultimately reaches the soil 
 below the vine is transformed into sulphate of lime, 
 which is an excellent dressing for the vine. 
 
 Mildew. This new parasite, of which the scientific 
 name is Peronospora viticola, belongs to the group 
 of Oomycetes. It also comes to us from America. 
 It was imported into Europe in 1878, with the 
 American plants destined to replace those destroyed 
 by the phylloxera, and was rapidly diffused through 
 France, and thence to Algeria. It appears in the 
 form of irregular patches of a whitish colour, not 
 very thick, and with an almost crystalline appear- 
 ance like that of a saline efflorescence (Planchon). 
 It has not the mouldy smell of oidium, and appears 
 later in the season, generally on the autumn shoots. 
 Its mycelium penetrates more deeply than that of 
 
36 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 o'idium. Brown patches appear on the upper surface 
 of the leaf, as if it had been scorched ; and in corre- 
 spondence with these there is a delicate down " like 
 the whiteness of a slight hoar-frost " (Vaissier) on its 
 lower surface. The hyphae issuing from the mycelium 
 ramify at right angles, and these branches bear the 
 spores, as in the potato- fungus, Peronospora infestans 
 (Figs. 17, 18). These numerous spores, diffused through 
 the air, are powerful sources of contagion. 
 
 Fig. 17. Mildew : a, veitical section of a leaf, bearing tufts of Peronospo a viticola 
 on its lower surface; b, a withered leaf, bearing the winter spores (oospoies} 
 (x 20diaui.). 
 
 This parasite destroys the tissue of the leaf, 
 exhausts it, and finally causes it to wither and fall. 
 Those which are least affected have only diseased 
 patches. The bunch of grapes and the young 
 herbaceous shoots are rarely affected. 
 
 In addition to the ordinary or summer spores of 
 which we have spoken, the sexual spores must be 
 noted ; the oospores, or dormant winter spores, which 
 
PARASITIC FUNGI AND MOULDS. 
 
 37 
 
 hybernate in the tissue of the leaf itself (Fig. 17, l\ 
 
 and germinate in the spring. The conjugation of the 
 
 sexual spores, as well as the ripening of the summer 
 
 spores, and the germination 
 
 of the zoospores which issue 
 
 from them, can only occur in 
 
 a drop of water, rain, dew, 
 
 or mist, so that a persistent 
 
 drought checks the propagation 
 
 of this fungus. 
 
 The parasite injures the 
 stock by stripping it of its 
 leaves, thus hindering the nu- 
 trition of the plant ; moreover, 
 the grapes, since they are im- 
 perfectly protected from the 
 sun, dry up before they are 
 ripe. Sometimes, also, the 
 fungus attacks the grape itself, 
 or its peduncle. 
 
 Vines planted in a moist soil resist its attacks 
 better than others, simply because the nature of the 
 soil makes the plant more vigorous, and suitable 
 manure acts in the same way. When the fungus is 
 developed, it may be destroyed by sulphur mixed 
 with powdered lime. Since its mycelium is more 
 deeply seated than that of oidium, it is necessary 
 to have recourse to more vigorous measures in order 
 to reach it. Powdered borax has also been pre- 
 
 Fig. 18. Group of tnfts of Pero- 
 nospora infestans, issuing MODI 
 a stoma on the lower surface of 
 the leaf and bearing the summer 
 spores (x 120 diaui.)- 
 
38 M1CKOBES, FERMENTS, AND MOULDS. 
 
 scribed, in the proportion of fwe grammes to a litre 
 of water ; also a solution of sulphate of iron, one 
 kilogram to two litres of water, with which the 
 stock should be washed fifteen days before the shoots 
 begin to start (Millardet). Mme. Ponsot, in Bordelais, 
 has used the same substance mixed with lime (four 
 parts of powdered sulphate of iron to twenty parts 
 of lime). The fallen leaves which contain the 
 winter spores, or oospores, should be burnt or buried. 
 The stocks should be irrigated as often as possible, 
 and the leaves should be dusted with lime in order 
 to dry off the dew or mist, which favours the fertili- 
 zation of the oospores. 
 
 Some species of vines resist the disease better 
 than others, and this is the case with the Labernet, 
 a vine from Medoc, which has remained almost 
 entirely free from it in infected regions of Algeria. 
 
 Anthracnosis, or Black-rot. This fungus, of which 
 the name is Phoma uvicola, or Sphaceloma ampelium, 
 belongs to the ascomycetes. Of all the parasites of 
 the vine it was the earliest known, but it was only 
 in 1878 that its devastations were important enough 
 to attract attention. Like the two preceding fungi, 
 it is reproduced by spores carried afar by the slightest 
 breeze. Heat and moisture are favourable to its pro- 
 pagation, which is checked by drought. 
 
 It appears on the young shoots in the month 
 of May, in the form of round black spots which 
 gradually spread over the twigs, leaves, and grapes 
 
PAKASITIC FUNGI AND MOULDS. <J9 
 
 The young stalks assume a sickly appearance, and 
 often wither off, together with the leaves and fruit. 
 
 When the fungus fastens on the fibro-vascular 
 bundles of the leaves before their complete develop- 
 ment, the leaves shrivel and curl up, and perform their 
 functions imperfectly ; when it attacks the petiole or 
 peduncle of the bunch of grapes, it dries up, and the 
 destruction of all the parts in dependence on it soon 
 follow. It is this fungus which, under the name of 
 rot, now devastates the American vineyards. 
 
 Sulphur is by no means so efficacious in this case 
 as it is with oidium, but the following treatment is 
 prescribed by Fortes : 
 
 1. The prunings of the vine and other remains 
 of the preceding years should be destroyed 2. The 
 suckers and young shoots should be dusted, in the 
 second fortnight of April, with slaked lime which has 
 been finely powdered, and this operation should be 
 repeated once a fortnight up to the end of June. 
 3. Sulphur should be applied at the usual times, 
 especially if there is any oidium. 4. The vines 
 should be drained and irrigated as often as possible. 
 5. In all cases in which the fungus can be detected, 
 powdered lime should be applied at the interval of 
 some days, alternately with the same substance mixed 
 with flowers of sulphur. 
 
 Aubernage, called by the Italians the Black disease, 
 must not be confounded with Anthracnosis. Accord- 
 ing to recent researches, aubernage is not produced 
 
40 MICROBES, FERMENTS, AND MOULDS. 
 
 by a fungus, but by a degeneration which is either 
 spontaneous or, as Pirotta and Cugini suggest, the 
 work of bacteria, and which consists in the trans- 
 formation of the cellulose and starch of the plant 
 into dextrine, as Comes asserts, or, according to Pirotta, 
 into tannin. 
 
 This disease appears in three stages : (1) a simple 
 discolouration of the sap, which assumes a tawny 
 black shade without checking vegetation ; (2) a begin- 
 ning of necrosis, which renders the plant unhealthy ; 
 (3) a complete necrosis, which affects the woody parts 
 and arrests the growth of the plant. 
 
 This disease is contagious, which leads us to 
 believe that if it is not produced by a fungus, it is 
 at any rate due to the development of a bacterium 
 that is, of a microbe. 
 
 The remedy indicated by Italian naturalists con- 
 sists in the application of salts of potassium, which 
 may be extracted at small cost from the ashes of the 
 vine branches which are burnt upon the spot. 
 
 Rcesleria hypocjea, or Rot. This parasitic fungus is 
 found on the vine-roots, and has been recently studied 
 by Prillieux. The vine affected by this parasite 
 languishes for some years and then dies. The evil 
 spreads by means of the roots to adjoining stocks, 
 and the parts affected spread like the patches formed 
 by the phylloxera. The roots rot away. This disease 
 has been widely spread in Haute Marne. 
 
 This small fungus is distinct from one which bears 
 
PARASITIC FUN.. 41 
 
 the same French name, Pourridie, which is found 
 in the south of France, and has been studied by 
 Planchon and Millardet. These naturalists describe 
 it as formed by the rhizomorphous mycelium of 
 a large hymenomycetous fungus, Agaricus melleus. 
 Rcesleria is very different. It is a small white fun- 
 gus, with a white or ash-coloured head, from eight 
 to ten millimetres in size, of which the mycelium 
 lives in the interior of the vine-roots, penetrating 
 and profoundly affecting all the tissues of the roots, 
 and producing in the autumn the fructification which 
 comes to the surface. 
 
 It is generally developed in marly and argillaceous 
 soils, after a rainy season, and in the low-lying parts 
 of vineyards on the slope of a hill. It thrives in 
 the moisture which lies below the surface of the soil, 
 and it is therefore important to improve the con- 
 dition of those sub-soils which are impermeable. 
 
 It is also necessary to separate the stocks, so as 
 to prevent their roots from interlacing, and to uproot 
 and burn diseased vines, since the fungus may subsist 
 for several years in dead and dried roots. If, which 
 is almost always the case, any fragments of roots 
 remain in the ground, they will reinfect the sound 
 stocks which have been substituted for them. 
 
 Remarks on Diseases of the Vine. We may be 
 surprised that this valuable plant, which has been 
 so carefully cultivated in France, should be attacked 
 by such a number of parasites, both animal and 
 
42 MICROBES, FERMENTS, AND MOULDS. 
 
 vegetable. Yet we should rather be surprised that 
 the vine has not been completely destroyed by the 
 combination of such diverse scourges, and that it has 
 effectually resisted them in several regions of France. 
 When we consider that for long years the same hoary 
 old stocks have been required to produce grapes 
 without truce or mercy, and often without taking 
 pains to supply to them by a fitting manure the 
 nourishment which is withdrawn from them by the 
 fructification of the grape, we shall be less astonished 
 at the decadence of our vineyards. And, indeed, 
 enlightened minds ascribe the attacks of these 
 numerous parasites to the weakness and exhaustion 
 of our vines, rather than to any accidental cause, such 
 as an importation from without. 
 
 The principal remedy may, therefore, be found in 
 restoring the strength of the vine by the planting of 
 young suckers, and still more of seedlings. Instead 
 of attempting to introduce foreign plants, which it 
 may not be easy to acclimatize, and which will 
 certainly be less valuable than the vines we have 
 lost, it would surely be better .to seek to regenerate 
 our indigenous kinds by crossing the cultivated stocks 
 with wild vines, or else, as Millardet suggests, by 
 crossing them with each other. The attempt might 
 also be made to graft the stocks from Bordeaux and 
 Burgundy on wild or American vines, which offei 
 a better resistance to the attacks of the phylloxera. 
 
PARASITIC FUNGI AND MOULDS. 43 
 
 VI. HABITAT OF PARASITIC FUNGI: THEIR DESTRUC- 
 TIVE ACTION. 
 
 The habitat of parasitic fungi is extremely varied. 
 Roumeguere, in his Cryptogamie illwstree, has devoted 
 more than forty pages of a large quarto, printed in 
 three columns, merely to the enumeration of fungi, 
 classified according to their position in plants, animals, 
 organic or inorganic substances, and the author himself 
 admits that this list is far from complete. 
 
 Parasitic fungi are found on plants belonging to 
 all the families of the vegetable kingdom, and also 
 on other fungi ; on living animals, vertebrate and 
 invertebrate ; on their dead bodies and on excrement ; 
 in stagnant waters and in the sea, on piles and rocks. 
 Others prefer marshes, turf-bogs, heathy ground (which 
 may be marshy or dry), dunes, caves and holes, and 
 even completely covered by the soil, as is the case 
 with truffles. Others, again, grow upon stones, walls, 
 and rocks ; in the open air or in ruins ; or, like Torula 
 conglutinata and Himantia cellaria, in the darkest 
 caves, where they form a species of feltwork, often 
 several centimetres in thickness, of a blackish colour, 
 ragged, and extremely light, which in the course of 
 a few years overspreads the walls of cellars. Other 
 fungi inhabit our houses, attack our food, clothes, 
 utensils of every kind; wall-papers and books, of 
 which the paste offers a nutriment which they can 
 
44 MICROBES, FERMENTS, AND MOULDS. 
 
 \ 
 
 easily assimilate ; linen ; and even our toilet sponges, 
 notwithstanding that they are in daily use. They 
 may even be found on the most powerful chemical 
 substances, on pastilles of sulphur, arsenical solu- 
 tions, etc. 
 
 " The general belief," writes Roumeguere, "regards 
 fungi as the result of decomposition. This belief is 
 due to an imperfect acquaintance with the nature of 
 these plants. Fungi are not only found on fragments 
 of wood and decayed vegetables, but sometimes even 
 on bare pebbles, on glass, on window-panes, on the 
 lenses of microscopes, and on other polished surfaces. 
 It must be supposed that fungi are able to extract 
 the elements of nutrition even in such positions. 
 Coprins, which have a surprising power of develop- 
 ment, grow on amputated limbs. Young has recorded 
 the appearance of a great number of these fungi, still 
 in an imperfectly developed state, below the mattress 
 on which a man was lying whose leg had been ampu- 
 tated. The bed was cleaned, and in nine or ten days 
 the fungus reappeared in the same abundance as 
 before. Targionni-Tozetti had previously observed a 
 similar growth on the apparatus which surrounded a 
 fractured limb in St. George's Hospital, Modena." 
 
 Berkeley states that immediately after the death 
 of any vegetable substance, an army of fungi of 
 various kinds is at hand to complete the work of 
 decomposition. The soft tissues are rapidly reduced 
 to a semi-fluid condition by the combined action of 
 
PARASITIC FUNGI AND MOULDS. 45 
 
 putrefaction and of these fungi. The hardest wood 
 yields to the same agents, not indeed so quickly, yet 
 much more rapidly than would be the case from the 
 action of the constituents of the atmosphere alone. 
 When a log of one of our finest trees is attacked by 
 fungi, it soon becomes only a mass of rotten wood, 
 of which the woody tissue has been traversed and 
 destroyed by the mycelium. If the same log were 
 merely subjected to the action of the weather, it 
 might endure for half a century before becoming 
 completely rotten. 
 
 Merulius destruens (or M. lacrymans) attacks 
 beams and the other pieces of wood used in building, 
 and rapidly destroys them. The administrators of the 
 Canal du Midi, Toulouse, were compelled to replace 
 the oak piles which protect the sides of the canal as 
 it traverses the town, on account of the ravages of 
 Dematium giganteum, one of the higher orders of 
 fungi in its early form. At the end of the last 
 century, the same fungus destroyed, in the course of 
 two or three years, the Foudroyant, a sixty-gun 
 vessel. 
 
 In order to stop the development of these fungi in 
 wood used for building, and especially in wood in- 
 tended for ship- building, it is expedient, as soon as 
 the trees are felled, to steep them in a metallic 
 antiseptic solution as, for instance, in sulphate of 
 copper. 
 
 An experiment made by Nageli, a celebrated 
 
46 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 botanist in Munich, demonstrates the action of micro- 
 scopic fungi on organic substances, exclusive of any 
 previous deterioration. 
 
 "I enclosed," he says, "several loaves in a tin case, 
 which was carefully but not hermetically closed. 
 When the case was opened at the end of eighteen 
 months, the loaves were reduced to a small mass, 
 consisting almost entirely of filaments of mould, in 
 which I could detect no trace of the substance of 
 bread. This mass was soft and moist, like a mud-pie. 
 It emitted a strong odour of trimethylamin : no trace 
 of starch remained. One hundred parts in weight 
 of the original bread were transformed into sixty-four 
 parts in their moist state, and seventeen parts after 
 desiccation in the open air. The 
 starch had been consumed in order 
 to form carbonic acid and water." 
 
 Badham sums up in a few 
 words the destructive effects of 
 microscopic fungi. " Mucor mu- 
 cedo," he writes, " devours our pre- 
 serves; Ascophora mucedo turns 
 our bread mouldy; Molinia is 
 nourished at the expense of our 
 fruits; Mucor herbarium destroys 
 the herbaria of botanists; and 
 Chcetonium chartatum (Actino- 
 spora) develops itself on paper, on the insides of books, 
 and on their binding, when they come in contact with 
 
 Fig 19. CliniHitium char- 
 tatum, mould ou paper. 
 
PARASITIC FUNGI AND MOULDS. 47 
 
 a damp wall (Fig. 19). When beer or sweetmeats turn 
 sour, it is the work of a fungus." 
 
 VII. PARASITIC FUNGI OF INSECTS, REGARDED AS 
 ALLIES OF MAN. 
 
 Many microscopic fungi attack insects, both living 
 and dead. We have all seen the bodies 
 of flies still sticking to the window- 
 pane or curtain, and surrounded by a 
 species of aureole formed by the growth 
 of a fungus, Penicillium racemosum, flyftur 
 
 7 an aureole of Sapro- 
 
 or sometimes Sporewdonema muscce or 
 
 Saproleynia ferax, of the family of Oospores (Figs. 
 20, 21, 22). 
 
 Cordiceps attacks certain caterpillars of the genera 
 Cossus and Hepialus, when they are buried in the 
 sand before their metamorphosis into chrysalides, and 
 kills them by the development of its mycelium in 
 their tissue. These caterpillars may often be found, 
 bearing on their backs a fungus longer than them- 
 selves (Fig. 23). 
 
 Sphceria militaris, a parasite to Bombyxpityocarpa, 
 the caterpillar found on pine-trees, represents one of 
 the few fungi which may be regarded as beneficial 
 to man, since it destroys multitudes of these cater- 
 pillars, and thus neutralizes the ravages caused by 
 their devouring the young shoots and pine needles. 
 
 In the Antilles there is a wasp called the vegetable 
 
48 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 wasp, because it is attacked during its lifetime by 
 a fungus which it carries about for some time, and 
 which finally causes its death : this is Torrubia 
 spherocephala (Tulasne). Isaria sphingum, another 
 
 Fig. 21. Two fi'aments of Sapro- 
 legnia containing spores (greatly 
 magnified). 
 
 Fig. 22. Oogonium of Saprolegnia 
 surrounded by Antberidia (much 
 magnified). 
 
 species of the same genus, has been observed on the 
 back of a butterfly, which was poised upon a leaf as 
 if alive, and which was probably killed by the 
 development of the fungus. 
 
 These and other facts, not to speak of the 
 muscardine of silkworms, to which we shall return, 
 
PARASITIC FUNGI AND MOULDS. 
 
 49 
 
 have given rise to a surmise that if we could discover 
 the parasitic fungus of the phylloxera, we might 
 transform it into a powerful auxiliary of agriculture, 
 since by its aid the parasitic insect which 
 now ravages our vineyards might be 
 destroyed. 
 
 From this point of view Giard 
 has observed several of these parasites 
 of insects, which he calls Entomo- 
 phthorece, from the name of their prin- 
 cipal genus, Entomophthora. Such is 
 E. rimosa, which attacks grasshop- 
 pers and the diptera of the genus 
 Chironomus, enveloping them in a thick 
 felt work formed by the winter spores, Fig. 23. Butterfly- 
 
 nymph bearing 
 
 and speedily killing them. In the 
 
 same manner Isaria pulveracea attacks Pyrrhocoris 
 apterus, an insect which is often injurious to our 
 kitchen gardens. 
 
 It has been asked whether Entomophthora Plan- 
 choni, the parasite of the aphis, might not also prey 
 upon the phylloxera, but the experiments made in 
 this direction have not hitherto been so successful as 
 to allow us to count on this means of averting the 
 scourge. With the same object, Hagen has suggested 
 the use of beer-yeast, which seems to have a destruc- 
 tive effect on insects, as it is developed in their tissues. 
 
50 MICROBES, FERMENTS, AND MOULDS. 
 
 VIII. MUSCARDINE, THE DISEASE OF SILKWORMS. 
 
 Muscardine, which is caused by a true fungus, 
 Botrytis bassiana, must not be confounded with other 
 diseases which attack the silkworm, such, for instance, 
 as pebrin, which, as Pasteur asserts, is caused by a 
 bacterium, or, strictly speaking, a microbe, and, accord- 
 ing to the recent researches of Balbiani, by Psoro- 
 spermia. We shall presently revert to this disease. 
 
 Botrytis bassiana is a true mould, belonging to 
 the group of Oomycetes, and allied to the potato- 
 fungus, Peronospora. It is propagated by spores, 
 which, when falling on a silkworm, germinate and 
 penetrate its body. A mycelium is then developed, 
 which may take possession of the whole caterpillar 
 without appearing externally. The germination is 
 rapid in proportion to the age of the silkworm. 
 
 When death has been caused by the develop- 
 ment of the mycelium, hyphae appear through the 
 animal's skin ; these soon bear white, chalky spores, 
 which are readily detached and float in the air in im- 
 palpable dust like smoke. The silkworms on which 
 the dust falls do not appear to be diseased, and eat 
 with avidity, but they die suddenly. It takes from 
 70 to 140 hours to develop the spores and spread 
 the contagion. It is difficult to free the breeding- 
 houses from all the silkworms which die in this 
 manner ; those which die after having crawled up 
 to the heather to prepare for their transformation 
 
PARASITIC FUNGI AND MOULDS. 51 
 
 into chrysalides are only thrown away when they are 
 found on removing the cocoons. The clouds of dust 
 dispersed by the silkworms perpetuate the disease 
 in the best-ordered factories. When the heather is 
 thrown out of window, and the rooms are swept to 
 get rid of the dust, the spores float in the air and 
 are dispersed by the wind. 
 
 Damp favours the development of the fungus, and 
 the introduction of healthy silkworms into an infected 
 breeding-house will not extirpate the disease. In order 
 to attain this object, it is necessary to get rid of all 
 the dead silkworms before the development of the 
 spores, and to destroy their bodies by burning them 
 with the heather, or with quicklime. The breeding- 
 houses should then be completely emptied, and the 
 compartments should be purified and disinfected in 
 the ordinary way by fumigation with sulphur, and 
 washed with chlorine water, before fresh silkworms are 
 placed in them. 
 
 IX. PARASITIC FUNGI OF THE SKIN AND Mucous 
 MEMBRANE OF MEN AND ANIMALS. 
 
 The skin -diseases of man and animals which are 
 termed tinea are caused by the presence of parasitic 
 fungi, just as the itch is produced by the presence 
 of animals belonging to the group Acarus. These 
 diseases are rendered eminently contagious by the 
 dissemination of the spores of these fungi, which will 
 
52 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 germinate wherever the conditions of heat and moisture 
 are favourable, even on a healthy skin, or where it is 
 only irritated by a simple scratch. 
 
 Ringworm, Achorion Schoenlenii, the fungus 
 which produces this disease on the parts of the 
 skin covered by hair, belongs to the same family as 
 oi'dium. Its mycelium produces hyphse, bearing 
 chaplets of spores, as in the Mucorineae, but there is 
 no true sporangium. 
 
 Fig. 24. Achonon Scho&nlenii, fungus of ringworm ( x 400 diam ) : a, spores ; &, chains 
 of spores ; c, mycelium. 
 
 They are found in abundance in spots of ringworm, 
 amidst the sulphur-coloured substance which carpets 
 them. If a morsel of this substance is dissolved in 
 ammonia, the fungus is detached, and may be observed 
 under the microscope, especially if care has been taken 
 to stain it brown by an aqueous solution of iodine 
 (Fig. 24). 
 
PARASITIC FUNGI AND MOULDS. 
 
 The mycelium consists of elongated, cylindr: 
 articulations, which find their way among the cell 
 the epidermis, especially in the vicinity of the ec 
 of the patch, and may penetrate deeply into the der 
 (Fig. 25). Some of the shorter filaments terminati 
 
 Fig. 25. Transverse section of skin, on the level of a spot of ringworm : a, epide 
 b. superficial layer of dermis; c, deep layer of the dermis; d d' mycelium 
 spores. 
 
 chaplets of spores, which are successively detac 
 from the stem ; they are therefore found detachec 
 large numbers in the midst of the epidermic c< 
 The centre of the patch is occupied by one or more i 
 
f)4 MICROBES, FERMENTS, AND MOULDS. 
 
 infected hairs, surrounded by spores; but, while the 
 centre is in process of healing, the fungus extends to 
 the periphery and continues to spread. The raised 
 surface of the patch is formed by this parasitic growth, 
 which forms a circular excrescence, always increasing 
 in size, while raising and thickening the epidermis. 
 The parts affected by the mycelium are characterized 
 by a slight suppuration throughout the patch ; the 
 indurated tissue is gradually absorbed, leaving deep 
 scars which persist after a cure has been effected. 
 
 The mycelium is found on infected hairs between 
 the coats of their bulbous roots, while the numerous 
 spores are only found between the epidermic layers of 
 the hair. 
 
 This fungus may be inoculated in all parts of the 
 skin, but its favourite site is the head, where it pro- 
 duces the disease long known as ringworm, or favus. 
 
 It has been already said that fungi prey upon each 
 other. Thus Achorion has for a parasite Puccinia favi, 
 a minute fungus of a reddish-brown colour, which is 
 often developed on the whitish epidermic scales which 
 cover the mycelium on fresh spots of ringworm. The 
 same parasite has also been observed on Pityriasis. 
 
 Trichophyton tonsurans. This fungus, allied to 
 the preceding, subsists likewise on skin covered with 
 hair, and produces tinea tonsurans. 
 
 It is formed of a mycelium with two sorts of 
 hyphse, some simply nutritive, others with short 
 articulations, separating into chaplets of rounded 
 
PARASITIC FUNGI AND MOULDS. 55 
 
 spores, which are continually detached (Fig. 26). The 
 
 Fig. 26. Trichnphyton tonsurans on the epidermic layers of a paich of circinn&te 
 herpes: a, spores; b, mycelium with long articulations; c, mycelium with short 
 articulations ( x 4UO diam.). 
 
 mycelium is often ramified, and penetrates within the 
 epidermic cells, especially at 
 the base of the hairs. 
 
 It is probably that the 
 parasitic Sycosis which affects 
 the beard, and circinnate 
 herpes, two other skin-diseases, 
 are only varieties of the same 
 disease. In fact, Cornil and 
 Ranvier have ascertained that if Trichophyton is in- 
 serted in the glabrous chin of a child, it will produce 
 
 Fig. 27. Spores and filaments of 
 Trichophyton, germinating on 
 two epidermic cells of the skin. 
 
56 MICROBES, FERMENTS, AND MOULDS. 
 
 herpes; and that parasitic herpes may also be pro- 
 duced on the back of the hand by the transference 
 of the fungus from a patch of Tinea tonsurans. 
 
 The fungus may be transmitted to cats, dogs, and 
 horses, who thus become agents of the contagion. A 
 fresh study of the disease has been recently made by 
 an Englishman, Dr. Thin, and he also regards it as 
 identical with herpes, or Tinea circinata. 
 
 According to this observer, the contagion is not 
 transmitted by floating spores, but only by direct 
 contact, and especially by the exchange of hats and 
 caps so common among school -children. 
 
 Experiments in artificial culture in milk, carrot- 
 juice, or aqueous humour show that the fungus cannot 
 be developed when the hair on which the spores are 
 is entirely submerged ; a certain degree of moisture is, 
 however, necessary, which is probably more frequentty 
 found on children's heads. In adults, the bulbous root 
 of the hair is dryer between the follicle and the skin. 
 The parasite may be destroyed by causing an inflam- 
 mation of the part affected, since the serous effusion 
 thus produced places the hair in the same conditions 
 as in the culture-liquids in which it is completely 
 covered, and not floating. 
 
 Pityriasis versicolor is produced by a fungus 
 resembling the foregoing, termed Microsporon furfur. 
 It grows between the cells of the epidermis, and 
 effects their rapid degeneration. The hyphae have 
 long articulations, intermixed with round spores, not 
 
PARASITIC FUNGI AND MOULDS. 
 
 57 
 
 arranged in a chaplet, but grouped below the 
 epidermis (Fig. 28). The development is very slow, 
 
 Fig. 28. Microsporonfurfur: a, b, groups of spores; c, mycelium with long, trans- 
 parent, and curved articulations. 
 
 but the fact of its inoculation can be established, and 
 artificial cultures may be made. 
 
 In the two parasites of which we have now to speak 
 
58 MICROBES, FERMENTS, AND MOULDS. 
 
 we cannot recognize any mycelium, and in this par- 
 ticular they are allied with the ferments, of which we 
 shall speak presently. The fungus consists of round 
 cells, which m ultiply by budding. De Lanessan 
 regards them as a separate group, to which he gives 
 the name of Microsporete, while he designates those 
 parasites of skin covered with hair which possess a 
 distinct mycelium under the name of Trichophyta. 
 The Pelade Fungus. Pelade is another disease of 
 
 c 
 Fig. 29. Pelade fungus : epidermic cells, charged with spores ( x 500 diam.). 
 
 the skin covered with hair, which is caused by Micro- 
 sporon Audouini, and which presents the characters 
 just indicated. It would, therefore, be an error to 
 give it the same generic name as Microsporon furfur, 
 a fungus of which the mycelium is well developed, 
 if the recent researches of Grawitz, to which we 
 shall presently return,* did not tend to snow that 
 Microsporeae and Trichophyta are only forms of the 
 same parasite in different phases. 
 
 * Sec chapter on Polymorphism of Microbes. 
 
PARASITIC FUNGI AND MOULDS. 
 
 59 
 
 The pelade fungus develops in the superficial 
 horny layer of the epidermis, on the surface of the 
 epidermic cells, and in their interstices. It does not 
 penetrate the hair-follicles, and is only occasionally 
 found on the hairs, in which case it is fastened to the 
 detached pellicles of the epidermis, not to the interior 
 
 JO 00 
 
 <U> 
 
 6 
 
 
 
 42 
 ftOdO O 
 
 40 3 
 
 ^r ^^ 
 
 tig. 31. Isolated spores, taken from 
 patches of pelade: 1, 2, 3, 4, large 
 spores ; 5, budding spores ; 6, 7. 8, 
 empty spores ; 9 to 12, small spores 
 (X 1000 diam.). 
 
 Fig. 30. Hair affected by the 
 rapid progress of Pelade 
 cU : calvante. It is surrounded 
 by epidermic cells charged 
 with spores (x 2U8 diam.). 
 
 of the hair (Figs. 29, 30). It is composed entirely of 
 the round spores already described, which are re- 
 produced by budding (Fig. 31). 
 
 The Fungus of Pityriasis capitis simplex. It is 
 very similar to the foregoing, and is likewise seated 
 
60 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 in the horny layer of the epidermis, on which it 
 produces a roughness in the form of dusty pellicles. 
 It penetrates the hair-follicles, but not deeply, and 
 only in the vicinity of the point at which they emerge. 
 The spores of which it entirely consists are generally 
 of an elongated form, and give off buds. 
 
 According to Mallassez, this fungus is the prin- 
 cipal cause of alopecia; that is, the shedding of 
 
 Fig. 32. Epidermic CP!! of skin 
 covered with hair, affected l>y 
 Pitt/riasis simplex, and covered 
 with spores ( x 1000 diam.). 
 
 Fig. 33. Isolated spores, taken 
 from pellicles of PUyriasis 
 capitis simplex: a, full spores; 
 b, empty spores ; c, full spores 
 budding ; d, the same empty 
 (x 10UO diam.) 
 
 hair, and the baldness which eventually ensues from 
 it. It acts in two ways : (1) its presence and multi- 
 plication disintegrate the epithelial layers ; (2) the 
 foreign body irritates the epidermis, producing exces- 
 sive activity in the evolution of cells, and consequently 
 the incessant desquamation which is the most apparent 
 symptom of the disease. The shedding of hair is chiefly 
 due to obstruction in that portion of the hair-follicle 
 which underlies the orifice of the sebaceous glands, and 
 
PARASITIC FUNGI AND MOULDS. 61 
 
 this checks the regular development of the hair. The 
 consequent irritation of the follicle produces hyper- 
 trophy; this leads to the shrinking and finally to 
 the obliteration of the follicle, and after languishing 
 for a while, the hair falls off. 
 
 Thrush (Oidium albicans)* This fungus generally 
 appears on the mucous membrane of the mouths of 
 infants, especially of those brought up by hand, and 
 which have been accustomod to the use of a sucker. 
 The saliva becomes acid, and the white spots which 
 constitute thrush (Fig. 34?) appear in several places, 
 especially on the tongue, the gums, and the soft 
 palate. 
 
 This plant is composed of two elements: of hyphse, 
 and of spores, which adhere closely to the mucous 
 membrane. The spores become elongated and con- 
 verted into hyphse, which are segmented and ramified 
 as their length increases ; and they produce spores by 
 division of the terminal cell, or sometimes by endo- 
 genous formation within the hyphse. 
 
 Thrush sometimes occurs in adults in certain 
 diseases, such as phthisis and typhoid fever, especially 
 when the patient eats little and is imperfectly 
 nourished, which is frequently the case in serious or 
 protracted illness. 
 
 It is easy to destroy thrush by washing the 
 mouth with Vichy water, or a solution of bicarbonate 
 
 * Oidium allrimns, Robin ; Sdccharomyres albicans, Reos ; Sacch. 
 mycoderma, Grawitz. (See chapter on the Polymorphism of Microbes.) 
 
62 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 of soda, which neutralizes the acidity of the saliva. 
 It is, above all, essential that the feeding-bottle, all 
 the utensils employed for the infant, and the infant 
 itself, should be kept perfectly clean; and, unfortu- 
 nately, this condition is too rarely fulfilled, especially 
 
 Fig. 34. Oidium albicans, or Saccharomj/ces mycolerma: d, much-branched myce- 
 lium ; g t chaplet or torula of spores, giving birth at/, k to the mycelium. 
 
 among the working classes in towns, and districts in 
 which children are usually put out to nurse. The 
 feeding-bottle in use in such cases generally smells 
 so sour as to be offensive to every one who is not 
 
PARASITIC FUNGI AND MOULDS. 63 
 
 accustomed to it, and under these conditions thrush 
 is almost certainly developed, so that few children 
 escape an attack. It is not generally dangerous, yet 
 it may, in some cases, compromise the health, and 
 even cause the death of the child. In addition to care 
 about cleanliness, a little pinch of bicarbonate of soda 
 may be put in the feeding-bottle; this prevents the 
 milk from turning sour. 
 
 Onychomycosis. This disease, which attacks the 
 nails of men and the hoofs of uni-ungulates (the horse, 
 the ass, and the mule), is caused by a parasitic fungus 
 of the genus Achorion (A. keratophagus). In man it 
 is termed dry caries, and it is a fungus which is readily 
 transferred from man to the animals with which he 
 has to do, just as Achorion Schoenlenii of ringworm 
 passes from man to the dog, cat, rat, horse, ox, and 
 perhaps even to rabbits and gallinaceae. 
 
 In uni-ungulates the fungus is introduced into the 
 cracked and superficial layer of the hoof through its 
 fissures. In order to destroy it, this external layer 
 must be removed, and for greater security an anti- 
 parasitic treatment should be used. 
 
 This remedy cannot be applied to the human subject 
 without causing considerable pain ; yet the nail may 
 be pared and scraped, and the anti-parasitic remedy 
 can then be applied. 
 
 Prevention and Cure of S^ in- diseases. The general 
 custom of going to a common barber to have the hair 
 dressed or cut must conduce to the dissemination of 
 
64 MICROBES, FERMENTS, AND MOULDS. 
 
 the fungi which attack those parts of the skin clothed 
 with hair ; the brush, the comb, or razor which passes 
 successively and on the same day over ^hundreds of 
 heads or chins must necessarily, if only in one case 
 out of ten, carry the spores of the parasite from one 
 person to another. 
 
 The parasitic diseases of the hair are extremely 
 persistent, and precautions as to cleanliness will not 
 always effect a cure. The mixtures sold by hair- 
 dressers under the name of capillary water, lotion to 
 eradicate scurf, etc., should all be rejected. Experience 
 shows that wetting the head often favours the 
 development of the fungus, which may, indeed, remain 
 stationary for two or three days, but which becomes 
 more vigorous as soon as the head is dry. Sulphur 
 and its compounds are successful in such cases, as 
 well as in the parasitic diseases of plants. It would 
 be best to apply this remedy in the form of a dry, 
 impalpable powder, as in the application of sulphur 
 to the vine, but this cannot be done without in- 
 conveniences to which the persons affected do not 
 readily submit; it might, however, be tried by those 
 whose hair is naturally greasy. In other cases, and 
 especially in those in which the hair is dry, as it 
 usually is in persons affected by Pityriasis capitis, 
 pomades must be used, although it has been asserted, 
 but not proved, that fatty substances afford nourish- 
 ment to the fungus. 
 
 However this may be, the pomade for which we 
 
PAEAS1TIC FUNGI AND MOULDS. 65 
 
 subjoin the recipe has been very successful in pity- 
 riasis, and in all the infantile forms of ringworm, 
 including that which occurs in teething, and which 
 may be safely treated, in spite of prejudices to the 
 contrary : 
 
 Turbith mineral (tri-mercuric sulphate"* ... 1 to 2 grs. 
 Benzoinated lard ... ... ... 15 grs. 
 
 This pomade is lemon-coloured ; it will assume a 
 flesh-colour by the addition of a few drops of red 
 litmus, and may be scented to the taste of the person 
 who is to make use of it. In ordinary cases of 
 pityriasis, it need only be applied every eight or 
 fifteen days. It is indispensable to wash the combs 
 and brushes in a solution of potash or ammonia, lest 
 the benefit of the treatment should be lost by re- 
 infection. In the case of true ringworm, especially in 
 adults, a much more energetic treatment is necessary, 
 for- which medical advice is required. 
 
66 MICBOBES, FERMENTS, AND MOULDS. 
 
 CHAPTER II. 
 
 FERMENTS AND ARTIFICIAL FERMENTATIONS. 
 
 I. WHAT is FERMENTATION ? 
 
 CHEMISTS define fermentation in these words : " Fer- 
 mentation takes place wherever an organic compound 
 undergoes changes of composition, under the influence 
 of a nitrogenous organic substance called a ferment, 
 which acts in small quantities and yields nothing to 
 the fermented substance " (A. Gautier). 
 
 This nitrogenous substance, termed a ferment, is 
 regarded by naturalists as an organized living being, 
 either animal or vegetable. This was demonstrated 
 by the researches of Cagnard de La Tour, of Turpin, 
 of Dumas, and more recently by the splendid achieve- 
 ments of Pasteur. It is now proved that the artificial 
 fermentation which takes place .in the manufacture 
 of wine, beer, etc., is produced by small microscopic 
 plants, called ferments or yeast. 
 
 The chemical transformation resulting from them 
 might be obtained without the intervention of yeast, 
 
FERMENTS AND ARTIFICIAL FERMENTATIONS. 67 
 
 properly so called, either by means of a nitrogenous 
 substance of animal origin (Berthelot), or by other 
 chemical and physical processes which we shall 
 presently mention. But it may be questioned whether 
 the nitrogenous substance of animal origin, which 
 Berthelot considers to be dead, does not contain a 
 living ferment. This is not admitted to be the case 
 by Bechamp, whose theory will be given further on. 
 
 Whenever fermentation is produced solely by the 
 influence of physical and chemical agents, the action 
 is very slow. But it is, on the other hand, very rapid 
 when effected by living ferments or yeast, and it is 
 also much less costly, so that the latter mode of 
 fermentation is. preferred by manufacturers. Yeast is, 
 therefore, the true agent in artificial fermentations. 
 
 All the saccharine liquids which contain glucose or 
 grape sugar, or a sugar which can be transformed into 
 glucose, and also all nitrogenous substances, phos- 
 phates, and ammoniacal salts, produce alcohol at a 
 temperature varying between 25 and 100, and the 
 yeast of beer (of which the spores are carried through 
 the air) appears and is developed at the same time; 
 this occurs in the juice of grapes, beetroot, sugar- 
 cane, etc. The alcoholic liquids thus produced are 
 then subjected to distillation in order to extract the 
 alcohol. The transformation of alcohol into vinegar 
 is produced by another ferment. 
 
 Fermentations are very common in nature. The 
 transformation of sugar into lactic, butyric, and 
 
 TIISITY; 
 
68 MICROBES, FERMENTS, AND MOULDS. 
 
 caproic acids, under the influence of nitrogenous 
 substances and of the air; the change into glucose 
 of gums, of starch, of dextrine, of sucrose, and mannite ; 
 the transformation of these substances into each other 
 under the influence of living agents, or of those 
 belonging to a living organism; the transformation 
 of such glucosides as populin, salicin, tannin, etc., 
 into sugar, or into neutral or acid substances; all 
 these phenomena are fermentations (A. Gautier). 
 
 We may even go further. The germination of 
 seeds and the ripening of fruit are accompanied by 
 phenomena of the same order. In animals, gastric, 
 pancreatic, and intestinal digestion, together with other 
 changes connected with nutrition and assimilation 
 which take place in the blood and in all the organs, 
 may be considered as true fermentations. In this case 
 the cells of our tissues and the blood-corpuscles play 
 the part of yeast in effecting alcoholic fermentations. 
 
 Finally, the miasmatic, virulent, and contagious 
 diseases, which we shall study in another chapter, 
 are also caused by changes in the blood and in the 
 other fluids of the system, and should be considered 
 as fermentations, produced by minute microscopic 
 organisms analogous to ferments, and which are, as 
 we shall presently show, bacteria or microbes, strictly 
 so-called. The putrefaction of dead bodies is also 
 a fermentation. 
 
 We shall, in this place, only consider the fernien- 
 tat ions which are used in manufactures. 
 
FERMENTS AND ARTIFICIAL FERMENTATIONS. 69 
 
 History. The precise knowledge of the nature of 
 fermentation is of comparatively recent date. The 
 ancients, indeed, seem to have had an idea, however 
 vague, of this phenomenon, which was in their case 
 connected with the erroneous theory of spontaneous 
 generation. We all know the fable of the bees, born 
 from the putrefying body of a slain bull, which forms 
 one of the chief episodes of the Metamorphoses of 
 Ovid, and of the fourth book of Virgil's Georgics. 
 Aristotle says that, by means of heat, one living being 
 may have its birth in the corruption of another. . . . 
 Fermentation is, in fact, always accompanied by an 
 evolution of heat. The same idea was revived in the 
 Middle Ages, and during the Renaissance by alchemists 
 and physicians. Van Helmont, who lived early ii& 
 the seventeenth century, goes so far as to say, " It is 
 true that a ferment is sometimes so bold and enter- 
 prising as to form a living being. In this way, 
 lice, maggots, and bugs, our associates in misery, 
 have their birth, either within our bodies or in our 
 excrement. You need only close up a "Vessel full 
 of wheat with a dirty shirt, and you will see rats 
 engendered in it, the strange product of the smell 
 of wheat and of the animal ferment attached to the 
 shirt." 
 
 Beside these singularly rash and purely fanciful 
 assertions, which show that imagination was allowed 
 in those days to play a much too important part 
 in natural science, we find a theory of the fermenta- 
 
70 MICROBES, FERMENTS, AND MOULDS. 
 
 tion in putrefying bodies which would not be rejected 
 by modern naturalists and chemists. 
 
 "After death . . . the foreign ferments, which are 
 always intent on change, are borne through the air 
 and introduce corruption into dead matter ... at 
 least, unless the flesh is combined with certain sub- 
 stances, such as sugar, honey, or salt. It is, therefore, 
 these ferments, attacking whatever matter is deprived 
 of life, which disintegrate and prepare it to receive a 
 new soul (or fresh life)." 
 
 Linmeus, again, says that " a certain number of 
 diseases result from animated, invisible particles, which 
 are dispersed through the air. . . ." Boerhave, in 1693, 
 distinguished three kinds of fermentation : alcoholic, 
 acetous, and putrefactive. But we must come down 
 to the beginning of this century in order to find more 
 definite ideas respecting the organic nature of ferments. 
 
 In 1813, a chemist called Astier asserted that 
 every kind of germ from which ferments proceed is 
 carried by the air; that this ferment, of animal 
 nature, is alive, and is nourished at the expense of 
 the sugar, and hence results disturbance of the 
 equilibrium between the elements of sugar. 
 
 Subsequently, in 1837, Cagnard de La Tour* de- 
 clared yeast to be a collection of globules which are 
 multiplied by budding; and in the following year 
 Turpin described the yeast of beer as a vegetable, 
 microscopic organism, which he termed Torula cere- 
 visice (Fig. 35). 
 
FERMENTS AND ARTIFICIAL FERMENTATIONS. 71 
 
 Chemists were at first unwilling to admit the 
 important part played by yeast in fermentations, and 
 in order to explain it, they assumed the existence 
 of a very obscure physico-chemical 
 phenomenon, to which the name 
 of catalysis, or action by presence, 
 was given. But in 1843 an illus- 
 trious French chemist, Dumas, 
 clearly explained the physiological 
 
 Fig. 35. ibrvla (Saciha- 
 
 functlOQ Of the living ferment, Or romyces) cerevigu*, yeast 
 
 of beer ( x 400 diam.). 
 
 yeast. 
 
 " Fermentations," he writes, " are always pheno- 
 mena of the same order as those which characterize 
 the regular accomplishment of the acts of animal life. 
 They take possession of complex, organic substances, 
 and unmake them suddenly or by degrees, restoring 
 them to the inorganic state. Several successive fer- 
 mentations are, indeed, often required to produce the 
 total effect. The ferment appears to be an organized 
 being ; . t . the part played by the ferment is played 
 by all animals, and by all but the green parts of 
 plants. All these beings and organs consume organic 
 substances, multiply and restore them to the simplest 
 forms of inorganic chemistry." 
 
 Finally, Pasteur's memorable labours, which he 
 began to publish in 1857, confirmed the new theory 
 of fermentation, which no one now doubts. Pasteur 
 states that every fermentation has its specific ferment ; 
 in all fermentations in which the presence of an or- 
 
72 MICROBES, FERMENTS, AND MOULDS. 
 
 ganized ferment has been ascertained, that ferment is 
 necessary. This minute being produces the transforma- 
 tion which constitutes fermentation by breathing the 
 oxygen of the substance to be fermented, or by ap- 
 propriating for an instant the whole substance, then 
 destroying it by what may be termed the secretion 
 of the fermented products. Three things are necessary 
 for the development of the ferment: nitrogen in a 
 soluble condition, phosphoric acid, and a hydrocarbon 
 capable of fermentation (such as grape sugar). Finally, 
 every organized ferment of fermentation or putrefac- 
 tion is borne about in the air, as may be shown by 
 experiments. 
 
 II. VEGETABLE NATURE OF FERMENTS OR YEAST. 
 
 Yeast, or ferments, are in their organization 
 closely allied to the fungi of which we spoke in the 
 preceding chapter under the name of Microsporon. 
 Many botanists still assign them to the class of fungi 
 under the name of Saccharomycetes ; yet, as they live 
 in liquids, or at any rate on damp substances, like the 
 Algae, which are species of water-fungi, it is now 
 almost agreed to place them in the same category as 
 the latter, which they resemble in their whole organi- 
 zation, except in the absence of chlorophyl. This 
 last characteristic, the only one by which they ap- 
 proximate to fungi, is common both to them and to 
 microbes or bacteria, which are only ferments of 
 
FERMENTS AND ARTIFICIAL FERMENTATIONS. 73 
 
 smaller size, and which are now also placed in the 
 class of Algae. We shall return to this subject when 
 we come to, speak of bacteria. 
 
 The structure of ferments is very simple : each 
 plant is generally composed of a single cell, spherical 5 
 elliptical, or cylindrical, formed of a thin cell- wall, con- 
 taining a granular substance called protoplasm, which 
 is the essential part of the plant. These cells have an 
 average diameter of ten micro-millimetres. They 
 grow and bud, and when one of them reaches a certain 
 size, a median constriction occurs ; it divides into two 
 parts, resembling the mother cell, and these some- 
 times separate, sometimes remain united in a group 
 or chaplet (Fig. 35). This mode of multiplication 
 continues as long as the plant remains in a liquid 
 favourable to its nutrition. But if its development is 
 hindered, if, for example, the liquid dries up, the pro- 
 toplasm contained in each cell contracts, and is 
 transformed into one or more globules, which are 
 the spores or endogenous reproductive organs of the 
 plant. These spores may remain undeveloped for 
 a long while, may become perfectly dry, and may 
 even be subjected to a very high temperature, without 
 losing the power of germination when they are again 
 placed in conditions favourable to their development. 
 They then reproduce the plant from which they had 
 their birth, and are multiplied in the same manner.* 
 
 * For further details on ferments and fermentations, see 
 Schutzeuberger's work on the subject. 
 
MICROBES, FERMENTS, AND MOULDS. 
 
 III. WINE FERMENTS ; ALCOHOLIC FERMENTATION. 
 
 The commonest ferment of wine is, according to 
 Pasteur, Saccharomyces ellipso'ideus (Figs. 36, 37, 38), 
 which must not be confounded with Kutzing's 
 Cryptococcus vini, since the latter has nothing to do 
 
 Fig. 36. Saccharomyces tllipsoideus, wine ferment, in process of budding 
 (X600 diam.). 
 
 with alcoholic fermentation. This ferment is found 
 on the grape, and is thus introduced into the ferment- 
 
 Fip tf.Sacch. ellipsoideus : 
 development of spores ( x 
 400 diam.). 
 
 Fig 38. Sacch. ellipso'ideus: 
 germination of spores ( x 400 
 diam.). 
 
 ing- vats. The adult cells are of an elliptic form, and 
 are six micro-millimetres in length, by four or five in 
 width. They bud, and are reproduced in the way 
 already indicated, which is common to all ferments. 
 
FERMENTS AND ARTIFICIAL FERMENTATIONS. 75 
 
 Sacch. Pastorianus (Rees) is probably only a 
 variety of the foregoing (Fig. 39), differing a little 
 in the form of the cells, which are elongated, pyriform, 
 or club-shaped. 
 
 Lastly, Sacch. conglomerate is somewhat rare. It 
 is found in the grape-must when fermentation is 
 nearly over (Fig 40). It is so called because the new 
 cells are conglomerated, instead of being arranged in 
 a chaplet. 
 
 We must now notice the other ferments which 
 
 Fig. 39. Sacch. Paxtori- Fig. 40. Sacch. conglvm- Fig 41. Sacch. exiguus 
 anus ( x 400 diain.). eratus ( x 600 diam.). C x 350 diam ). 
 
 are found, like those given above, in fermented syrups, 
 and which may also produce the alcoholic fermenta- 
 tion of wine. Such is Sacch. exiguus (Fig. 41), of 
 which the cells are much smaller than in the fore- 
 going, since they are only three micro-millimetres 
 by two and a half micro-millimetres. 
 
 The apiculate ferment, of which Engel has made 
 a separate genus, under the name of Carpozyma 
 apiculata, is the alcoholic ferment which appears to 
 be the most widely diffused in nature (Fig. 42). It 
 is found on all kinds of fruit, especially upon berries 
 and drupes, as well as upon most of the fruit-musts 
 
7G 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 which are in process of fermentation. It has likewise 
 been observed in Belgium upon beer. It is generally 
 the first to appear and bud in the must. Its name is 
 
 Fig. 42. Sacch. apiculata (Carpjzyma), icriucnt of fruits (x6JU diam.). 
 
 due to the characteristic form of its cells, which are 
 formed like rape-seed, or apiculated at both extremi- 
 ties of their large axis. 
 
 In the fermented must of red wine we find, 
 together with Sacch. ellipsoideus, a somewhat dif- 
 ferent form, which is perhaps only a variety Sacch. 
 Reesii. 
 
 We must also mention another alcoholic ferment, 
 Sacch. mycoderma, wine or beer flowers, which con- 
 
 Fig. 43.Succh. mycoderma, or 
 wine-flowers ( x 350 diam.). 
 
 , 
 
 ig 44. Different forms of Sacch. 
 mycoderma. 
 
 stitute the white pellicle often seen on bottled wine 
 (Figs. 43, 44). Pasteur has shown that, under certain 
 
FERMENTS AND ARTIFICIAL FERMENTATIONS. 77 
 
 circumstances, Mycoderma, vini can produce alcoholic 
 fermentation ; this is easily shown by adding it to a 
 saccharine solution, in which it soon produces fermenta- 
 tion. It appears on the surface of all alcoholic liquids 
 which are exposed to the air, when fermentation is 
 over or nearly over. Its growth is very rapid ; a few 
 cells are enough to cover the surface in the course of 
 forty-eight hours with a thin white or yellow pel- 
 licle, which is at first smooth, and then wrinkled. This 
 implies, according to Engel's estimate, that a single 
 cell has produced 35,000 others in this short time. 
 
 Most of these different forms are probably only 
 different stages of development of a limited number 
 of species, since ferments are as polymorphic as 
 microscopic fungi. 
 
 We have said that before they are found in the 
 must of wine or fruits, the ferments fasten in a 
 dormant state on the epidermis of the fruit, by which 
 means they are introduced into the liquid about to be 
 fermented. We see how the spores are transported 
 through the air until they rest on the downy surface 
 of a drupe or berry. But it has been asked what 
 becomes of this ferment between last year's vintage 
 and the succeeding summer, and in what way it 
 passes the winter. 
 
 According to Hansen's researches, Sacch. apiculata, 
 which is, for instance, found upon gooseberries, is 
 washed off them by the rain, dispersed by the wind, 
 and falls to the ground with the fruit, where it 
 
78 MICROBES, FERMENTS, AND MOULDS. 
 
 remains buried through the winter as a dormant 
 spore, in order to return to the same fruit when it 
 has ripened in summer. It can only be borne 
 through the air when the ground is completely dried 
 
 In the same way, the ferments of wine, after 
 having passed through the bodies of men and animals, 
 pass the winter on the dungheap. This revelation 
 may not be pleasing to drunkards, but it will not 
 surprise those who are acquainted with the habits of 
 cryptogams in general, and of fungi in particular. 
 Brefeld has found these ferments during the winter, 
 especially in the excrement of herbivorous animals, 
 and on the dungheap. 
 
 The manufacture of wine is too well known to 
 require description ; we need only remind our readers 
 that alcoholic fermentation essentially consists in the 
 transformation of glucose, or grape-sugar, into alcohol 
 and carbonic acid. The latter, given off in the form 
 of gas, produces the ebullition or effervescence which 
 characterizes fermentation, and to which its name is 
 due. Sugar or glucose is, therefore, the essential 
 nutriment of all yeast-plants, and the indispensable 
 element of these fermentations, of cider, beer, and all 
 fermented liquors, as well as of wine. 
 
 IV. BEER-YEAST. 
 
 The yeast of beer, or Sacch. cerevisics, was the 
 earliest known and the most carefully observed of 
 
FERMENTS AND ARTIFICIAL FERMENTATIONS. 79 
 
 all the ferments, and may be regarded as the type of 
 the family. Its cells are round or oval, from eight 
 to nine micro-millimetres in their longest diameter, 
 isolated or united in pairs (Fig. 35). 
 
 When these cells are deposited in a saccharine 
 liquid, which is therefore susceptible to fermentation, 
 vesicular swellings, filled with protoplasm at the 
 expense of the mother cell, may be observed at one 
 
 Fig. 45. Yeast of superior beer 
 budding (x 4uu diam.). 
 
 Fig 4(j. Spores of beer-yeast, in 
 different phases of development. 
 
 or two parts of the surface of the cell ; these swellings 
 increase, acquire the size of the mother cell, and then 
 contract at their base (Fig. 45). They generally arise 
 on the sides of the cell, more rarely on its extremities. 
 The new cells thus formed soon separate from the 
 mother cell, and the protoplasm given up to its off- 
 spring by the latter is replaced by one or two empty 
 spaces, termed vacuoles. When yeast is not in a 
 liquid susceptible to fermentation, it can remain for 
 a longer or shorter time without modification. If 
 abruptly deprived of all nutriment, and especially of 
 sugar, and placed in a sufficiently moist atmosphere, 
 
80 MICROBES, FERMENTS, AND MOULDS. 
 
 spores may bo produced (Fig. 46). It is rather 
 difficult to perform the experiment with success ; the 
 ferment must be frequently washed with distilled 
 water, as it may otherwise putrefy, instead of fruc- 
 tifying (Schutzenberger). 
 
 Let us briefly describe the process by which the 
 fermented liquor termed beer is obtained The barley 
 which constitutes its essential principle does not 
 contain sugar ; but when it has germinated it contains 
 a substance termed diastase, under the influence of 
 which the starch of barley can be converted into 
 glucose. 
 
 The barley, which has been moistened in order to 
 make it swell and germinate, is spread in a thin layer 
 on hurdles, at a temperature of about 15: this opera- 
 tion is called malting. It is generally performed in 
 spring, in order to ensure the necessary warmth 
 and moisture, and March beer is considered the best. 
 When the sprout attains to two-thirds of the length 
 of the grain, germination is arrested by drying the 
 grains on a stove, and they are then ground to 
 powder and become malt. This malt is then steeped 
 in water at the temperature of 60 and by the 
 action of the diastase the starch becomes glucose. 
 This saccharine fluid or wort is boiled with hops, 
 which are now added, not only to give a bitter and 
 aromatic taste, but also to preserve it. This infusion 
 of malt and hops is concentrated and cooled, and beer- 
 yeast, the product of previous operations, is added in 
 
FERMENTS AXD ARTIFICfAL FERMENTATIONS. 81 
 
 order to establish fermentation. The yeast is procured 
 by collecting the scum of fermented beer and straining 
 it into bags. 
 
 In Belgium, the wort is allowed to stand until the 
 spontaneous development of fermentation takes place ; 
 but in France and Germany the ferment is generally 
 added. In this case two methods are in use, fermenta- 
 tion from above, and fermentation from below ; and this 
 enables us to distinguish two kinds 
 of yeast, that of superior, and that of 
 inferior beer (Figs. 45, 47). 
 
 In superior beer, the saccharifica- 
 tion of the starch of malt is effected 
 by successive steepings in casks at 
 the relatively high temperature of 
 from 15 to 18. As the yeast is 
 formed, it gradually issues from the 
 bung-holes in the upper part of the 
 cask ; hence its name. In England, large open vats 
 are used : the yeast rises to the top, and is removed 
 with skimmers. 
 
 In the manufacture of inferior beer, saccharifica- 
 tion is effected by steeping the malt in open vats at 
 the lower temperature of from 12 to 14. The 
 yeast is deposited at the bottom of the vats in a 
 doughy and tenacious mass. When the first and 
 most active fermentation is at an end, the clear liquid 
 is drawn off and put into casks, bottles, or pitchers, 
 and as the separation of the yeast is not yet complete, 
 7 
 
 Fig. 47. Yeast of in- 
 ferior hCT i<i process 
 of budding (x 400 
 diam.). 
 
82 MICROBES, FERMENTS, AND MOULDS. 
 
 it continues to act on the unmodified sugar. The 
 production of fresh yeast makes the liquor thick, and 
 the amount of alcohol and of carbonic acid increases 
 in accordance with the time for which it is kept, after 
 being bottled or put in closed casks. 
 
 The manufacture of most fermented liquors 
 resembles that of wine or beer ; that of cider is very 
 simple, and consequently approximates to the 'manu- 
 facture of wine. The apples are cut and crushed, and 
 remain in the vats until fermentation is over; the 
 liquid is then separated from the solid residue, and 
 put into casks or bottles. 
 
 V. CONCERNING SOME OTHER FERMENTED LIQUORS. 
 
 There are many other fermented liquors made in 
 various countries with substances derived from the 
 animal or vegetable kingdom. 
 
 In France, cider or perry is sometimes made from 
 pears or crab-apples. 
 
 What the French call boissons are cheap fermented 
 liquors, prepared from dried raisins or aromatic sub- 
 stances, such as the dried fruit of the coriander, to 
 which water sweetened with treacle is added. Fer- 
 mentation is usually effected by germs borne by the 
 air, or by those introduced by the coriander and the 
 other ingredients of the liquor; or it may be hastened, 
 as in Belgian beer, by the addition of beer-yeast or 
 baker's yeast. It is effected by the transformation of 
 
FERMENTS AND ARTIFICIAL FERMENTATIONS. 83 
 
 the sugar into alcohol and carbonic acid, and this con- 
 stitutes an aerated drink, which is very agreeable when 
 well made, and especially if it has been carefully 
 bottled before fermentation is over. 
 
 Koumiss is made of soured and fermented mare's 
 milk, and is much used in Russia as a refreshing 
 drink, from which an alcoholic liquor may be distilled. 
 
 Many kinds of brandy are made from the fruits 
 and seeds of different plants. Kirschwasser is the 
 alcohol produced by distilling cherries or geans ; rum 
 is made from sugar-cane, arrack from rice. Gin, 
 distilled from the juniper-berry, is largely consumed 
 by the labouring classes in England, as corn-brandy is 
 in the French drinking- shops. 
 
 The savage Malay and Polynesian races prepare 
 fermented liquors from the sap of various plants. 
 Such is kava, made from masticated roots, and steeped 
 in an infusion of Piper methysticum. In this case, 
 the ptzalin, a ferment contained in the human 
 saliva, transforms the fecula into a sugar susceptible 
 to fermentation. The operators sit round a large 
 vessel containing the roots steeped in water, and each 
 man takes a piece, which he masticates conscientiously 
 until it is sufficiently impregnated with the salivary 
 ferment. This process is revolting to our ideas, and 
 few Europeans would touch a liquor which has been 
 prepared in such a way ; but this is doubtless an 
 educated prejudice which would not occur to a native 
 of Oceana. 
 
84 MICROBES, FERMENTS, AND MOULDS. 
 
 The dragon-trees (Dracoena terminalis and Z). 
 Australis) also possess a feculent root, from which a 
 fermented liquor is extracted in the same manner by 
 the Sandwich Islanders. 
 
 VI. THE LEAVEN OF BREAD. 
 
 Bread is leavened in order to make it porous and 
 more digestible. According to Engel, the microbe of 
 baker's yeast is Sacch. minor, resembling that of beer- 
 yeast, only more minute. Most of the yeasts which 
 we have examined contain a great variety of microbes. 
 However this may be, the fermentation of bread, like 
 other fermentations, sets free carbonic acid gas, and 
 this raises the dough and makes it light. 
 
CHAPTER III. 
 
 MICROBES, STRICTLY SO CALLED, OR BACTERIA. 
 
 I. THE VEGETABLE NATURE OF MICROBES. 
 
 As we have seen in the preceding chapter, there is 
 no well-defined limit between ferments and bacteria, 
 any more than between ferments and fungi, or, again, 
 between fungi and bacteria. Their smaller size is the 
 principal difference which separates bacteria from 
 ferments, since in other respects these two classes are 
 for the most part alike in form and organization. There 
 are bacteria of large size, such as LeptotJirix buccalis, 
 so frequently found in the mouth even of a healthy 
 man, which much resembles in its mode of growth 
 some of the lower fungi, such as Oidium albicans. 
 Yet the latter is regarded as a fungus, and the former 
 as an alga, by our best cryptogamous botanists. It 
 may, however, be said that the two classes of algae and 
 fungi are connected with each other by their lower 
 forms, and probably have a common origin ; just as the 
 two great organic kingdoms are connected by their 
 
86 MICROBES, FERMENTS, AND MOULDS. 
 
 lower forms, which have been by some united in the 
 kingdom Protista. 
 
 Microbes, or .bacteria (Sdiizophyta or Schizomycetes'), 
 appear, in liquids examined under the microscope, as 
 small cells of a spherical, oval, or cylindrical shape, 
 sometimes detached, sometimes united in pairs, or 
 in articulated chains and chaplets (Fig. 
 48). The diameter of the largest of these 
 cells is two micro-millimetres, and that 
 of the smallest is a fourth of that size, 
 so that at least 500 of the former and 
 2000 of the latter must be placed end 
 fei ent n forms (l of to end in order to attain the length of 
 
 bacteria, detach- .... TI n p i ji 
 
 ed or in chapiets a millimetre. It is tneretore plain that a 
 
 (highly magni- 
 fied)- magnifying power of 500 to 1000 dia- 
 meters, or even still higher, is required to make these 
 beings clearly visible under the microscope. 
 
 One very common bacterium may be found every- 
 where, and can be easily procured for microscopic 
 observation : Bacterium termo, or the microbe of im- 
 pure water. This bacterium is not injurious to health, 
 since there is no potable water in which it is not 
 found in greater or less quantity. In order to obtain 
 numerous specimens, it is enough to take half a glass 
 of ordinary water from a spring or river, and to leave 
 it for some days on a table or chimney-piece, the 
 vessel being uncovered to allow the access of air. We 
 may soon observe that a thin coating is formed on 
 the surface of the water, which looks like a deposit 
 
MICROBES, OR BACTERIA. 87 
 
 of fine dust ; this dust consists of myriads of bacteria. 
 If we take a drop of this water and place it under 
 a cover-glass, in order to examine it under a micro- 
 scope with a magnifying power of about 500 dia- 
 meters, we shall, as soon as the instrument is properly 
 focussed, see a really surprising spectacle. 
 
 The whole field of the microscope is in motion ; 
 hundreds of bacteria, resembling minute transparent 
 worms, are swimming in every direction with an un- 
 
 
 
 '*"i 1 In n?a- U ^ 
 
 ^ 
 
 & 
 
 \ 
 
 Fig. 49. Bact. ttrmo in different stages of development, a-h (much magnified \ 
 
 dulatory motion like that of an eel or snake. Some 
 are detached, others united in pairs, others in chains 
 or chaplets or cylindrical rods which are partitioned 
 or articulated (Fig. 49) ; these are only less mature or 
 younger than the first. Finally, we see a multitude of 
 small globules which result from the rupture of the 
 chaplets. All these forms represent the different 
 transformations of Bacterium termo, or the microbe of 
 
88 MICROBES, FERMENTS, AND MOULDS. 
 
 putrefaction. Those which are dead appear as small, 
 rigid, and immovable rods. 
 
 In observing the lively movements of these minute 
 organisms, we might be tempted to regard them as 
 animals. But we know that movement, taken by 
 itself, is not peculiar to the animal kingdom. Setting 
 aside the movement which can be provoked in the 
 mimosa and in many higher plants, it is well to 
 remember that many of the lower plants are capable 
 of motion : this is the case with Diatomacece, in which 
 the presence of chlorophyl incontestably proves their 
 vegetable nature. The spores of plants of a much 
 higher organization, such as ferns and mosses, have the 
 power of swimming in the water, just as bacteria have : 
 this has procured for them the name of Zuospores, 
 although many of them contain chlorophyl. 
 
 The movements of bacteria are, like those of zoo- 
 spores, due to the presence of vibrating cilia, which 
 are inserted at both extremities, or only at the hinder 
 extremity of the microbe, and which form organs of 
 propulsion analogous to the tails of tadpoles. These 
 organs are very transparent and are difficult to see in 
 the living subject, even with the strongest magnifying 
 power, on account of the rapidity of their movements. 
 But their existence has been ascertained by the use of 
 staining fluids, and above all by micro-photography. 
 
 If, however, we analyze the mode of motion in 
 Bacterium termo, and compare it with the movements 
 of the ciliated or flagellated infusoria which may often 
 
MICROBES, OR BACTERIA. 80 
 
 be seen swimming with it in the field of the microscope, 
 we are struck by the difference. Infusoria come and 
 go, swiftly or slowly they go back or move to the 
 right or left ; in a word, their movements seem to be 
 actuated in some sense by will. Nothing like this 
 is observed in the bacterium. The undulatory move- 
 ment by which it is animated is always the same, and 
 impels it straightforward, like a stone sent from a 
 sling; it never voluntarily goes back nor out of its 
 course, but only under the influence of a foreign im- 
 pulse, such as contact with another bacterium, when it 
 rebounds, just as a projectile may rebound from a wall. 
 On encountering an obstacle, the bacterium remains 
 indefinitely undulating before it, without ever pausing 
 or showing signs of fatigue, until some external cause 
 comes to release and send it to the right or left. We 
 may often see a tangled mass of bacteria, perhaps 
 adhering by their cilia or by some other substance, in 
 which all the individuals continue to undulate until 
 the rupture of the mass permits them to depart in all 
 directions. These organisms are therefore plants in the 
 character of their movements, as well as in the rest of 
 their organization. 
 
 In bacteria each cell consists of a cellulose wall, 
 containing protoplasm, as we saw was the case in fer- 
 ments. The multiplication by fission is effected in 
 precisely the same way in bacteria and ferments, and 
 so also is the formation of spores. Under certain 
 circumstances, when the liquid on which they subsist 
 
90 MICROBES, FERMENTS, AND MOULDS 
 
 is dried up, the protoplasm contracts and forms spores, 
 which, when set at Hberty by the rupture of the cell- 
 wall, germinate and give birth to fresh bacteria. The 
 only difference consists in the fact that ferments may 
 produce several spores in each cell, while bacteria 
 never produce more than one. 
 
 Bacteria were, as we have already said, for a long 
 while classed with fungi under the name Schizomycetes. 
 But recent researches into their organization, and more 
 especially into their mode of reproduction, show that 
 they resemble a group of inferior algse termed Phy- 
 cochromycece, which includes Oscillaria, Nostocs, and 
 Chroococcus, species generally furnished with chloro- 
 phyl. Bacteria represent a similar group devoid of 
 chlorophyl. Zopf, in a treatise recently published, goes 
 still further: he asserts that the same species of alga 
 may at one time be presented in the form of a plant 
 living freely in water or damp ground by means of 
 chlorophyllaceous protoplasm, and at another in the 
 form of a bacterium or parasitic microbe, devoid of 
 chlorophyl, and nourished at the expense of organic 
 substances which have been previously elaborated by 
 animals or plants, thus accommodating itself, accord- 
 ing to circumstances, to two very different modes of 
 existence. 
 
MICROBES, OR BACTERIA. 91 
 
 II. CLASSIFICATION OF MICROBES, OR BACTERIA. 
 
 It is very difficult to make any natural classifica- 
 tion of the organisms which belong to the group of 
 microbes ; we have, in fact, seen that they only differ 
 from each other in external form, and that these forms 
 are very variable, since the same organism may present 
 itself successively as an isolated globule, a chaplet, a 
 chain, and a more or less articulated rod. Microbes are 
 essentially polymorphous, and adapt themselves to 
 varied conditions of existence, which influence the 
 form taken by these microscopic organisms. For this 
 reason their classification has often varied, their dis- 
 tinction into genera and species does not yet rely on 
 precise data, and the opinions formed by various 
 authors in accordance with their personal researches 
 still differ widely. 
 
 We will, however, subjoin Wunsche's classification. 
 
 Schizophyta, or Schizomycetes. 
 
 A. Division of cells alwaj's occurring in the same direc- 
 tion, so as to form a chaplet before the joints 
 or members separate. 
 
 1. Cells united in mucilaginous or gelatinous families. 
 a. Cells united (in a state of repose) in nmorphoue 
 
 families. 
 
 a. Spherical or elliptic cells, colourless and gene- 
 rally motionless Micrococcm. 
 
 0. Cells elongated in short, movable rods ... Bacterium. 
 
 6. Cells united in families with sharp outlines, lobu- 
 
 lated and agglutinated like frog-spawn ... Ascococcus* 
 
 2. Cells arranged in filaments. 
 
92 MICROBES, FERMENTS, AND MOULDS. 
 
 a. Cylindrical filaments, indistinctly articulated, mo- 
 
 tionless. 
 a. Unramified, very slender filaments: 
 
 (1) Short .................. Bacillus. 
 
 (2) Long ...... ............ Leptotkrix. 
 
 ft. Filaments repeatedly bifurcated (false ramiii- 
 
 cations) ............... Cladothrix 
 
 b. Spiral, movable filaments: 
 
 (1) Short, faintly undulated ......... Sjriroclicete. 
 
 (2) Long, flexible ............... Vibrio. 
 
 (3) Short, rigid ............... Spirillum. 
 
 (4) Rolled into mucilaginous mass ...... Myconostoc 
 
 B Cells dividing cross-wise, and the daughter cells re- 
 
 maining united, like packets tied with a crossed 
 
 cord .................. Sardna. 
 
 Most of the microbes of which we have now to speak 
 may be assigned to one or other of the genera given in 
 this scientific enumeration, and sometimes, on account 
 of their polymorphism, to several of these genera. 
 
 Before making a more detailed study of some of 
 them, it may be interesting to glance at them as a 
 whole, following the order of classification given above. 
 
 The genus Micrococcus (Hallier) includes the 
 spherical microbes, which are the most common and 
 the most widely diffused, probably because the spores 
 
 ^ and early stages of all the other forms 
 
 V*V^* have this spherical shape before be- 
 
 * /!>" coming elongated and assuming their 
 
 "T ^fr O O O O 
 
 . ; * adult form (Fig. 50). 
 
 F*. 50. -Microbes Tm ' S g 6I1US ls Divided into two 
 
 sections: the first includes Micro- 
 
 coccus chromogenis, i.e. fabricators of 
 colouring matter an extremely interesting group, on 
 
MICROBES, OR BACTERIA. 93 
 
 which we must say a few words, since these microbes 
 play an important part in nature, connected with 
 hygiene and domestic economy ; the second section 
 includes Micrococcus pathogenis, or the producers of 
 disease, which must detain us longer. 
 
 The genus Bacterium, of which the name indicates 
 that it is rod-shaped, also includes some coloured 
 species and more which are colourless, such as the 
 bacteria of putrefaction, of stagnant waters, of vegetable 
 infusions, etc. (Fig. 49). 
 
 The genus Ascococcus is less common. The cells, 
 united in groups or families, form mucilaginous, 
 wrinkled membranes on the surface of putrefying 
 liquids, on the juice of meat, on the infusion of 
 hay, etc. 
 
 Bacillus (or Bacteridice, Davaine) forms an ex- 
 tremely important genus, characterized by its long, 
 flexible, and articulated filaments ; this genus includes 
 the butyric ferment, and the microbe which produces 
 the disease called anthrax, or splenic fever. 
 
 Leptothrix buccalis is found in the human saliva 
 and between the teeth (Fig. 51, k). 
 
 Cladothrix dichotoma forms a kind of fine grass, 
 which appears like a whitish mucilage on the surface 
 of putrefying liquids (Fig. 51, p). 
 
 Vihrio rugula and V. serpens are found in 
 infusions in the form of tolerably thick filaments, 
 which have only one inflection, while their successors 
 are spirally curved (Fig. 51, I). 
 
94 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 Spirillum and SpirocJwete only differ from each 
 other in the number and approximation of their 
 spirals. Spirochoete Obermeieri is found in the blood 
 of those affected by recurrent fever; 8. plicatile, 
 which is found in stagnant water, arnid Oscillaria, is 
 
 Fig. 51. Different forms of microbes, or bicteria: a, 6, c, d, Hicrococms of various 
 forms ; e, the short Bacterium ; f, the short Bacillus ; k, Js-ptotkrix or long 
 bacillus: I, Vibiio, dividing by fission; m, Spirillum; o, Spirochwte ; p, Clado- 
 thrix, etc. (from Zopf : highly magnified). 
 
 perhaps only the parasitic form of those algfe, and 
 has often been regarded as the cause of marsh fever. 
 Spirillum is also found in infusions (Fig. 51, m, o). 
 
 Finally, Sarcina ventriculi, so different in form 
 from other microbes, is found in the fluids of the 
 human stomach, in the blood, and in the lungs, in the 
 
MICROBES, OR BACTERIA. 95 
 
 form of yellow patches. It is also found in the albu- 
 men of boiled eggs, in potatoes, etc. (Fig. 52). 
 
 52. Sarcina ventriculi, in different degrees of development 
 (strongly magnified). 
 
 III. THE MICROBE OF VINEGAR, AND ACETIC 
 FERMENTATION. 
 
 Pasteur has shown that the acid fermentation of 
 alcoholic liquids is due to the existence of a special 
 microbe, acting like a ferment, which is. developed on 
 the surface of fermented liquors whenever they are 
 abandoned to the contact of the air, in the presence of 
 albuminoid substances. This microbe, which consti- 
 tutes the mother of vinegar, and which is termed 
 Mycoderma aceti, is probably identical with Bacterium 
 lineola, so often present in infusions, in stagnant 
 pools, and even in spring water. It is a true 
 bacterium (Fig. 48). 
 
 The membrane which may be observed on the 
 surface of liquids in course of acetic fermentation is 
 formed of very minute elongated cells, from 1'5 to 3 
 micro-millimetres in length, united in the form of 
 
96 MICROBES, FERMENTS, AND MOULDS. 
 
 chains or curved rods. They multiply by the trans- 
 verse fission of the cell, a fission preceded by a median 
 constriction. These are characteristics of the bac- 
 terium, strictly so called. 
 
 The nutrition of this microbe resembles that of 
 beer-yeast : it requires mineral salts, phosphates of the 
 alkaline metals and of the metals of the alkaline 
 earths, proteid matters, or ammoniacal salts. 
 
 This ferment is an oxidizing ferment, which with- 
 draws oxygen from the air and transfers it to the 
 alcohol, thus converting it into acetic acid ; hence it 
 can only subsist in contact with the air, and perishes 
 when it is submerged, so that acetification is then 
 arrested. The oxidizing power of this microbe is 
 such that it can even oxidize alcohol and transform it 
 into carbonic acid gas a fact which explains how the 
 strength of wine is lowered by the other and larger 
 species, Mycoderma vini, of which we have given an 
 illustration (Figs. 43, 44). This action is less lively 
 in the presence of a considerable quantity of vinegar, 
 and at Orleans acetification is always effected in vats 
 which contain a large amount. 
 
 What is called the Orleans process, which is the 
 one generally employed in France, consists in filling 
 tuns which can hold about 200 litres with 100 litres 
 of vinegar and 10 litres of white or red wine ; once a 
 week 10 litres of vinegar are drawn off, and replaced 
 by 10 litres of wine. The temperature should be 
 about 30. Oxygen is supplied by a proper system of 
 
MICROBES, OR BACTERIA. 97 
 
 ventilation. This process is somewhat slow, since it 
 only produces ten litres of vinegar out of each tun in 
 the course of the week, and it has the disadvantage 
 of encouraging the multiplication of anguillidce , the 
 small nematoid worms which live in vinegar and sour 
 paste. 
 
 Pasteur has modified and improved the original 
 process so as to obviate both inconveniences. He 
 employs heat, which allows the process of acetification 
 to be intermittent, and thus prevents the development 
 of the anguillidce. Shallow vats, about 30 centi- 
 metres in depth, with lids in which holes ha^e been 
 pierced, are used, and mycoderma is scattered on their 
 surface. Gutta-percha tubes, pierced with holes at 
 their lower extremity, are placed at the bottom of 
 these vats, so that fresh liquid can be added without 
 disturbing the superficial film of mycoderma. 
 
 In Germany, vinegar is made by means of spongy 
 platinum, or platinum black, which oxidizes alcohol 
 without the intervention of a microbe. This affords 
 a good example of fermentation, or of an analogous 
 phenomenon, produced solely by physico-chemical 
 action. The platinum black acts by disintegrating 
 the alcohol and placing it in more intimate contact 
 with the oxgyen of the air, since the process of 
 oxidation would be much slower without either this 
 process or the presence of the ferment. 
 
98 MICROBES, FERMENTS, AND MOULDS. 
 
 IV. TIIE MICROBES WHICH AFFECT WINE. 
 
 The affections to which some wines are subject 
 alter their taste and quality so as often to render 
 them unfit for use. These affections ought to be 
 recognized, so that a diseased wine may not be con- 
 founded with one which is adulterated, and it is by 
 means of the microscope that we are enabled to 
 recognize the nature of these changes. Chaptal for- 
 merly ascribed them to the presence of an excess of 
 ferment, since he was unable to discover any other 
 cause. We now know from Pasteur's valuable re- 
 searches, published in his book, Etudes sur Ics vins, 
 that they are all due to the. presence of microbes 
 peculiar to each disease. 
 
 " The source of the diseases which affect wine," 
 Pasteur writes, " consists in the presence of parasitic 
 microscopic plants, which are found in wine under 
 conditions favourable to its development, and which 
 change its nature either by the withdrawal of what 
 they take for their own nutriment, or still more by 
 the formation of fresh products which are due to the 
 multiplication of these parasites in the wine." These 
 diseases are known under the names of acescence, 
 pousse, graisse, amertume, etc. We shall review them 
 in succession. 
 
 Mouldy or Flowered Wine. These are wines on the 
 surface of which white pellicles are formed (jieurs de 
 viri), which consist of Mycoderma vini (Figs 43 53). 
 
MICROBES, OR 
 
 99 
 
 This product does not turn the wine sour, nor sensibly 
 affect it. It is due to the temperature of the casks N ; 
 being too high during the hot season. It may be 
 obviated by sprinkling them with cold water, or by^_ 
 putting ice into them; care must also be taken to 
 keep the casks full, and the cellars as cool as possible. 
 Acidity of Wines; Soured Wines. Wine always 
 
 Fig. 53. The disease acescence, which sours wine. Deposit seen in the n icroscope; 
 1,1, Mi/coderma vini; 2, 2, Mticodfrma aceti, still young ; 3, the same older, when 
 the mischief is at an advanced stage. 
 
 contains a small quantity of acetic acid, and when 
 this acid is in exdess, the wine is no longer drinkable, 
 and turns to vinegar. This change is due to the 
 presence of Mycoderma aceti (Fig. 53), of which we 
 have already spoken. It is much more minute than 
 M. vini, and takes the form of the figure 8, as the 
 illustration shows, or of chaplets formed by the union 
 
100 MICROBES, FERMENTS, AND MOULDS. 
 
 of several 8's placed end to end. As they grow older, 
 the two globules of the 8 divide, and appear as isolated 
 granules. These two species of Mycoderma are in- 
 compatible, and are never found in the same wine, 
 
 The acid may be isolated by distilling the sour 
 wine. The attempt has been made to cure or im- 
 prove sour wine by adding normal potassium tartrate 
 (from 200 to 400 grammes to every hogshead of 230 
 litres), which forms potassium acetate and bi tartrate 
 by neutralizing the excess of acid. The bitartrate is 
 deposited spontaneously, and Crystal lizes. Carbonate 
 of lime cannot be employed for the same purpose, 
 since it would spoil the wine. 
 
 Wines that are turned or over-fermented (vins 
 pousses ; vins bleus). This disease displays the follow- 
 ing characters : the wine assumes a bluish or brown 
 
 o 
 
 colour, and becomes turbid ; if shaken in a test-tube, 
 we may observe silky waves floating in every 
 direction. When a cask is tapped, the wine spurts 
 up, and it is said "quit a la pousse" If poured 
 into a glass, a number of minute bubbles appear on 
 the surface, the discolouration increases, and the wine 
 becomes more turbid. The taste is changed and 
 becomes insipid, as if water had been added. The 
 disease is developed in very hot weather (Chevalier 
 and Baudrimont). 
 
 This affection is due to the presence of an ex- 
 tremely attenuated microbe, somewhat resembling 
 that of lactic acid, which we shall describe presently, 
 
MICROBES, OR BACTERIA. 
 
 101 
 
 but differing from the latter in its undivided filaments. 
 Its diameter is at the most one micro-millimetre : it 
 varies in length, and is flexible, in which it resembles 
 the genus Vibrio. These filaments collect in a 
 mucous deposit at the bottom of the cask (Fig. 54). 
 
 Wine undergoes successive changes under the in- 
 fluence of this pathogenic ferment, and this has led 
 
 Fig. 54. Wines affected by pousse. Deposit seen under the microscope: 1, ordinary 
 alcoholic wine-ferment ; 2, acicular crystals of potassium bitiirtrate ; 3, crystals 
 of normal calcium tartrute ; 4, Vibrio, or microbe which produces the disease. 
 
 to the belief that there are several distinct diseases; 
 hence the different names which have been given to 
 this affection. 
 
 The remedies for the disease consist in the ad- 
 dition of tartaric acid ; in drawing off the wine into 
 sulphured* casks, and adding a little brandy ; and in 
 taking care to keep the cellars whitewashed and airy. 
 
102 MICRODES, FERMENTS, AND MOULDS. 
 
 Wine affected by Ropiness. White wines, and 
 especially champagne, are more often affected by this 
 disease than red wines. It is more apt to attack wine 
 which has little alcohol and is deficient in tannin, 
 and under its influence the liquor becomes turbid, flat, 
 and insipid, ropy, like white of egg, and it loses its 
 sugar. 
 
 This change is effected by a filamentous microbe, 
 
 Fig. 55. Disease of ropiness in wine, affecting champagne, nn<1 caused by a bacterium 
 which assumes two forms : the figure 8, and chaplets. 
 
 even more like the lactic ferment (Fig. 58) than the 
 one we have just described, since it is likewise formed 
 of very minute globules, united in chaplets, which 
 are, however, more attenuated than those of the lactic 
 ferment. These filaments form a species of feltwork 
 through which the liquid slowly filters; hence its 
 oily appearance. It is probably a bacterium (Fig. 55). 
 
Mi^ROBES, OR BACTERIA. 103 
 
 This ferment ma^^^destroyed by tannin (15 
 grammes to a hogshead), ^^||hhas the effect of pre- 
 cipitating it. Very ripe sorbs, wmN^have been crushed, 
 may also be used for this purpose, as well as gall- 
 nuts and grape-seeds which have been ground to 
 powder ; all substances rich in tannin. The precipitate 
 thus formed should be separated from the wine by 
 refining. 
 
 Wines affected by Bitterness. This disease affects 
 red wines, especially those of the choicest vintages 
 of Burgundy. Pasteur writes that "at its outset 
 the wine assumes a peculiar smell, its colour is less 
 vivid, and its taste becomes insipid. Soon the wine 
 becomes bitter, and there is a slight taste of fermen- 
 tation, due to the presence of carbonic acid gas. 
 Finally, the disease becomes more aggravated, the 
 colouring matter is completely changed, and the wine 
 is no longer drinkable." 
 
 The microbe which is the essential cause of this 
 disease is seen under the microscope in the form of 
 articulated filaments, curled back or bent, and it may, 
 or may not, be invested with the colouring matter of 
 the wine. It is reproduced by fission, not by bud- 
 ding. It is probably a bacillus (Fig. 56). 
 
 This ferment must not be confounded with that 
 of wine affected by pousse, of which the filaments are 
 much more slender, the articulations are hardly apparent, 
 and they are not incrusted with colouring matter. 
 Pousse is readily developed in wines of inferior quality, 
 
104 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 while the finer sorts are more often attacked l>y 
 bitterness. 
 
 The bitterness may be to some extent neutralized 
 by the addition of new and sweet wines, but the 
 application of lime (from 25 to 50 centigrammes the 
 
 Fig 56. Bitter disease of wine. Deposit under the microscope : 1, 2, filaments of the 
 microbe (Bacillus') which produces the disease, mixed with crystals of tartar and 
 colouring matter (Bordeaux wine) ; 3, young microbes in an active state ; 4, dead 
 microbes, incrusted with colouring matter. 
 
 litre) is more recommended. This treatment most, 
 however, make the wine sour. 
 
 The deposits formed in deteriorating or old wines 
 are not effected by the microbes which we have just 
 enumerated, but are due, according to Pasteur, to 
 the combination of oxygen with the wine under the 
 action of time. This constitutes the aging of wine. 
 
 Viscous Fermentation of Saccharine Liquids. 
 What is termed viscous fermentation takes place in the 
 
MICROBES, OR BACTERIA. 105 
 
 juice of beetroots, carrots, and onions, and in liquids 
 containing sugar and nitrogenous substances. It is 
 probably produced by the same ferment which causes 
 the ropiness of wine (Fig. 55), and the liquid assumes 
 a viscous or oily appearance. 
 
 Pasteur states that this microbe acts on the glucose 
 and transforms it into gum or dextrine, into mannite 
 and carbonic acid. The lactic and butyric fermenta- 
 tions, which are often simultaneously produced in 
 saccharine liquids, are due to distinct microbes. 
 
 V. THE MICROBE OF LACTIC FERMENTATION. 
 
 The sugar contained in milk, as well as grape 
 sugar, can be transformed into lactic acid. This 
 transformation is always caused by the presence of 
 a ferment with which Pasteur has made us ac- 
 quainted. It had been previously supposed that milk 
 turned sour spontaneously when it was allowed to 
 stand for some days. In this case, as we know, the 
 milk curdles, and the clear liquid which separates 
 from the curd is called whey. In 1780, Scheele, the 
 celebrated Swedish chemist, extracted lactic acid from 
 whey. The same acid is also found in sour-crout; 
 in the sour water of starch ; in baker's yeast ; in water 
 in which peas, beans, or rice have been boiled, and then 
 suffered to ferment; and, finally, in the juice of beet- 
 root which has passed through viscous and alcoholic 
 
106 MICROBES, FERMENTS, AND MOULDS. 
 
 fermentation, after which it turns sour and produces 
 lactic acid and mannite. 
 
 Lactic fermentation requires the presence of pro- 
 teid matters in process of decomposition, and it can 
 only be carried on when the degree of acidity in the 
 liquid does not exceed definite limits. For this purpose 
 a certain amount of chalk is added, to neutralize the 
 acid formed at the expense of the sugar. 
 
 It is somewhat difficult to observe the microbe of 
 this fermentation without previous instruction. It 
 appears in the form of grey patches, which are readily 
 confounded with casein, and with the disintegrated 
 gluten, or the chalk of the liquid under examination. 
 
 \ 
 
 Fig. 57. Lactic ferment in a Fig. 58. Lactic ferment 
 
 cbciplet (^ciiut/.e..berger). (Pasteur). 
 
 Under the microscope the patch is seen to consist of 
 minute globules, or of filaments with very short articu- 
 lations, isolated or in flakes. These are the characters 
 of the genus Bacterium (Figs. 57, 58). The globules 
 are much more minute than those of the yeast of beer, 
 and are strongly agitated when in isolation by a 
 motion incorrectly termed Brownian movement, and 
 which does not in reality differ from the movements 
 which may be observed in most of the spores of the 
 lower orders of plants, and in a great number of 
 bacteria. 
 
MICROBES, OK BACTERIA 107 
 
 This ferment is often found in wine, together with 
 those of yeast and alcohol, and produces in it an in- 
 cipient lactic fermentation. The predominance of one 
 of these fermentations depends on the composition 
 of the medium, which may be more or less adapted 
 to them. A slightly alkaline medium is most suitable 
 for the lactic microbe, while in a perfectly neutral 
 medium only alcoholic fermentation will occur. 
 
 We have already said that mare's milk can be 
 transformed into an alcoholic liquid called koumiss. 
 
 VI. THE AMMONIACAL FERMENTATION OF URINE. 
 
 Shortly after its discharge, urine which is left to 
 itself assumes an ammoniacal odour. This is due 
 to the transformation of the urea (the nitrogenous 
 principle of urine) into ammonia -and carbonic acid, 
 under the influence of a microbe which appears in 
 the form of free globules, of articulated filaments 
 (Torulci), or of chaplets, resembling those of the lactic 
 ferment. This microbe is found in the white deposit 
 which collects at the bottom of vessels, and has been 
 termed Micrococcus urese (Fig. 59). 
 
 This ferment is conveyed through the air, like 
 other microbes of fermentation. It does not exist in 
 the bladder as long as the urine remains acid. Yet, 
 in the rare cases in which urine has been found to be 
 alkaline, immediately after its issae from the bladder, 
 
108 MICROBES, FERMENTS, AND MOULDS. 
 
 it may be ascertained that the ferment was introduced 
 by some accidental cause, such as a surgical examina- 
 tion, and that the sound served to convey the microbe. 
 It is, in any case, sufficiently common at the exterior 
 orifice of the urethra, and at the depth of two or three 
 centimetres. 
 
 Von Tieghem has shown by precise experiments 
 
 K!g. 59. Micrococcus urea (Von Tieghem). Microbe of ammoniacal fermenfatfon. 
 Jt may be observed that the bacterium is in the figure 8, or in chaplets. (Much 
 magnified.) 
 
 that the presence of this microbe is the true cause of 
 the ammoniacal fermentation of urine. With certain 
 precautions, the urine withdrawn from a healthy 
 bladder may be preserved for an indefinite time. 
 
 These experiments have been recently resumed by 
 Sternberg, an American physician, who has clearly 
 demonstrated that only the microbes of the air, or 
 
MICROBES, OR BACTERIA. 109 
 
 those of the orifice of the urethra, can produce this 
 fermentation. Since the latter are always carried off 
 by the first discharge of urine, only the second por- 
 tions of the emitted liquid should be collected in 
 a perfectly clear vessel, which has been sterilized, 
 or, carefully freed from all atmospheric germs. The 
 vessel should then be put under a glass shade to 
 protect it from these germs, and if all proper pre- 
 cautions are taken, the urine will remain clear and 
 acid for an indefinite time without undergoing am- 
 moniacal fermentation. If afterwards a little plug 
 of amianthus, which has been previously sterilized 
 by heat, should be introduced by a small pair of 
 pincers into the urethra to a depth of two centi- 
 metres, and then dropped into this untransformed 
 urine, it will soon be transformed, and undergo arn- 
 moniacal fermentation. But if the plug of amianthus 
 has been steeped in an antiseptic solution (diluted 
 carbolic acid) before being introduced into the urethra, 
 it will not produce this fermentation. 
 
 VII. BUTYRIC FERMENTATION OF BUTTER, CHEESE, 
 AND MILK. 
 
 Butyric fermentation follows lactic fermentation in 
 milk, butter, and cheese, and it is butyric acid which 
 gives to butter its rancid taste. This fermentation 
 also occurs in saccharine substances, and generally 
 in all proteid substances. 
 
110 MICROBES, FERMENTS, AND MOULDS. 
 
 Pasteur has ascertained that this fermentation 
 results from the development of a microbe which 
 takes the form of minute cylindrical rods, rounded at 
 their extremities, usually straight, and either isolated 
 or united in chains of two or more articulations. 
 These rods are about two micro-millimetres in width, 
 and from two to twenty micro-millimetres in length. 
 They advance with a gliding motion, are often curved, 
 and present slight undulations. They are reproduced 
 by fission. These characters are those of the genus 
 bacillus. 
 
 Coagulation of Milk: Cheese. The coagulation of 
 milk is artifi ially produced by rennet, the liquid 
 secreted in a calf's stomach. Human gastric juice 
 produces the same effect, and the milk introduced as 
 an aliment into the stomach is never digested until it 
 has been curdled, both in children and adults. The 
 artichoke flower, and other plants of the genus Car- 
 duus, will also curdle milk at a temperature between 
 30 and 50. It is probable that this 
 action is due to the presence of an 
 organized ferment (animal or vege- 
 . 6o.-i?aciHws amy- table cells), which here supplies the 
 cus\ butymi lermfut place of the microbe of lactic fernien- 
 
 agent in the fabrica- 
 tion of cheese, tation. 
 
 It is with rennet, or with the still more active 
 liquid produced by the maceration of the testicle of an 
 un weaned calf, that those cheeses are made which 
 consist only of curd, boiled or unboiled, fresh or fer- 
 
MICUOBKS, OK BACTERIA. Ill 
 
 merited, and obtained from the milk of cows, sheep, 
 or goats, skimmed or unskimmed, according to the 
 kind of cheese desired. 
 
 Sweet-milk cheese do not differ in their composi- 
 tion from those of curdled milk. They consist of casein, 
 albuminoid matter which encloses particles of butter : 
 the liquid residue is the serum or whey, which con- 
 tains lactic acid and mineral salts. 
 
 Cheese, strictly so called, such as Gruyere and 
 Roquefort, only differ from the foregoing because they 
 have been exposed for a shorter or longer time to the 
 action of the air, and of the microbes suspended in it. 
 Cheese is first oxidized under the influence of the 
 vxygen of the air ; butyric and even alcoholic fermen- 
 tation soon follows lactic fermentation, together with 
 the disengagement of hydrogen and of putrid pro- 
 ducts, when the action of the ferments which effect 
 these transformations has gone on too long. 
 
 In order to obtain the different kinds of cheese 
 which come into the market, they are exposed to the 
 weather, generally in holes which have been excavated 
 in the rock for this purpose, on a bed of straw, or 
 sometimes partially covered with it, until the cheese 
 is ripe and has attained the desired quality. 
 
 Butyric and ammoniacal fermentations lead us 
 directly to the study of putrefaction ; that is, the fer- 
 mentation of dead organic matter. 
 
112 MICROBES, FERMENTS, AND MOULDS. 
 
 VIII. PUTREFACTION, OR THE FERMENTATION OF 
 DEAD ORGANIC MATTER; A GAME FLAVOUR. 
 
 The flesh of animals used for food is said to be 
 high in the first stage of alteration which occurs when 
 it is left to itself. Pasteur does not believe that this 
 effect is produced by the intervention of the ferments 
 of the air, although this is the case with the putrefac- 
 tion which follows. He thinks that it merely results 
 from the action of what are called soluble or natural 
 ferments in the serum of the meat, and that there is 
 a chemical, reciprocal reaction of the liquids and solids 
 which are withdrawn from the normal action of vital 
 nutrition. This explanation is adapted to satisfy those 
 epicures who have a taste for high game and not for 
 microbes. Yet it is certain that this condition passes 
 into true putrefaction without any abrupt transition, 
 and we know that immediately after death the microbes, 
 which penetrate everywhere, take possession of the 
 animal tissues and begin their work of destruction. 
 When flesh is high, it is therefore probable that it 
 is in the first stage of putrefaction. 
 
 Gautier has made some experiments on the sub- 
 ject, and holds that this condition is certainly due 
 to the action of microbes, and consequently to germs 
 in the air. In fact, meat which is placed in a soldered 
 and air-tight case after it has been deprived of germs 
 by a suitable process, is devoid of any high odour at 
 
MICROBES, OR BACTERIA 4 113 
 
 the end of six months, and is as fit for food as freshly 
 killed meat. 
 
 However this may be, meat which is high is 
 usually not injurious, while putrefied meat produces 
 diarrhoea or still more serious illness. Davaine has 
 shown that the septic properties of decomposed blood 
 are not removed by subjecting it to a temperature 
 of 100, which destroys the microbes, but not their 
 germs or spores; for the destruction of the latter a 
 still higher temperature is necessary. 
 
 For a long while it was believed that the putrefac- 
 tion of dead bodies, and of albuminoid substances, 
 either animal or vegetable, which have been exposed 
 to a moist air at a temperature of from 1 5 to 30, was 
 merely due to the instability of the organic compounds; 
 these, when left to themselves, tend, under the influence 
 of oxygen, to produce more stable compounds by dis- 
 integration and successive oxidations. Pasteur has, 
 however, shown that in this case also there is a true 
 fermentation; that is, a decomposition produced by 
 the vital action of certain microbes. 
 
 In general, when organic animal substances are 
 exposed to the air, they are in the first instance 
 rapidly covered with moulds ; they lose their co- 
 herence, and after the lapse of a few days give off 
 fetid effluvia. Carbonic acid, nitrogen, hydrogen, 
 carburetted, sulphuretted, and phosphoretted hydro- 
 gens, are freely disengaged, and at the same time they 
 combine with the oxygen of the air. The microbes, 
 
114 MICKOBIiS, FERMENTS, AND MOULDS. 
 
 which appear simultaneously with the moulds, pene- 
 trate deeply into the tissues, disintegrate them by 
 feeding at their expense, and the putrid condition 
 increases ; then the decomposition changes its nature 
 and becomes less intense. The putrefied matter is 
 finally desiccated, and leaves a brown mass a complex 
 mixture of substances combined with water (hydro- 
 carbons), and of fatty and mineral substances which 
 gradually disappear by slow oxidation (Gautier). 
 
 Pasteur has ascertained, from the microscopic 
 
 Fig. 61. Bacilli of pu- 
 i refaction (Rosenbach : 
 mi.ch magnified) Fig. 62,Zoogloea of Spirillum tenue. 
 
 study of the phenomena which occur in an infusion 
 of animal matter in process of decomposition, that 
 microbes appear in it in the form of globules or 
 short rods (Micrococcus, Bacterium termo, Bacillus, 
 etc.), which are either . free or collected in a semi- 
 mucilaginous mass, to which the special name zoogloea 
 was at first given (Fig. 62). These microbes rapidly 
 deprive the liquid of all its oxygen. At the same 
 time a thin layer of mucedinece and of bacteria is 
 
MICROBES, OK BACTERIA. 115 
 
 found on the surface, which also absorb this gas and 
 do not allow it to penetrate into the lower part of 
 the liquid. 
 
 This liquid now becomes the seat of two very 
 distinct actions. In its interior, vibriones succeed to 
 the free globules and zoogloea, of which they appear 
 to be only a higher stage of transformation. These 
 microbes multiply and change the albuminoid matter 
 into more simple substances ; insoluble cellulose, fatty 
 bodies, and gaseous putrid matters. Meanwhile, the 
 microbes on the surface actively consume the products 
 thus developed, transforming them into carbonic acid, 
 nitrogen, and the oxides of nitrogen, etc. This ex- 
 plains why, when there is an insufficiency of oxygen, 
 putrefaction may indeed begin ; but it languishes, and 
 is finally arrested. 
 
 The cause of the fetid odours which escape from 
 putrefying bodies and liquids is not well understood. 
 It may be ascribed to the disengaged gases (carburetted, 
 phosphoretted and sulphuretted hydrogen, and ammo- 
 niacal compounds), and to the circulation of decom- 
 posing organic particles. We also find formic, acetic, 
 lactic, butyric, valerianic, and caproi'c acids, generally 
 combined with ammonia, and the fatty acids which 
 are one result of the successive disintegrations of 
 albuminoid matters. 
 
 When these gases are disengaged, a substance 
 remains which may be compared with humus, or 
 vegetable earth. It is rich in fats, in earthy and 
 
116 MICROBES, FERMENTS, AND MOULDS. 
 
 ammoniacal salts, and consequently constitutes a 
 strong manure, very fit to serve as the nutriment of 
 plants. 
 
 This is at once the beginning and the termination 
 of the endless chain which sustains the equilibrium 
 of nature, in which there is no creation, no destruction. 
 Plants draw their nutriment from the soil and the air 
 in the form of mineral solutions, and are devoured 
 by animals or by other parasites ; animals are in their 
 turn devoured by microscopic plants or microbes, and 
 return by means of putrefaction to the condition of 
 mineral salts, which are distributed in the soil, and 
 serve anew for the nutrition of plants. 
 
 We must at the same time be struck by the 
 resemblance which exists between these phenomena 
 of putrid fermentation, and those which occur in the 
 fermentations which accompany the nutrition of 
 animals and plants. Germination and the different 
 digestions which occur in the mouth, the stomach, 
 the intestines, etc., are only fermentations, so that 
 Mitscherlich has paraphrased the Scripture saying, 
 " Dust thou art, and unto dust thou shalt return," 
 by declaring that " Life is only a corruption." 
 
 It should, however, be remembered that fermenta- 
 tions are essentially phenomena of disintegration, 
 which always reduce complex, organic substances to 
 those which are simpler. Plants provided with 
 chlorophyl, on the other hand, alone possess the 
 property of forming higher organic compounds, by 
 
MICROBES, OR BACTERIA. 117 
 
 the aid of purely inorganic substances. Animals and 
 plants devoid of chlorophyl get their nutriment by 
 unmaking the complex substances elaborated by the 
 green parts of plants, and these act in the same way 
 for their own profit in those organs which have no 
 chlorophyl ; as, for instance, in the seed and embryo. 
 
 IX. AEROBIES AND ANAEROBIES. 
 
 We have seen that microbes, at different epochs 
 of their existence, and in accordance with the nature 
 of their environment, can assume very diverse forms. 
 Thus the organism, which at first appears in the form 
 of globules (micrococcua), either isolated or united in 
 more or less numerous colonies by a kind of muci- 
 laginous envelope (Zooc/lova), when it again becomes 
 free, may be elongated in the shape of the figure 8, 
 which is formed of two cells about to separate; or 
 a large number may be included in the form of a 
 straight, articulated rod (Bacterium), or in a rod 
 which is curved, waved, or even spiral (Vibrio, 
 Spirillum, Spiroch&te), always more or less mobile; 
 or, again, the cells may form long, stationary filaments 
 (Bacillus), etc. 
 
 So also the habitat and mode of life divide the 
 microbes into very distinct classes. Some can only 
 subsist when they breathe the natural oxygen they 
 withdraw from the atmosphere; they can only exist 
 
118 MICROBES, FERMENTS, AND MOULDS 
 
 on the surface of liquids, or of the organic substances 
 on which they feed. These are termed aerobics, 
 or consumers of air. Others, again, can live beneath 
 the surface of liquids and in living organisms, or of 
 those in process of decomposition, and must neces- 
 sarily derive the oxygen necessary for their respira- 
 tion from the oxygenated substances in which they 
 are found. These are termed anaerobies. 
 
 p n 
 
 Fig. 63. Vibrio rugula in different stagss of development ^anaerobie), much enlarged. 
 
 This distinction and the theory on which it relies 
 have been introduced into science by Pasteur, and 
 they appear to be founded on observed facts. Thus 
 Bacterium termo, which lives on the surface of putre- 
 fying liquids, is an aerobie ; while Vibrio rugula 
 (Fig. 63), which lives below the surface of the liquid, 
 below the layer formed by the Bacterium termo, is an 
 anaerobie, and derives its oxygen from the water or 
 solid matters which are found in it in suspension or 
 solution, and even from other microbes. So, again, 
 the yeast of superior beer is an aerolde, and the yeast 
 of inferior beer is an anaerobie, etc. Paul Bert regards 
 
MICROBES, OR BACTERIA. 119 
 
 the corpuscles of the blood, and the cells of which all 
 our tissues consist, as true anaerobic microbes ; so 
 likewise are the microbes which, when introduced into 
 the blood, are the cause of certain diseases. The 
 important consequences of this fact, which it is neces- 
 sary to note, will appear presently. 
 
 X. THE MICROBES OF SULPHUROUS WATERS. 
 
 The formation of the sulphurous springs which 
 are so numerous in the Pyrenees and in other parts 
 of France, appears to be due to the presence of small 
 algse of the family Oscil- 
 latoria, and of the genera 
 Oscillaria and Beggiatoa 
 (Fig. 64). These microbes 
 are of the same structure 
 
 Fig. <M. Beggiatoa alba, microbe of 
 
 as those of which we have suipuu.ous springs. 
 
 spoken above, but they contain chlorophyl, and also 
 a blue colouring matter. They are placed in the 
 group Cyanophycew, which, as Zopf believes, contains 
 species that are sometimes green, and sometimes 
 colourless, like Bacillus and Leptothrix, which they 
 resemble in their mode of reproduction. 
 
 According to Louis Ollivier, these algye reduce the 
 sulphates of waters charged with sulphate of lime, 
 transforming them into sulphur. They even accumu- 
 late sulphur in their cells. When sulphur is thus 
 
120 MICROBES, FERMENTS, AND MOULDS. 
 
 abundantly supplied to them, the microbes are very 
 mobile ; as soon as the quantity of sulphur diminishes 
 they become less mobile, and reconsume the sulphur 
 they have stored up ; finally, they become quite 
 motionless a phenomenon concomitant with the forma- 
 tion of spores. Within each cell of the filamentous 
 alga there is a minute sphere, brilliant and refracting, 
 of which the development is in inverse ratio to the 
 quantity of sulphur in the surrounding liquid, These 
 spores become free in the form of chaplets, after the 
 destruction of the cell-wall, and these chaplets are 
 precisely like those of Bacillus subtilis. 
 
 Planchud was the first to whom it occurred to 
 look for a special ferment in the glairine or baregine 
 w r hich may be seen floating on the surface of sul- 
 phurous waters. He showed that one gramme of car- 
 bolic acid to a litre of water arrests the reduction of 
 the sulphates into sulphur, and that this reduction is 
 resumed as soon as the carbolic acid has evaporated. 
 Six grammes to the litre completely destroy the 
 Sulphuraria, as these algse are termed by Planchud. 
 
 This observer also performed experiments which 
 led him to believe that the same algae will reduce 
 gypsum to native sulphur, and that the vast deposits 
 of sulphur found in certain regions are due to the 
 action of this microscopic plant. It is now well 
 known that a chemical action of the same nature, 
 the production of saltpetre, is the work of similar 
 microbes. 
 
MICROBES, OR BACTERIA. 121 
 
 XL THE MICROBES WHICH PRODUCE SALTPETRE. 
 
 It is known that nitre or saltpetre, i.e. potas- 
 sium nitrate, is produced in damp places where de- 
 composing animal matter is found in contact with 
 carbonate of potassium. It is found, combined with 
 other salts of lime, soda and magnesia, in stables, sheep- 
 folds, cellars, in the neighbourhood of urinals, and 
 in the earth of some localities (Peru and Chili). Its 
 industrial importance in the manufacture of gun- 
 powder, etc., has led to its collection. Formerly it 
 was extracted from the plaster of old houses, or from 
 artificial nitre w r orks which combined conditions 
 favourable to its production. Nitrates are produced 
 by the gradual oxidation of the ammonia furnished 
 by animal excretions. For a long while ifc was supposed 
 that this oxidation was simply due to the influence 
 of porous bodies, such as earth and stone walls. Nitric 
 acid was produced, then nitrates of lime, potas- 
 sium, etc. 
 
 The researches of Boussingault, Schloesing, and 
 others, have now taught us that this phenomenon of 
 organic chemistry is due, like many others, to the 
 vital activity of one or more species of microbe, 
 whose invariable presence in the natural or artificial 
 nitre-works has been ascertained. These microbes are 
 aerobies, i.e. they only live and work when in contact 
 with the oxygen of the air, from which they derive 
 
122 MICROBES, FERMENTS, AND MOULDS. 
 
 materials for effecting oxidation. This is another 
 instance of the part played by microbes in artificial 
 fermentation. 
 
 Gayon and Dupetit believe that, in addition to 
 the microbes which produce nitre, there are others 
 which decompose the nitrates produced by the former. 
 When nitrate of potassium is placed in culture- 
 liquids, drain- water, chicken-broth, etc., it disappears 
 rapidly under the action of these microbes. Under 
 favourable conditions of temperature and environ- 
 ment, culture microbes daily reduce one gramme of 
 nitre to the litre. This decomposition causes the dis- 
 engagement of nitrogen, the formation of ammonia 
 and carbonic acid, which latter remain in solution in 
 the form of bicarbonate. Gayon and Dupetit believe 
 that this fact explains certain chemical phenomena 
 which occur in the soil, under the influence of manure 
 and water. 
 
 Thus fresh discoveries show more clearly every 
 day the importance of the part played by microbes 
 in nature. Agriculture, manufactures, geology, and 
 chemistry must take them into account, since they 
 are the active agents of a number of phenomena 
 which have hitherto been obscure in physics, 
 chemistry, and physiology. 
 
MICROBES, OR BACTERIA. 123 
 
 XII. THE MICROBES WHICH DESTROY BUILDING 
 MATERIALS. 
 
 The observations of Parize, director of the 
 agronomic station, Morlaix, lead to the belief that 
 microbes, which destroy dead bodies and effect such 
 various transformations in nature, not only attack 
 the beams of our houses, as we have already seen, but 
 building materials of an inorganic nature, including 
 stones. 
 
 On one occasion, when Parize was examining some 
 mucedinece which had vegetated on a brick partition, 
 in a closed and somewhat damp recess, he noticed 
 blisters on the coat of plaster. He broke one of these 
 blisters, and a line red dust, consisting of pulverized 
 brick, issued from it. When placed in the micro- 
 scope, under a magnifying power of about 300 
 diameters, he saw, amid schistoid fragments, dia- 
 tomatacea? and silicious algae pertaining to the original 
 clay of the bricks, an immense number of living 
 microbes : micrococcus, bacteria, amoeba), and ciliated 
 spores of algae, moving rapidly in the drop of water 
 used to moisten the dust. Some of these were in process 
 of budding. These organisms existed under a coat 
 of five to six mm. of plaster, and even of 00 mm. at 
 the bottom of a hole pierced by the brace; but in this 
 case they were less numerous, in the proportion of 
 two to three. The germs and spores which exist 
 
124 MICROBES, FERMENTS, AND MOULDS. 
 
 both in air and water may, therefore, be indefinitely 
 preserved in a protective medium, such as a brick 
 wall covered with plaster. They are nourished at 
 the expense of the ammoniacal salts which are found 
 in the air in a gaseous state, and which are fixed by 
 atmospheric moisture, and it is probable that they 
 derive' little nutriment from the solid materials in 
 the midst of which they live, although by their 
 increase disintegration may ensue. Hence, especially 
 from the hygienic point of view, it is so important to 
 disinfect the walls of hospitals, barracks, stables, etc., 
 by scraping and whitewashing them. 
 
 Parize also believes that microbes may perform 
 a geological part in nature by disintegrating the 
 schistoid rocks which enter into the constitution of 
 arable soil. But we are now speaking of microbes of 
 recent origin, since the temperature to which clay is 
 subjected in order to make red bricks would certainly 
 destroy all the microbes and their germs. This is not 
 the case with the microbes of chalk, which, according 
 to Bechamp, are of very ancient origin. 
 
 XIII. THE MICROBES OF CHALK AND COAL. 
 
 Be'champ's researches tend to show that microbes, 
 which he calls microzyma, or small ferments, have an 
 almost indefinite term of life. We know that chalk 
 consists almost entirely of the remains of the calcareous 
 
MICROBES, OK BACTERIA. 125 
 
 shell of Rhizopoda, protozoaria or microscopic animals 
 which lived in incalculable numbers in the seas of the 
 secondary period, and which still live at the bottom 
 of oceans. Bechamp holds that the organic substance 
 of these rhizopoda, or of the microbes which live in 
 their midst, has retained its vitality in the mass of 
 chalk, since a freshly cut piece, taken from the quarry 
 with all possible precautions to exclude air-germs, is 
 able to furnish microbes which multiply rapidly in 
 a favourable medium, and produce various fermenta- 
 tions. We have already seen that bacteria germs 
 resist desiccation, heat, and all kinds of destructive 
 influences, and remain for a long while, even for 
 several years, in the condition of dormant spores ; 
 but the existence of spores of the same kind in chalk 
 of the secondary period indicates a still more sur- 
 prising vitality. It is not, however, inexplicable if 
 we suppose that these microbes pass through 
 successive periods of activity and repose, and if we 
 compare these facts with those presented by the 
 microbes of saltpetre, of mineral waters, arid of the 
 anaerobic microbes, which are able to live when 
 deprived of the oxygen of the air. 
 
 Bechamp was the first to observe the presence of 
 granulations in coal, which appear under the micro- 
 scope to be microbes. These microbes must be far 
 more ancient than those of chalk, but they have lost 
 all vitality ; it has been found impossible to develop 
 them in infusions, and to obtain fermentations from 
 
126 MICROBES, FEIiMENTS, AND MOULDS. 
 
 f 
 
 them. Bat this cannot always have been the 
 and it has been supposed that the phenomenon of 
 coal formations, still so obscure and so variously 
 explained, was, at any rate, partially due to the 
 physiological labour of these microbes, and con- 
 sequently belongs to the class of fermentations. 
 
 XI V. CHROMOGEXIC MICROBES. 
 
 In addition to the colourless microbes, such as are 
 most of those we have hitherto considered, there are 
 others remarkable for their vivid and varied colours, 
 which betray their existence to the least practised 
 eyes. Many of these microbes attack our alimentary 
 substances, and should therefore be known to the 
 manufacturer and hygienist, since their action on 
 the human system is often injurious. 
 
 Many phenomena which have struck the imagina- 
 tion of ignorant and credulous people are merely due 
 to the presence of these coloured microbes. In 1819, 
 & peasant of Liguara, near Padua, was terrified by 
 the sight of blood-stains scattered over some polenta, 
 which had been made and shut up in a cupboard on 
 the previous evening. Next day similar patches 
 appeared on the bread, meat, and other articles of 
 food in the same cupboard. It was naturally regarded 
 as a miracle and warning from heaven, until the case 
 had been submitted to a Paduan naturalist, who easily 
 
MICROBES, OR liACTERIA. 127 
 
 ascertained the presence of a microscopic plant, which 
 Ehremberg likewise found at Berlin in analogous cir- 
 cumstances, and which he named Monas prodigiosa 
 At that time all microbes were confounded in the 
 Monad genus; we now term it Micrococcus pro- 
 digio&us. It has been observed not only on bread, 
 but on the Host, on milk, paste, and on all alimentary 
 or farinaceous substances exposed to damp heat. 
 
 This microbe has been recently studied by Raben- 
 horst, who declares that it is polymorphic, and has 
 received a number of different names : Palmetto, miri- 
 tica, Zoogalactina imetropha, Bacterium prodigivsum, 
 which are only varieties of Micrococcus prodigiosus, 
 modified by the medium in which it is nourished. 
 This observer noticed its appearance on cooked meat 
 kept in a cellar. The spherical cells, examined under 
 the microscope, were shown to be filled with a reddish 
 oil, which gave them a peach-blossom tint, and when 
 transferred to raw meat they assumed a splendid 
 fuchsia colour, resembling spots of blood. This plant 
 is only developed in the dark, and the nitrogen 
 necessary for its nutrition must be derived from the 
 air, especially when it is developed on bread, the 
 Host, etc., in which nitrogen is deficient. 
 
 When it is said to rain blood, this phenomenon is 
 likewise due to the presence of a minute plant, prob- 
 ably similar to that which often gives a red tint to 
 ponds and reservoirs in autumn. This microscopic 
 alga appears to be the one discovered by Ehremberg in 
 
 'TJJTIVIRSITY; 
 
128 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 1836, in a stream near Jena, and which he named Ophi- 
 domonas jenensis, or sanguined (Fig. 65). It is, on 
 account of its form, now placed in the genus Spirillum. 
 Like many other plants, it readily passes from green 
 to red. No one is surprised by the green scum 
 which covers reservoirs in summer, since it is so 
 common; but when this colour changes, often in a 
 single night, and passes from green to red, the unaccus- 
 tomed tint excites wonder, although it is caused by 
 
 Fig. 65. Ophidomonas sanguined of 
 stagnant water ^slighily magnified). 
 
 Fig. 66. t'rotococcusnivalis of 
 red snow ^magnified). 
 
 the same plant which was green the day before. If 
 there is a thunderstorm or waterspout which draws 
 up the red water from the ponds and reservoirs, and 
 discharges it in the form of rain on the surrounding 
 country, we hear of the phenomenon that it rains blood, 
 and it would be easy to find in the drops of rain the 
 reddish microbe which imparts this colour to them. 
 
 In northern regions the snow is often tinged with 
 the colour of blood by an analogous Micrococcus, which 
 
MICROBES, OR BACTERIA. 
 
 129 
 
 presents the same transition from green to red (Fig. 
 66). Green-tinted snow may be found adjacent to 
 the red snow, and under the microscope it displays 
 minute green globules, identical, except in colour, with 
 those of the red-tinted snow. 
 
 The variety of colour in these microbes is extreme. 
 Micrococcus aurantiacus gives an orange colour to 
 
 Fig. 67. Bacterium cyanogenum, microbe of blue milk (Neelsen). It is probable 
 that several different forms are here contused under this name. B, zoogloea. 
 
 bread and eggs; M. chlorinus is grass-green ; M. cyanus 
 is of a beautiful azure blue ; M. violaceus is violet or 
 lilac, and M. fulvus is rust-coloured. These have all 
 been observed on food. M. candidus forms little 
 white patches upon cheese. 
 
 The genus Bacterium also furnishes its contingent 
 of coloured species ; such are B. xanthinum and 
 10 
 
130 MICROBES, FERMENTS, AND MOULDS. 
 
 B. cyanogenum, which give respectively a yellow 
 or blue colour to milk (Fig. 67). Peasants say that 
 an evil eye has been cast upon the milk, but it is 
 easy to prove that the development of these microbes 
 is due to imperfect cleansing of the tin milk-vessels, 
 since the discolouration ceases when greater care is 
 taken to wash and scald the vessels. 
 
 Bread often displays microscopic growths of a 
 dark green or orange colour, and in this state it 
 cannot be introduced into the stomach without 
 danger. In the first case it is Bacterium cerugi- 
 nosum, in the second Micrococcas aurantiacus. The 
 badly made and badly baked bread of the French 
 peasants, which is often kept for a fortnight or more, 
 exposed to the moisture and heat which favour the 
 development of these microbes, sometimes displays 
 the first of these changes ; the second is particularly 
 common in soldiers' bread, which must likewise be 
 baked several days in advance, and which is conveyed 
 in carts exposed to the weather. Megnin recently 
 observed a cryptogamic growth of this kind on the 
 bread distributed to the garrison of Vincennes. 
 
 The spores of these microbes are found in flour, 
 and resist a temperature of 120, while they are 
 destroyed by that of 140. Thus they are no longer 
 found in the crust, of which the temperature rises 
 to 200 ; but may easily subsist in the much lower 
 temperature of the crumb. Hence the necessity of 
 only using flour perfectly free from germs. 
 
MICROBES, OR BACTERIA. 131 
 
 The pus of wounds is often coloured blue by 
 an aerobic micrococcus, of which the protoplasm is 
 colourless, but which makes a colouring matter 
 called pyocyanine, and this gives a blue tint to the 
 lint and bandages used for dressing the wound. 
 
 XV. THE MICROBE OF BALDNESS. 
 
 In addition to the numerous parasitic fungi of 
 skin on which the hair grows thickly, which we 
 have already noticed, the human hair is attacked 
 by a true microbe, which is, according to the re- 
 searches of Gruby, Malassez and Thin, the cause of 
 Alopecia areata, one form of baldness. The parasite 
 has the appearance of a micrococcus, and penetrates 
 the interior of the hair, which is, as we know, hollow. 
 The hair must be made transparent by potash, in order 
 to see the microbe. It probably penetrates between 
 the bulb and the hair-follicle as far as the root, is 
 introduced into the hair, and multiplies and gradually 
 rises higher in it, until the substance is disorganized. 
 This microbe has been called Bactei mm decalvane. 
 
MICROBES, FEKMENTJS, AND MOULDS. 
 
 CHAPTER IV. 
 
 MICROBES OF THE DISEASES OF OUR DOMESTIC ANIMALS. 
 
 I. ANTHRAX, OR SPLENIC FEVER. 
 
 THE first of the virulent and contagious diseases in 
 which the presence of a microbe was positively 
 ascertained was anthrax, or splenic fever, which 
 attacks most of our horned animals, and especially 
 cattle and sheep. 
 
 As early as 1850, Davaine had observed the 
 presence of minute rods in the blood of animals which 
 died of splenic fever; but it was only in 1863, after 
 Pasteur's first researches into the part played by 
 microbes in fermentations, that Davaine suspected 
 these rods of being the actual cause of the disease. 
 He inoculated healthy animals with the tainted blood, 
 and thus ascertained that even a very minute dose 
 would produce a fatal attack of the disease, and the 
 rods, to which he gave the name of Bacteridia, could 
 always be discovered in enormous numbers in the 
 blood. 
 
ANTHRAX. 
 
 133 
 
 The microbe so named by Davaine must from its 
 characteristics be assigned to the genus Bacillus, and 
 is now termed Bacillus anthracis. This disease, 
 which affects men as well as animals, is characterized 
 by general depression, by redness and congestion of 
 the eyes, by short and irregular respiration, and by 
 the formation of abscesses, which feature, in the case 
 of the human subject, has procured for it the name of 
 malignant pustule. The disease is quickly terminated 
 
 Fig. 68. Bacillus anthracis of splenic fever in different stages of development: 
 bacilli, spores, and curled filaments (much enlarged). 
 
 by death, and an autopsy shows that the blood is 
 black, that intestinal hsemorrhage has occurred, and 
 that the spleen is abnormally large, heavy, and gorged 
 with blood ; hence the name of splenic fever. The 
 disease is generally inoculated by the bite of flies 
 which have settled upon carcases and absorbed the 
 bacteria, or by blood-poisoning through some accidental 
 scratch, and this is especially the case with knackers 
 
134 MICROBES, FERMENTS, AND MOULDS. 
 
 and butchers who break and handle the bones of 
 animals which have died of anthrax. 
 
 The period of incubation is very short. An ox 
 which has been at work may return to the stall 
 apparently healthy. He eats as usual ; then lies down 
 on his side and breathes heavily, while the eyes are 
 still clear. Suddenly his head drops, his body grows 
 cold ; at the end of an hour the eye becomes glazed ; 
 the animal struggles to get up, and falls dead. In 
 this case, the illness has only lasted for an hour and 
 a half (Ernpis). 
 
 Fig. 69. Bacillus anthracis, produced in pulnea-pig by inoculation: corpuscles of 
 blood and bacilli. 
 
 In order to prove that the disease is really caused 
 by Bacillus anthracis, Pasteur inserted a very small 
 drop of blood, taken from an animal which had 
 recently died of anthrax, in a glass flask which con- 
 tained an infusion of yeast, neutralized by potassium 
 and previously sterilized. In twenty-four hours the 
 liquid, which had been clear, was seen to be full of 
 very light flakes, produced by masses of bacilli, readily 
 
ANTHRAX. 135 
 
 discernible under the microscope. A drop from the 
 first flask produced the same effect in a second, and 
 from that to a third, and so on. By this means the 
 organism was completely freed from all which was 
 foreign to it in the original blood, since it is calculated 
 that after from eight to ten of such processes, the 
 drop of blood was diluted in a volume of liquid 
 greater than the volume of the earth. Yet the tenth, 
 twentieth, and even the fiftieth infusion would, when 
 a drop was inserted under the skin of a sheep, procure 
 its death by splenic fever, with the same symptoms 
 as those produced by the original drop of blood. The 
 bacillus is, therefore, the sole cause of the disease. 
 
 These cultures have often since been repeated by 
 numerous observers, so that the microbe has been 
 studied in all its forms, and the extent of its poly- 
 morphism has been ascertained. At .the end of two 
 days the bacterium, which, while still in the blood, 
 is of a short, abrupt form, displays excessively long 
 filaments, which are sometimes rolled up like a coil 
 of string. In about a week many of the filaments 
 contain refracting, somewhat elongated nuclei. These 
 nuclei presently form chaplets, in consequence of the 
 rupture of the cell- wall of the rod which gave birth 
 to them ; others, again, float in the liquid in the form 
 of isolated globules. These nuclei are the spores or 
 germs of the microbes, which germinate when placed 
 in the infusion, become elongated, and reproduce fresh 
 bacilli. 
 
MICROBES, FERMENTS. AND MOULDS. 
 
 These spores are much more tenacious of life than 
 the microbes themselves. The latter perish in a tempe- 
 rature of 60, by desiccation, in a vacuum, in carbonic 
 acid, alcohol, and compressed oxygen. The spores 
 on the other hand, resist desiccation, so that they can 
 float in the air in the form of dust. They also resist 
 a temperature of from 90 to 95, and the effects of a 
 vacuum, of carbonic acid, of alcohol, and compressed 
 oxygen. 
 
 In 1873, Pasteur, aided by Chamberland and Roux, 
 carried on some experiments on a farm near Chartres, 
 in order to discover why this disease is so common in 
 some districts, in which its spread cannot be ascribed 
 to the bite of flies. Grass, on which the germs of 
 bacteridia had been placed, was given to the sheep. 
 A certain number of them died of splenic fever. The 
 glands and tissues of the back of the throat were 
 very much swelled, as if the inoculation had occurred 
 in the upper part of the alimentary canal, and by 
 means of slight wounds on the surface of the mucous 
 membrane of the mouth. In order to verify the fact, 
 the grass given to the sheep was mixed with thistles 
 and bearded ears of wheat and barley, or other prickly 
 matter, and in consequence the mortality was sensibly 
 increased. 
 
 In cases of spontaneous disease it was surmised 
 that the germs which were artificially introduced into 
 food in the course of these experiments, are found 
 upon the grass, especially in the neighbourhood of 
 
ANTHRAX. 
 
 places in which infected animals had been buried. It 
 was, in fact, ascertained that these germs existed 
 above and around the infected carcases, and that they 
 were absent at a certain distance from their burial- 
 place. It is true that putrid fermentation destroys 
 most of the bacteria, but before this occurs a certain 
 number of microbes are dispersed by the gas dis- 
 engaged from the carcase; these dry up and produce 
 germs, which retain their vitality in the soil for a 
 long while. 
 
 The mechanism by means of which these germs 
 are brought to the surface of the soil and on to the 
 grass on which the sheep feed is at once simple and 
 remarkable. Earth-worms prefer soils which are rich 
 in humus or decomposing organic substance, and seek 
 their food round the carcase. They swallow the earth 
 containing the germs of which we have spoken, which 
 they deposit on the surface of the soil, after it has 
 traversed their intestinal canals, in the little heaps 
 with which we are all acquainted. The germs do not 
 lose their virulence in their passage through the 
 worms' intestines, and if the sheep swallow them 
 together with the grass on which they browse, they 
 may contract the disease. The turning-up of the soil 
 by the spade or plough may produce the same effect. 
 
 A certain warmth is necessary for the formation 
 of germs; none are produced when it falls below 12, 
 and the carcases buried in winter are therefore less 
 dangerous than those buried in the spring and sum- 
 
138 HlCltOLiES, FERMENTS, AND MOULDS. 
 
 raer. It is, in fact, in hot weather that the disease 
 is most prevalent. Animals may, however, contract 
 it even in their stalls from eating dry fodder on which 
 germs of these bacteria remain. 
 
 Pasteur and his pupils performed an experiment 
 in the Jura in 1879, which clearly shows that the 
 presence of germs above the trenches in which car- 
 cases have been buried is the principal cause of 
 inoculation. Twenty oxen or cows had perished, and 
 several of them were buried in trenches in a meadow 
 where the presence of these germs was ascertained. 
 Three of the graves were surrounded by a fence, 
 within which four sheep were placed. Other sheep 
 were folded within a few yards of the former, but in 
 places where no infected animals had been buried. 
 At the end of three days, three of the sheep folded 
 above the graves had died of splenic fever, while those 
 excluded from them continued to be healthy. This 
 result speaks for itself. 
 
 Malignant pustule, which is simply splenic fever, 
 affects shepherds, butchers, and tanners, who handle 
 the flesh and hide of tainted animals. Inoculation 
 with the bacillus almost always occurs in consequence 
 of a wound or scratch on the hands or face. In Ger- 
 many, fatal cases of anthrax have been observed, in 
 which the disease has been introduced through the 
 mouth or lungs, as in the case of the sheep observed 
 by Pasteur. The human subject appears, however, 
 to be less apt to contract the disease than herbivora, 
 
ANTHEAX. 139 
 
 since the flesh of animals affected by splenic fever, 
 and only killed when the microbe is fully developed 
 in the blood, is often eaten in farmhouses. In this 
 case the custom prevalent among French peasants of 
 eating over-cooked meat constitutes the chief safeguard, 
 since the bacteria and their germs are thus destroyed. 
 
 II. VACCINATION FOR ANTHRAX. 
 
 The rapidity with which anthrax is propagated 
 by inoculation generally renders all kinds of treat- 
 ment useless ; if, however, the wound through which 
 the microbe is introduced can be discovered, it should 
 be cauterized at once. This method is often successful 
 in man. The pustule is cauterized with red-hot iron, 
 or with bichloride of mercury and thymic acid, two 
 powerful antiseptics, certain to destroy the bacteridium. 
 It is expedient, as an hygienic measure, to burn the 
 tainted carcases, and if this is not done, they should 
 be buried at a much greater depth than is usually the 
 case. 
 
 But the preservative means on which chief re- 
 liance is now placed is vaccination with the virus 
 of anthrax. Pasteur has ascertained that when 
 animals are inoculated with a liquid containing bac- 
 teridia of which the virulence has been attenuated 
 by culture carried as far as the tenth generation, or 
 even further, their lives are preserved. They take 
 
140 MICROBES, FERMENTS, AND MOULDS. 
 
 the disease, but generally in a very mild form, arid it 
 is an important result of this treatment that they are 
 henceforward safe from a fresh attack of the disease ; 
 in a word, they are vaccinated against anthrax. 
 
 In the cultures prepared with the view of attenu- 
 ating the microbe, it is the action of the oxygen of 
 the air which renders the bacteridium less virulent. 
 It should be subjected to a temperature of from 42 
 to 43 in the case of Bacillus anthracis, to enable it 
 to multiply, and at the same time to check the pro- 
 duction of spores which might make the liquid too 
 powerful. At the end of the week, the culture, which 
 at first killed the whole of ten sheep, killed only four 
 or five out of ten. In ten or twelve days it ceased 
 to kill any ; the disease was perfectly mild, as in the 
 case of the human vaccinia, of which we shall speak 
 presently. After the bacteridia have been attenuated, 
 they can be cultivated in the lower temperature of 
 from 30 to 35, and only produce spores of the same 
 attenuated strength as the filaments which form them 
 (Chamberland). 
 
 The vaccine thus obtained in Pasteur's laboratory 
 is now distributed throughout the world, and has 
 already saved numerous flocks from almost certain 
 destruction. Although this process has only been 
 known for a few years, its results are such that the 
 gain to agriculture already amounts to many thousands 
 of pounds. 
 
 Toussaint makes use of a slightly different mode 
 
ANTHRAX. 141 
 
 of preparing a vaccine virus, which is, however, 
 analogous to that of Pasteur. He subjects the lymph 
 of the blood of a diseased animal to a temperature 
 of 50, and thus transforms it into vaccine. Toussaint 
 considers the high temperature to be the principal 
 agent of attenuation, and ascribes little or no im- 
 portance to the action of the oxygen in the air. 
 
 Chamberland and Roux have recently made re- 
 searches with the object of obtaining a similar 
 vaccine by attenuating the primitive virus by means 
 of antiseptic substances. They have ascertained that 
 a solution of carbolic acid of one part in six hundred 
 destroys the microbes of anthrax, while they can live 
 and nourish in a solution of one part in nine hundred, 
 but without producing spores, and their virulence is 
 attenuated. When a nourishing broth is added to 
 a solution of one in six hundred, the microbe can live 
 and grow in it for months. Since the chief condition 
 of attenuation consists in the absence of spores, this 
 condition seems to be realized by the culture in a 
 solution of carbolic acid, one in nine hundred, and it 
 is probable that a fresh form of attenuated virus 
 may thus be obtained. Diluted sulphuric acid gives 
 analogous results. 
 
 However this may be, the vaccine prepared by 
 Pasteur's process is the only one which has been 
 largely used, and which has afforded certain results to 
 cattle-breeders. 
 
 Public experiments, performed before com mis- 
 
142 MICROBES, FEIIMENTS, AND MOULDS. 
 
 sions composed of most competent men, have clearly 
 shown the virtue of the protective action. In the 
 summer of 1881, the initiation was taken by the 
 Melun Society of Agriculture. Twenty-five sheep and 
 eight cows or oxen were vaccinated at Pouilly-le-Fort, 
 and then re-inoculated with blood from animals which 
 had recently died of anthrax, together with twenty- 
 five sheep and five cows which had not been previously 
 vaccinated. None of the vaccinated animals suffered 
 while the twenty-five test sheep died within forty- 
 eight hours, and the five cows were so ill that the 
 veterinary surgeons despaired of them for several 
 days. 
 
 This experiment was publicly repeated in Sep- 
 tember, 1881, by Thuillier, Pasteur's fellow- worker, 
 whose death we have recently had to deplore, before the 
 representatives of the Austro -Hungarian Government ; 
 and again near Berlin, in 1882, before the representa- 
 tives of the German Government, and always with 
 the same success. Up to April, 1882, more than 
 130,000 sheep and 2000 oxen or cows had been vac- 
 cinated ; and since that time the demand for vaccine 
 from Pasteur's laboratory has reached him from every 
 quarter. 
 
 III. FOWL CHOLERA. 
 
 The sickness of barn-door poultry, which is com- 
 monly called cholera, is caused by the presence in the 
 
OTHER DISEASES OF DOMESTIC ANIMALS. 143 
 
 blood of a small micrococcus or bacterium in the form 
 of the figure 8, differing, therefore, in form from Bacil- 
 lus anthracis, but also an aerobie. It may be cultivated 
 in chicken-broth, neutralized by potash, while it soon 
 dies in the extract of yeast, which is so well adapted 
 to Bacillus anthracis. 
 
 The microbe of this disease may also be attenuated 
 by culture, and it may be done more easily than in 
 the case of anthrax, since it is not necessary to raise 
 the temperature, as the bacterium of fowl-cholera does 
 not produce spores under culture. Pasteur has there- 
 fore been able to prepare an attenuated virus well 
 adapted to protect fowls from further attacks of this 
 disease. 
 
 IV. SWINE FEVER. 
 
 The disease affecting swine, which is called rougct, 
 or swine fever, in the south of France, has been 
 recently studied by Detmers in the United States, 
 where it is also very prevalent, and by Pasteur in 
 the department of Vaucluse. It is a kind of pneumo- 
 enteritis. 
 
 These observers consider that the disease is caused 
 by a very slender microbe, formed, like that of fowl- 
 cholera, in the shape of the figure 8, but more minute. 
 Others say that there is a bacillus which was observed 
 by Klein as early as 1878 in swine attacked by this 
 disease. In spite of the apparent contradiction, it is 
 
144 MICROBES, FERMENTS, AND MOULDS. 
 
 probable that we have only two forms of the same 
 microbe, for the bacillus in Klein's culture at first 
 resembles Bacterium termo, in the form of an 8, before 
 it is elongated into rods. 
 
 Pasteur has succeeded in making cultures of 
 microbes in the figure 8. He has inoculated swine 
 with the attenuated form, after which they have been 
 
 Fig. 70. Swine fever: section of a lymphatic gland, showirg a blood-vessel filled with 
 microbes (.much enlarged: Klein). 
 
 able to resist the disease, so there is reason to hope 
 that in the near future this new vaccine, containing 
 the attenuated microbe, may become the safeguard of 
 our pig-sties. 
 
 V. OF SOME OTHER DISEASES PECULIAR TO DOMESTIC 
 ANIMALS. 
 
 An epidemic which raged in Paris in 188 L was 
 called the typhoid fever of horses, and was fatal to 
 more than 1500 animals belonging to the General Om- 
 nibus Company in that city. This disease is also pro- 
 
OTHER DISEASES OF DOME&TIC ANIMALS. 145 
 
 duced by a microbe, with which Pasteur was able to 
 inoculate other animals (rabbits) ; for this purpose 
 he made use of the serous discharge from the horses' 
 nostrils. The inoculated rabbits died with all the 
 symptoms and lesions characteristic of the disease. 
 
 The attenuation of this microbe by culture is 
 difficult, since at the end of a certain time the action 
 of the air kills it. Pasteur has, however, found an 
 expedient by which to accomplish his purpose. When 
 tiie culture is shown to be sterile in consequence of 
 the death of the microbe, he takes as the mother 
 culture of a fresh series of daily cultures the one which 
 was made on the day preceding the death of the first 
 mother culture. In this way he has obtained an 
 attenuated virus with wnich to inoculate rabbits, and 
 the same result might undoubtedly be obtained in 
 the case of horses. 
 
 There are many other contagious diseases which 
 affect domestic animals, and which are probably due to 
 microbes, such as, for instance, the infectious pneumonia 
 of horned cattle. This was probably the first disease in 
 which the protective effects of inoculation were tried 
 according to Wilhelm's method. This method consisted 
 in making an incision under the animal's tail with a 
 scalpel dipped in the purulent mucus or blood taken 
 from the lung of a beast which had died of pneumonia ; 
 sometimes the serous discharge from the swelling under 
 the tail of an inoculated animal was used for others. 
 Fever and loss of appetite ensued, lasting from eight 
 
146 MICROBES, FERMENTS, AND MOULDS. 
 
 to twenty-five days, but the animal was afterwards 
 safe from further attacks of the disease. 
 
 Cattle plague, or contagious typhus, is likewise 
 ascribed to the presence of a microbe with which we 
 are as yet imperfectly acquainted. 
 
 Experimental septicemia is entitled to special men- 
 tion, since it has too often been confounded with 
 anthrax, and has been unskilfully produced with the 
 intention of vaccinating animals in accordance with 
 Pasteur's process. This occurs when too long an 
 interval (twenty-four hours) elapses after the death of 
 
 Fig. 71. Sept'c vibrio, bacillus of malignant cpdema (Kocli) : , taken from spleen of 
 guiueu-p.g; U, irom a moute's lung. 
 
 an animal, before taking from it the blood intended for 
 vaccine cultures. After this date the blood no longer 
 contains Bacillus anthracis, which is succeeded by 
 another microbe termed Vibrio septicus, differing 
 widely from the anthrax microbe in form, habit, and 
 character (Fig. 71). Bacillus anthracis is straight and 
 immobile, while the septic vibrio is sinuous, curled, 
 and mobile. Moreover, it is anaerobic, and does not 
 survive contact with the air, but it thrives in a vacuum 
 or in carbonic acid. Since Bacillus anthracis is, on 
 
OTHER DISEASES OF DOMESTIC ANIMALS. 147 
 
 the other hand, an aerobie, it is clear that the two 
 microbes cannot exist simultaneously in the blood or 
 in the same culture liquid. 
 
 The inoculation with this fresh microbe is no less 
 fatal ; its action is even more rapid than that of 
 Bacillus anthracis, but the lesions are not the same ; the 
 spleen remains normal, while the liver is discoloured. 
 
 The septic vibrio is only found in minute quantities 
 in the blood, so that it has escaped the notice of many 
 observers. It is, however, found in immense numbers 
 in the muscles, in the serous fluid of the intestines, and 
 of other organs. It is very common in the intestines, 
 and is probably the beginning of putrefaction. 
 
 VI. RABIES. 
 
 Rabies is a canine disease which is communicated 
 by a bite, and the inoculation of man and other 
 animals by the saliva. We are not yet precisely 
 acquainted with the microbe which causes the disease, 
 but Pasteur's recent researches have thrown consider- 
 able light on its life-history, which is still, however, 
 too much involved in obscurity. 
 
 It must first be observed that the hypothetical 
 microbe of rabies, which no one has yet discovered, 
 should not be confounded with the microbe of human 
 saliva ; this is found in the mouths of healthy persons, 
 and will be briefly discussed in the following chapter. 
 
148 MICROBES, FERMENTS, AND MOULDS 
 
 The following conclusions are the result of Pasteur's 
 researches into the virus of rabies. 
 
 This virus is found in the saliva of animals and men 
 affected by rabies, associated with various microbes. 
 Inoculation with the saliva may produce death in three 
 forms : by the salivary microbe, by the excessive 
 development of pus, and finally by rabies. 
 
 The brain, and especially the medulla oblongata, of 
 men and animals which have died of rabies, is always 
 virulent until putrefaction has set in. So also is 
 the spinal cord. The virus is, therefore, essentially 
 localized in the nervous system. 
 
 Rabies is rapidly and certainly developed by tre- 
 phining the bones of the cranium, and then inocu- 
 lating the surface of the brain with the blood or saliva 
 of a rabid animal. In this way there is a suppression 
 of the long incubation which ensues from simple 
 inoculation of the blood by a bite or in tra- venous 
 injection on any part of the body. It is probable that 
 in this case the spinal cord is the first to be affected 
 by the virus introduced into the blood; it then fastens 
 on its tissues and multiplies in them. 
 
 As a general rule, a first attack which has not proved 
 fatal is no protection against a fresh attack. In 1881, 
 however, a dog which had displayed the first symptoms 
 of the disease of which the other animals associated 
 with him had died, not only recovered, but failed to 
 take rabies by trephining, when re-inoculated in 1882. 
 Pasteur is now in possession of four dogs which are 
 
OTHER DISEASES OF DOMESTIC ANIMALS. 149 
 
 absolutely secured from infection, whatever be the mode 
 of inoculation, and the intensity of the virus. All the 
 other test dogs which were inoculated at the same 
 time died of rabies. In 1884, Pasteur found the means 
 of attenuating the virus. For this purpose he has 
 inoculated a morsel of the brain of a mad dog into a 
 rabbit's brain, and has passed the virus proceeding 
 from the rabbit through the organism of a monkey, 
 whence it becomes attenuated and a protective vaccine 
 for dogs. This is the first step towards the extinction 
 of this terrible disease. 
 
 VII. GLANDERS. 
 
 This, again, is a disease easily transmitted from 
 horses to man. Glanders, or farcy, is caused by the 
 presence of a bacterium, observed as early as 1868 
 by Christot and Kiener, and more recently studied at 
 Berlin by Schiitz and Lofler. This microbe appears 
 in the form of very fine rodt (bacillus) in the lungs, 
 liver, spleen, and nasal cavity. Babes and Havas 
 found this bacillus in the human subject in 1881. 
 Experimental cultures have been made simultaneously 
 in France and Germany, and have given identical 
 results. 
 
 Bouchard, Capitan, and Charrin made their cultures 
 in neutralized solutions of extract of meat, maintained 
 at a temperature of 37. By means of successive 
 sowings, they have obtained the production of un- 
 
150 MICROBES, FERMENTS, AND MOULDS. 
 
 mixed microbes, presenting no trace of the original 
 liquid, and this was done in vessels protected from air- 
 germs. These cultures may be carried to the eighth 
 generation. 
 
 Asses and horses inoculated with liquid containing 
 the microbes produced by this culture have died with 
 the lesions characteristic of glanders (glanderous 
 tubercles in the spleen, lungs, etc.). Cats and other 
 animals which have been inoculated in the same way 
 die with glanderous tubercles in the lymphatic glands 
 and other organs. 
 
 It follows from these experiments that the microbe 
 which causes this disease is always reproduced in the 
 different culture liquids with its characteristic form 
 and dimensions ; that uni-ungulates can be inoculated 
 with it, as well as man and other animals. In fact, this 
 microbe is the essential cause of the disease. 
 
 VIII. PEBRINE AND FLACHERIE, DISEASES AFFECTING 
 SILKWORMS. 
 
 We have already spoken of muscardine, a silk- 
 worm's disease produced by a microscopic fungus ; 
 two other diseases are caused by distinct microbes, of 
 which we must shortly speak. 
 
 Pebrine. In the silkworm nurseries, in which this 
 disease prevails, the silkworms which issue from the 
 eggs, technically called seed, are slowly and irregularly 
 developed, so as to vary greatly in size. Many die 
 
OTHEK DISEASES OF DOMESTIC ANIMALS. 151 
 
 young, and those which survive the fourth moult 
 shrink and shrivel away ; they can hardly creep on to 
 the heather to spin their cocoon, and produce scarcely 
 any silk. 
 
 On an examination of the worms which have died 
 of this disease, De Quatrefages ascertained the presence 
 of minute stains on the skin and in the interior of 
 the body, which he compared to a sprinkling of 
 black pepper; hence the name pebrine. Under the 
 microscope these stains assume the form of small 
 mobile granules like bacteria, which Cornalia termed 
 vibratile corpuscles, on account of their movements. 
 Finally, Osimo and Vittadirii ascertained the existence 
 of these corpuscles in the eggs, and consequently 
 showed that the epidemic might be averted by the 
 sole use of healthy eggs, of which the soundness 
 should be established by microscopic examination. 
 
 It was at about this date, 1865, that Pasteur under- 
 took the exhaustive study of pebrine; but Bechamp 
 was the first to pronounce the disease parasitic, 
 resembling muscardine in this respect, and caused by 
 the attacks of a microbe or rnicrozyma, to adopt 
 Bechamp's name of which the germ or spore is derived 
 from the air, at first attacking the silkworm from 
 without, but multiplying in its interior, and developing 
 with its growth, so that the infected moth is unable 
 to lay its eggs without depositing the spores of the 
 microbe at the same time, and thus exposing the 
 young grub to attack as soon as it is born. Pasteur's 
 
152 MICROBES, FERMENTS, AND MOULDS. 
 
 own researches soon induced him to adopt the 
 same view. 
 
 The pebrine microbe was long regarded as a true 
 
 bacterium, successively described as Bacterium 6om- 
 
 bycis, Nosema bombycis (Fig. 72), and 
 
 0"'^ & Panistophyton ovale. Balbiani's recent 
 
 * 0^0 ^ researches tend to show that it should 
 
 ^ Q o be assigned to another group, much 
 
 9 nearer to animals, and designated 
 
 Fig. 72. Nosema SpOTOZOOLria, 
 
 bombycis, pebrine 9 
 
 microbe (x 500 SpoTozoaria. These protista, still 
 
 regarded as plants by many naturalists, 
 chiefly differ from bacteria by their mode of growth 
 and reproduction, in which they resemble the para- 
 sitic protozoaria, termed Psorospermia, Coccidies, and 
 Gregarinidce. 
 
 In Sporozoaria, growth by fission, the rule in all 
 bacteria, has not been observed ; this distinction is 
 fundamental. Sporozoaria multiply by free spore- 
 formation in a mass of sarcode substance (protoplasm), 
 resulting from the encysting of the primitive corpuscles 
 (mother-cells). The formation of numerous spores 
 may be observed within the mother-cells, having the 
 appearance of pseudonavicellce or spores of gregari- 
 nidaeand psorospermia (parasites of vertebrate animals). 
 Balbiani forms these organisms, which are found in 
 many insects, into a small group, which he terms 
 Microsporidia. 
 
 The ripe spores are the vibratile corpuscles of 
 
OTHER DISEASES OF DOMESTIC ANIMALS. 153 
 
 Cornalia. They closely resemble the spores of some 
 bacilli (B. amylobacter, for instance), and their germi- 
 nation is likewise effected by perforation of the spore 
 at one end, and issue of the protoplasm from the 
 interior. This, however, does not issue in a rod-]iko 
 form (Bacillus), but in that of a small protoplasmic 
 mass, with amoeboid movements, a characteristic not 
 observed in any bacterium (Balbiaui). 
 
 The other species of silkworms which have been 
 recently introduced, notably, the oak silkworm from 
 China (Attacus Pemyi), are attacked by microsporiclia 
 analogous to those of pebrine. 
 
 Pasteur has indicated the mode of averting the 
 ravages of this disease. He has thus addressed the 
 breeders : " If you wish to know whether a lot of 
 cocoons will yield good seed, separate a portion of them 
 and subject them to heat, which will accelerate the 
 escape of the moth by four or five days, and examine 
 them under the microscope to ascertain whether cor- 
 puscles of pebrine are present. If they are, send all the 
 cocoons to the silk factory. If they are not diseased, 
 allow them to breed, and the seed will be good and 
 will hatch out successfully. In a word, start with 
 absolutely healthy seed, produced by absolutely pure 
 parents, and rear them under such ^conditions of 
 cleanliness and isolation as may ensure immunity 
 from infection." 
 
 When the disease is developed, fumigation with 
 sulphurous acid is recommended, or preferably with 
 
154 MICROBES, FERMENTS, AND MOULDS. 
 
 creosote or carbolic acid, which do not affect the silk- 
 worms (Bechamp), and which hinder the development 
 of microsporidia. These fumigations likewise keep 
 the litter from becoming corrupt, and in a properly 
 conducted nursery the litter is kept dry. 
 
 Flacherie. Wrongly confounded with pebrine, the 
 disease flaclierie is still more destructive to silkworms. 
 The symptoms are remarkable. The rearing of silk- 
 worms often goes on regularly up to the fourth moult, 
 and success seems assured, when the silkworms suddenly 
 cease to feed, avoid the leaves, become torpid, and 
 perish, while still retaining an appearance of vitality, 
 so that it is necessary to touch them in order to ascer- 
 tain that they are dead. In this state they are termed 
 morts-flats. A few days, sometimes even a few hours, 
 suffice to transform the most flourishing nursery into 
 a charnel-house. 
 
 Pasteur examined these morts-flats, and found that 
 the leaves contained in the stomach and intestine were 
 full of bacteria, resembling those which are developed 
 when the leaves are bruised in 
 a glass of water and left to putrefy 
 (Fig. 73). In a healthy specimen. 
 of good digestion, these bacteria 
 
 are never found. It is therefore 
 evident that the disease is owing 
 to bad digestion, and becomes rapidly fatal in animals 
 which consume an enormous amount of food, and do 
 nothing but eat from morning to night. The digestive 
 
 ** 
 
 *o ~\ 
 
 /' o/ 
 
OTHER DISEASES OF DOMESTIC ANIMALS. 
 
 ferments of unhealthy silkworms do not suffice to 
 destroy the bacteria of the leaves, nor to neutralize 
 their injurious effects. 
 
 These bacteria are really the cause of the disease, 
 for if even a minute quantity of the leaves taken from 
 the intestine of diseased silkworms be given to healthy 
 specimens, they soon die of the same disease. It is, 
 therefore, essentially contagious, and in order to prevent 
 the diseased silkworms from contaminating the healthy 
 by soiling the leaves on which the latter are about to 
 feed, as much space should be assigned to them as 
 possible. 
 
 Good seed should also be selected, since it has been 
 ascertained that some lots of seed are more liable to 
 the disease than others. The affection does not indeed 
 begin in the egg, as in pebrine, but the question of 
 heredity comes in. It is clear that when a silkworm 
 has been affected by flacherie without dying of it, its 
 eggs will have little vitality, and the grubs which issue 
 from them will be predisposed by their feeble constitu- 
 tion to contract the disease. 
 
MICU013ES, Jj'JiliMENTti, AND MOULDS 
 
 CHAPTER V. 
 
 THE MICROBES OF HUMAN DISEASES. 
 
 I MICROBES OF AIR, EARTH, AND WATER. 
 
 IT is generally admitted that the large majority of 
 epidemic and contagious diseases which affect men 
 and animals are caused by the introduction of certain 
 kinds of microbes into the organism. In reply to the 
 question how these microbes are introduced into the 
 body, and where they are before entering it, it is easy 
 to show that these microbes exist in immense numbers 
 they or their spores in the air we breathe, in the 
 water we drink, in the ground on which we tread, 
 and whence there rises, whenever it is dry, a fine dust 
 charged with all sorts of germs, which penetrate 
 together with the air into our mouths and lungs. 
 
 For a long while we were almost completely 
 ignorant of the conditions of existence of these 
 microbes when they are in the soil or water. The 
 recent researches of Zopf, a German botanist, tend to 
 show that among the inferior algae termed Bacteria 
 
THE MICROBES OF HL'^JWMW^3pgr 157 
 
 or Schizophyta, there is a very remarkable dimorphism 
 of mode and habitat. In Beggiatoa of sulphurous 
 waters, for instance, and in Cladothrix, which forms a 
 whitish pellicle on the surface of putrefying liquids, 
 Zopf has found, under certain conditions, all the forms 
 designated as Micrococcus, Bacillus, Leptothrix, and 
 Bacterium ; that is, microbes strictly so called, in- 
 cluding those which are the producing agents of 
 contagious diseases. 
 
 Where these algae are found in water or on a damp 
 soil, conditions of existence favourable to their develop- 
 ment, there they live and multiply. But when the 
 soil dries up, when a river returns to its bed after 
 a flood, or a marsh disappears in consequence of the 
 evaporation of its waters, all these algaa give forth 
 dormant spores, destined to ensure their propagation. 
 We have described the formation of these spores by 
 concentration of the protoplasm in the interior of 
 each cell ; in this form their volume is very small, and 
 they are extremely light, so that as soon as they are 
 desiccated, and then only, these spores are carried 
 away by the slightest breeze and borne to great dis- 
 tances. These are termed air-germs. 
 
 When these moving germs encounter a favourable 
 medium, at once moist and warm, such as the human 
 mouth or lungs, they fasten there and are immediately 
 developed, first in the form of Micrococcus, then of 
 that of Bacterium, Bacillus, or Leptothrix, according 
 to the species to which the spore in question belongs. 
 
158 MICttOBES, FERMENTS, AND MOULDS. 
 
 Schizophyta may therefore have two very different 
 modes of existence, comparable to the hetersecia (change 
 of habitat) and dimorphism of the fungi Ascomycetes 
 and Basidiomycetes. Schizomycetes however, although, 
 like fungi, they obtain their nourishment from organic 
 substances which have been already elaborated, are 
 not true parasites in the first stage of their existence, 
 during which stage they live freely in the water, or on 
 the damp soil. They become true parasites when they 
 penetrate into the blood and tissues of man, in which 
 they necessarily live at the expense of their host. 
 
 Hence it may be seen why half-dried marshes, 
 meadows from which a river has retreated in order 
 to return to its bed, great excavations of the soil 
 necessary in railway-cuttings, etc., become the source 
 of a large number of epidemic or contagious diseases. 
 In all these places the subsiding waters have left 
 Schizopkyta, or microbes in a dried state, and these 
 are soon transformed into dormant spores, which are 
 diffused through the air and enter the mouth and 
 lungs of men living near the rivers and marshes, or 
 who are working on the railway-cutting. The soil 
 which has remained undisturbed for a long while is 
 full of dormant spores, drawn into it by the rain to 
 a greater or less depth; these may preserve, their 
 vitality for many years, waiting for the favourable 
 medium which leads to their fresh development. 
 
 An acquaintance with air-germs, with the microbes 
 of earth and water, has therefore become indispensable 
 
THE MICROBES OF HUMAN DISEASES. 159 
 
 to the physician and to the professor of hygiene, who 
 are anxious to decide on the precise cause of great 
 epidemics in order, if possible, to foresee and avert 
 them. This new branch of meteorology has been 
 termed atmospheric micrography, since it necessarily 
 involves the use of the microscope. 
 
 The Microbes of the Atmosphere. In the observa- 
 tory of Montsouris, Paris, there is now a special 
 laboratory under the direction of Miquel, with the 
 object of studying the living organisms of the air, 
 of establishing statistics of their times and seasons, 
 
 Figs 74, 75. Microbes and spores of atmospheric dust, mixed with amorphous 
 particles, and collected by the aeroscope. 
 
 and of drawing general conclusions as to the hygienic 
 condition of the air, according as it is more or 
 less charged with the microbes and spores which 
 are factors of disease. This laboratory is provided 
 with, the apparatus necessary for such kinds of 
 research. 
 
 The first of these apparatus serves to collect the 
 living organisms which are always mingled with a 
 large amount of inert dust (Figs. 74, 75). The 
 
160 MICROBES, FERMENTS, AND MOULDS. 
 
 apparatus is founded on the principle of the aeroscope, 
 invented by Pouchet for the examination of air-dust. 
 It consists of a small cylinder in which a current of 
 air is produced by means of an aspirator, on which 
 running water acts, similar to those in use in all 
 laboratories of physics and chemistry. A thin plate of 
 glass, which has on it a layer of glycerine, is placed 
 at the bottom of the cylinder, so as to intercept the 
 current of air and arrest the dust. The apparatus 
 employed by Miquel at Montsouris is only a modifica- 
 tion and improvement of the one devised by Pouchet. 
 The glass slide is then transferred to the objective 
 of the microscope in order that the dust deposited 
 on it may be examined. 
 
 This process has enabled Miquel to define the laws 
 which rule the appearance of microbes in the atmo- 
 sphere, and he has been able to calculate their number 
 in a given volume of air. With respect to such fungi 
 and algs& as live in our houses (moulds), and on our 
 roofs, walls, and on damp ground (such algae as Peni- 
 cillium, Protococcus, Cklorococcus, etc), he has arrived 
 at the following results, as far as Montsouris, the site 
 of his experiments, is concerned. 
 
 Few in number in January and February, the 
 number of mould-spores further diminishes in March, 
 and rises again in April, May, and June, in which 
 month the maximum is attained. The decrease is slow 
 up to October, more marked in November, and the 
 minimum is observed in December. In this case the 
 
THE MICROBES OF HUMAN DISEASES. 161 
 
 influence of rain and damp is very marked. In winter 
 the average number of spores in every cubic metre of 
 air does not exceed 7000, while in June it rises to 
 35,000. 
 
 In summer, however, when the temperature is 
 very high, the number of spores is not great ; for this 
 reason, that, in spite of the heat, the air is moist, and 
 the spores settle on the ground, plants, or other objects, 
 instead of floating in the air. On the other hand, in 
 winter, since very cold weather is generally dry, the 
 number of air-germs increases. 
 
 In summer, storms only purify the air for a very 
 short time ; within fifteen or eighteen hours after the 
 rain, the germs reappear, and are five to ten times 
 more numerous than before. It seems that storms 
 give an energetic impulse to the production of moulds. 
 
 If we turn to consider microbes, strictly so called, 
 or the bacteria which are the causes of malignant 
 
 O 
 
 diseases, research becomes more difficult, on account 
 of their smaller size and great transparency. An 
 expedient is necessary to reveal their presence and 
 enable us to count them accurately : this expedient 
 consists in staining them by various processes, of 
 which we shall speak when we come to discuss the 
 micrographic study of drinking-water. Miquel prefers 
 the process of filtration of the air invented by 
 Pasteur, which consists in passing the air and aqueous 
 vapour into such sterilized liquids as are favourable 
 
 to the nutrition of microbes. 
 12 
 
162 MICEOBES, FERMENTS, AND MOULDS. 
 
 Sterilized Flasks. Pasteur has shown that air may 
 be deprived of all its germs by being passed through 
 a capillary tube, turned back upon itself. He takes 
 a glass flask and draws out its neck so as to form 
 a long tube, which is bent in different directions 
 (Fig. 76). The prolonged application of heat expels 
 the air contained in the flask, which is therefore 
 sterilized, and it is then allowed to cool slowly. A 
 
 \ 
 
 Fig. 76. Pasteur's flask, with bent tube, containing a culture liquid, sterilized. 
 
 hot culture liquid may now be put into the flask. It 
 must be ascertained, by keeping the flask at a tem- 
 perature of 36 for several days, that the liquid is 
 completely sterilized. The culture flasks are thus 
 fitted to receive the air which is to be the object of 
 study, together with the spores contained in it. 
 
 Culture liquids. There is a considerable variety 
 of culture liquids : Pasteur's mineral solution, infusion 
 of hay or turnips, neutral urine, chicken-broth, beef- 
 tea, etc. They should be plunged in a bath heated 
 to a temperature of 150 to 180, since some spores 
 
THE MICROBES OF HUMAN DISEASES. 163 
 
 are capable of resisting a prolonged boiling at a 
 temperature of 100 ; they still live and are capable 
 of germinating and multiplying when the liquid is 
 cooled. 
 
 Culture liquids may also be sterilized without 
 the use of heat, which to some extent affects their 
 nature, by filtering them through a porous substance 
 biscuit- ware, or a mixture of plaster and amianthus, 
 etc. A more perfect apparatus is employed by Miquel, 
 consisting of a filter of very thick paper, through 
 which the liquid is forced by the simultaneous action 
 of a vacuum on one side, and of strong pressure on 
 the other. 
 
 For the artificial culture of microbes, solid or 
 partially solid substances are by preference often used, 
 such as gelatine, or slices of potatoes, carrots, hard 
 eggs, etc., prepared in different ways and sterilized 
 before use. We cannot here describe in detail all the 
 processes employed and the precautions necessary in 
 order to avoid error. We must content ourselves with 
 giving the results obtained by Miquel. 
 
 There are on an average 80 bacteria in a cubic 
 metre of Montsouris air. A hundred of these bacteria 
 includes 66 Micrococci, 21 Bacteria and 13 Bacilli. 
 In rain water there is a different proportion : 28 
 Micrococci, 9 Bacteria, 63 Bacilli. At the beginning 
 of a thunderstorm, the rain-water includes a consider- 
 able number, about 15 to the cubic centimetre; then 
 the number diminishes, but Miquel states that " after 
 
164 MICROBES, FERMENTS, AND MOULDS. 
 
 two or three days of damp, rainy weather, the rain- 
 water often contains more bacteria than when it began 
 to fall. Since the atmosphere is then excessively pare, 
 it seems that the bacteria are able to live and 
 multiply in the clouds, or else that the clouds, in 
 their passage through space, take up a varying con- 
 tingent of germs." 
 
 The maximum of air-germs is observed in autumn, 
 the minimum in winter; thus, 50 bacteria were counted 
 in December and January, only 33 in February, 105 
 in May, 50 in June, and 170 in October. 
 
 Inversely to what occurs with moulds, the number 
 of bacteria, low in rainy weather, rises when all 
 moisture has disappeared from the surface of the soil. 
 The effect of dryness is greater than that of warmth. 
 This explains the scarcity of bacteria after the great 
 rains of February, April, and June. A long drought 
 is, however, unfavourable to their development. 
 
 Miquel's experiments lead him to conclude that 
 dew, the evaporation from the soil, is never charged 
 with spores. The dry dust in the neighbourhood of 
 inhabited places, and especially of hospitals, is, on the 
 other hand, charged with microbes. In the centre of 
 Paris, for example, in the Hue de Rivoli, there are 
 nine or ten times as many microbes in the atmosphere 
 as in the neighbourhood of the fortifications. In the 
 Montsouris Observatory, south of Paris, the north 
 winds bring many more bacteria than the south winds. 
 The most impure wind comes from the hills of Villette 
 
THE MICROBES OF HUMAN DISEASES. 165 
 
 and Belleville, crowded and populous quarters, in which 
 are also cemeteries and slaughter-houses. 
 
 It has long been established that the air is much 
 purer on high mountains or on the sea, than in plains 
 and in the vicinity of inhabited places. If glass flasks 
 which have been previously sterilized and deprived 
 of air are taken to a great height on the Alps or 
 Pyrenees, and then tilled with air, it will be difficult 
 to detect any microbes, and the few which may be 
 found are possibly brought by the observer. So 
 again, on the top of the Pantheon, a cubic metre of 
 air only contains 28 microbes, while 45 are found in 
 the park of Montsouris, and 462 in the centre of 
 Paris. 
 
 The Microbes of Running and Drinking Water. 
 Water, whatever be its source, contains many more 
 microbes than air. They are even found in spring- 
 water taken from its source, which shows that they 
 exist in the interior of the earth. The following is 
 Miquel's estimate, which will give an idea of the 
 quantity of microbes found in Paris water, taken from 
 different places : 
 
 Source of water. No. of microbes 
 
 to the litre. 
 
 Condensed aqueous vapour ... ... ... 900 
 
 Water from drai ., Asnie.'es 48,000 
 
 Rain-water 64,000 
 
 V; i nne water (Monl rouge basin) 24^,000 
 
 Seine water (from Bercy, above Paris) 4,800,000 
 
 Seine water (from Asn eres, b low Fari-) ... ' ... ... 12.800,000 
 
 Sewer-water (from Clichy) 80,000,000 
 
166 MICROBES, FERMENTS, AND MOULDS. 
 
 These numbers are the minima. The putrefaction 
 of stagnant sewer- water produces germs from which, 
 in a few days, microbes are multiplied by thousands. 
 
 Certes, in France, and Maggi, in Italy, have lately 
 been occupied with the micrographic study of drink- 
 ing-water. These observers reveal the presence of 
 microbes in the water under examination by means 
 of staining reagents. The reagent most in use is a 
 1*5 per cent, solution of osmic acid (Certes). Osmic 
 acid kills the microbes without changing their form, 
 and precipitates them to the bottom of the glass 
 vessel, whence it is easy to collect them. A cubic 
 centimetre of the solution suffices for 30 or 40 cubic 
 centimetres of water. It is allowed to settle, then 
 the liquid is poured off, and the thick, dark-coloured 
 deposit which remains consists of all the organisms 
 previously diffused in the liquid, and may be examined 
 under the microscope. The only drawback to the 
 use of this reagent is the high price of osmic acid, 
 a matter worth consideration in the extensive and 
 comparative researches necessary in these cases. 
 Maggi obtained analogous results with chloride of 
 palladium, and Certes with iodide of glycerine, and 
 alcoholic solutions of cyanine, gentian, etc. ; but none 
 of these reagents are as efficient as osmic acid, of 
 which the effect is more precise, constant, and durable. 
 
 Microbes of the Soil. The presence of microbes in 
 the soil has been proved by Pasteur and his fellow- 
 workers, Chamberland and Roux, in the researches into 
 
THE MICROBES OF HUMAN DISEASES. 167 
 
 the nature of anthrax, of which we have spoken above. 
 These observers collected earth in the neighbourhood of 
 trenches in which animals which had died of anthrax 
 had been buried, a 'id found that not only on the surface, 
 but at some depth, this earth was full of bacteridia 
 (Bacillus anthracis), and also of many other microbes 
 or germs, of which the inoculation might produce more 
 or less dangerous diseases in animals. In order to 
 procure earth in a more perfect state of division, it 
 occurred to Pasteur to collect the excrement of earth- 
 worms, which consists almost exclusively of clay, rich 
 in humus or vegetable earth, on which the worms 
 are nourished. This earth, after passing through the 
 intestinal canal of worms, still contains microbes which 
 have not lost their virulence. As we have already 
 said, spring water, on issuing from the soil, contains 
 microbes which it has acquired in filtering through 
 geological layers; and we have also mentioned the 
 living microbes of chalk, dating, as Bechamp believes, 
 from the secondary epoch. 
 
 Telluric and Diblastic Theories. Hence, it is in- 
 telligible that a theory should have been formed, 
 ascribing most epidemic diseases to the influence of 
 microbes of the soil, which can at a given moment 
 (inter the human body, first by penetrating into the 
 lungs and digestive organs, and thence into the blood. 
 
 Two German discoverers, Pettenkofer and Nageli, 
 set forth this telluric theory of disease, and several 
 facts confirm it. It explains why intermittent fever or 
 
168 MICROBES, FERMENTS, AND MOULDS. 
 
 malaria only prevails in marshy countries when the 
 marshes are partially dry, and especially in summer. 
 In order to make such country healthy, the marshes 
 must be completely dried and filled up, and then 
 transformed into cultivated ground. So, again, the 
 river valleys in France only become unhealthy when 
 the stream returns to its bed, leaving the adjoining 
 meadows transformed into marshes, which gradually 
 dry up and send forth into the air a host of spores, 
 produced by the schizophyta deposited by the water. 
 Finally, great excavations of earth diffuse through the 
 atmosphere the dormant spores brought thither by rain, 
 and remaining in a desiccated state in the soil. 
 
 In many cases, the intervention of two microbes of 
 different kinds have been assumed to explain the nature, 
 and progress of great epidemics, such as cholera, yellow 
 fever, and typhoid fever. This is termed by Nageli the 
 diblastic theory (or that of two producing agents ot 
 disease). Thus the microbe of malaria, or intermittent 
 fever, which is not contagious, often predisposes the 
 patient to receive the attacks of another zymotic 
 disease, such as cholera or typhoid fever. The two 
 microbes may subsist simultaneously in the human 
 frame, and their joint action may weaken the organism 
 at the expense of which they live and multiply. 
 Numerous cases might be cited to support this theory, 
 and the following examples may be given : 
 
 "In the summer and autumn of 1873 the town of 
 Spires was visited by cholera, which was limited to 
 
THE MICROBES OF HUMAN DISEASES. 169 
 
 the lower part of the town, situated on the banks of 
 the Speyerbach. There was a hospital for old men, 
 situated in the high part of the town, a quarter which 
 remained free from cholera, but 24 out of the 200 
 pensioners whom the hospital contained were attacked 
 by the disease. Now 33 of these men, the most able- 
 bodied among them, had been employed to dig up 
 some blighted potatoes in a field which lay very low, 
 almost on a level with the water which had collected 
 in a deserted sand-pit. They had not drunk of the 
 water in this field, neither had they passed through 
 the part of the town visited by the epidemic : 20 out 
 of these 33 men had cholera, and only 4 others out of 
 all the inmates of the hospital contracted the disease" 
 (Nageli). 
 
 Observations made on board Fnglish transports 
 on the voyage from India give analogous results. 
 "Detachments of equal number from two regiments 
 embarked on the same steam transport. A few days 
 later, cholera declared itself and carried off many 
 soldiers, all belonging to one of the two regiments, 
 and coming from a camp in which there was a violent 
 outbreak of cholera shortly after their departure. The 
 detachment from the other regiment, coming from a 
 place exempt from cholera, altogether escaped." Here 
 the influence of the locality and the soil is evident; it 
 was the sole and essential agent of the disease, since 
 the contagion could not have occurred on board ship, 
 in 'vhich the conditions are generally healthy, neither 
 
170 MICROBES, FERMENTS, AND MOULDS 
 
 by contact with the men, nor by that with the 
 clothes and baggage, which were mixed together. 
 The cholera microbe which had been brought on 
 board ship could only act on the detachment mias- 
 matically predisposed by their previous residence in 
 an unhealthy place, containing the malaria microbe 
 (Nageli). 
 
 Miasma and Microbes. This leads us to say a few 
 words on the term miasma, formerly in such common 
 use, and now without meaning. Before the existence 
 of microbes and air-germs was known, the doubtful 
 and mysterious principles which were believed to be 
 the cause of virulent and contagious diseases were 
 termed miasmata, and these miasmata were generally 
 supposed to be gases. It is now proved that this cause 
 resides in solid, living particles, the microbes and their 
 germs: the term miasma is less and less employed, 
 or serves to designate air-germs. When, therefore, 
 Nageli uses the word, he regards it as synonymous 
 with microbes or air-germs. 
 
 The Question of Privies. Hence it follows, that 
 it is erroneous to apply the name of miasmata 
 to true gases, some of which exert an injurious in- 
 fluence on the human system. Such are sulphuretted 
 hydrogen and ammonium sulph-hydrate which arc 
 disengaged from privies, and produce the disease called 
 plomb in the men employed to empty them. These 
 gases are deleterious to microbes as well as to men ; 
 microbes cannot co-exist with them, which is perhaps 
 
THE MICROBES OF HUMAN DISEASES. 171 
 
 the reason why these men seem to enjoy an immunity 
 from most contagious diseases. 
 
 People are too much disposed, when an epidemic 
 is prevalent, to accuse the privies, of which the 
 emanations are, under ordinary circumstances, only 
 offensive to the smell When these places, as well as 
 the sewers, are properly constructed, they present no 
 danger. But it is necessary that there should be 
 a sufficient flow of water in both to cover the solid 
 matter. We know, in fact, that if microbes are present, 
 they only become dangerous when dry enough to float 
 in the air. 
 
 In an epidemic of typhoid fever, for instance, the 
 soiled body and bed linen of the patient are much more 
 dangerous than the privies, in which, however, there 
 is a much larger number of microbes. The linen, 
 therefore, as well as the contaminated rooms and 
 furniture, should be immediately disinfected in the 
 mode prescribed by sanitary authorities. 
 
 The system of directing everything to the sewer, 
 which is now universally applied to large towns, and 
 which has encountered much opposition, is certainly 
 excellent when properly understood and applied. The 
 cesspools, as well as the cemeteries, ought to be as 
 remote as possible from the houses of the living. It 
 is as much opposed io public health to retain cesspools 
 which are gradual!} 7 " filled in the course of years, in 
 the midst of a town, as to have intramural cemeteries. 
 Everything should be carried off by the sewer, pro- 
 
172 MICROBES, FERMENTS, AND MOULDS. 
 
 vided there is a sufficient flow of water to take all 
 solid matters with it and completely cover them. 
 These are deposited in places assigned for them, which 
 must necessarily be very remote from thickly populated 
 places. When these matters are then spread over 
 a large surface to dry in the air, the oxygen becomes, 
 as Pasteur has said, the great purifier of microbes. 
 
 In Paris, some of the sewage water of the great 
 main sewer is diverted on to the peninsula of Genne- 
 villiers, and it is then directed into gutters to serve as 
 a manure for market gardens. After filtering through 
 the cultivated plots, the water flows off in a limpid 
 stream. 
 
 Cornilleau, whose medical practice is at Genne- 
 villiers, has recently issued a report, showing plainly 
 that the sewage is but a slight source of danger to 
 the inhabitants of the peninsula. During the serious 
 outbreak of typhoid fever which occurred in Paris in 
 1882, there were only two typhoid cases in the whole 
 commune, and these cases were imported from Paris. 
 
 II. MICROBES OF THE MOUTH AND DIGESTIVE CANAL 
 IN A HEALTHY MAN. 
 
 Since there is a profusion of microbes in the air, 
 we can easily understand why they should be found 
 in the human mouth, and hence in all parts of the 
 digestive canal. They are for the most part harmless, 
 
THE MICROBES OF HUMAN DISEASES. 173 
 
 as long as the epidermis of the mucous membrane 
 covering the intestinal canal is healthy. Pasteur has 
 shown that they are not found in the blood of a 
 healthy man, but that the slightest lesion of the 
 mucous membrane suffices to introduce them into the 
 circulation.* This fact was proved by experiments 
 made at Pouilly-le-Fort on sheep, inoculated with the 
 anthrax microbe by means of their foocf. The mortality 
 among these animals was notably increased when 
 
 Fl^s. 77, 78.' Spirochrpte buccalis, and S. plicatilis, b (mixed witb Vibrio rugula, 
 a), microbes in mouth of a healthy mail. 
 
 thistles, bearded grain, or sharp-edged leaves were 
 mixed with their food, so as to cause little wounds in 
 their mouths, each of which served as an entrance for 
 microbes. As long as the microbes are few in number, 
 they perish quickly in the blood ; but when the 
 number is considerable, the organism has not the power 
 to destroy them ; they soon compete with the corpuscles 
 of the blood, and the most serious diseases ensue. 
 
 Miquel estimates the number of spores introduced 
 into the human system by respiration, when the health 
 
 * This is not the case with fishes. Kichet and Ollivier have shown 
 that microbes are normally found in the blood of sea-fish, without 
 affecting their health. 
 
174 MICROBES, FERMENTS, AND MOULDS. 
 
 is perfectly sound, at 300,000 a day, and 100,000,000 
 a year. It is evident that these germs, always 
 present, may easily become the source of diseases, of 
 which thrush in the mouth of infants, and of sick and 
 dying adults, is one of the least alarming. 
 
 Sternberg, surgeon of the United States army, 
 1880, writes : " When I was occupied in the micro- 
 
 Fig. 19. Vibrio rugula (Warming) in different stages of development: b, c,f, indi- 
 viduals with vihratile cilia (JlayeHum); /', ciliated spores. Found in the human 
 mouth and intestines. 
 
 scopic examination of foul river water at New Orleans, 
 I used to find in my own mouth almost all the 
 organisms which were present in the putrefying liquid 
 I was examining Bacterium termo, Bacillus subtilis 
 (Fig. 80), Spirillum undulatum,&nd a variety of minute 
 spherical forms and of rods, difficult to classify except 
 under the generic names of Micrococci and Bacteria. 
 Another organism which I have often found in healthy 
 human saliva is a species of Sarcina, perhaps identical 
 with S. ventriculi" 
 
 But the organism most commonly found in the 
 human mouth, which attracts attention from its large 
 
THE MICROBES OF HUMAN DISEASES. 
 
 175 
 
 size and its abundance, is Leptotkrix buccaiis. It is 
 never absent from the rough surface of the tongue 
 or the interstices of the teeth, and even those persons 
 who make a frequent use of the tooth-brush are not 
 exempt from it. In the latter case, however, it only 
 appears in the form of short, scattered rods ; while in 
 
 Fig. W.Ractcri-im (Radllns) subtil is (ZopD. in different stages: A. ciliat'd r ds ; 
 A', F, spores ; G, Zoogloea. In infusions of hay, and in tlie human m.uth (much 
 magnified). 
 
 other cases, the tufted stems of its vigorous growth 
 abound in the saliva, and are often established on the 
 epithelial cells, whence they may be detached by friction. 
 Sternberg compares the human mouth to a culture 
 apparatus, in which the germs of microbes find an even 
 temperature and the moisture necessary for their 
 development naturally provided for them conditions 
 which can only be artificially produced in the 
 laboratory. 
 
176 MICROBES, FERMENTS, AND MOULDS. 
 
 III. THE VIRULENT MICROBE OF HEALTHY HUMAN 
 SALIVA. 
 
 Pasteur and Vulpian in France, and Sternberg in 
 America, discovered almost simultaneously that the 
 human saliva may, under conditions with which we 
 are still imperfectly acquainted, become virulent, and 
 that this virulence is due to the action of a Micrococcus, 
 normally present in the saliva, a microbe quite distinct 
 from that of rabies, of which we have already spoken. 
 
 It is only known that this micrococcus is very 
 common in the saliva of a healthy man, and that in 
 some individuals the saliva is exceptionally virulent. 
 When injected under the skin of healthy rabbits, it 
 produces grave affections, often resulting in the animal's 
 death. These affections are due to the presence of 
 the micrococcus, since the saliva becomes harmless as 
 soon as these organisms are removed from it. 
 
 Sternberg informs us that his own saliva is 
 among those which possess this curious and alarming 
 property. He regards the more abundant nutriment 
 which this microbe finds in the mouths of some 
 persons as the cause of this virulence, since thus its 
 development is more energetic. " In my own case," 
 he writes, "there is a very abundant secretion of 
 saliva. . . . My culture experiments show that this 
 micrococcus multiplies very rapidly, and in virtue of 
 this faculty it has for a certain time the advantage 
 
THE MICROBES OF HUMAN DISEASES. 177 
 
 over Bacterium termo, which appears to be fatal to 
 the former when p.eseit in any number. ... In 
 my culture flasks, a small drop of blood from an in- 
 fected rabbit gave birth within a few hours to such 
 a number of microbes that the liquid contained in the 
 flask was completely filled with them, and it was 
 deprived of the nutriment necessary for any further 
 development/'* 
 
 The exceptional virulence of this microbe must 
 therefore be ascribed to its vital and reproductive 
 energy, and to the rapidity with w^hich it multiplies ; 
 at any rate, until we know more on the subject. 
 
 IV. THE MICROBES OF DENTAL CARTES. 
 
 Miller's recent researches (1884) tend to show that 
 dental caries is chiefly due to the development of one 
 or more species of bacteria. The presence of acids 
 introduced into the mouth, or developed by certain 
 diseases (ulcers, thrush, etc.) which are themselves 
 produced by microbes, appears to be the predisposing 
 cause of this affection. These acids begin by softening 
 the dentine, deprived at some point of its superficial 
 coating of enamel, and through this the bacteria enter. 
 Saliva can be rendered experimentally acid by mixing 
 it for four hours, at a temperature of 20, with sugar 
 and starch (Cornil). Hence the injuriousness of sugar- 
 plum.* and other sweetmeats, long and correctly 
 13 
 
178 MICROBES, FERMENTS, AND MOULDS. 
 
 supposed to be the cause of the early decay of teeth, 
 especially in children who eat them in excess. 
 
 The microbe which Miller has 
 found to be most common in de- 
 cayed teeth is very polymorphic. 
 Microccocus, bacterium, chains and 
 filaments, are only different phases 
 of the same plant, which also pro- 
 duces acid fermentation in the 
 mouth, and the formation of lactic 
 acid. Within the dentine tubules, 
 a section examined under the 
 microscope shows all the inter- 
 mediate stages between the isolated 
 micrococcus and the filaments 
 (Figs. 81, 82). Miller succeeded 
 in producing this disease in sound teeth artificially. 
 
 Fig. 81. Bacterium of dental 
 caries in the dentine tu- 
 bules: a, artificial cades; 
 b, spontaneous caries. 
 
 o 
 
 
 
 
 
 
 
 
 
 
 
 Fig. 82. Bacterium of dental caries : a, 6, different forms obtained in gelatine 
 culture. 
 
 According to his experiments, the best dentifrice for 
 
THE MICROBES OF HUMAN DISEASES. 179 
 
 the destruction of microbes is a solution of corrosive 
 sublimate (mercuric chloride), one part in 1000, which 
 can be further diluted by four parts of pure water. 
 
 V. MICROBES OF INTERMITTENT OR MALARIOUS 
 FEVERS. 
 
 We say microbes in the plural, since it is almost 
 certain that the different types of intermittent fever, 
 tertian, quartan fever, etc., are produced by different 
 microbes ; moreover, it is probable that these microbes 
 vary with the locality. That of intermittent fever 
 in France is probably not the same as that of the 
 malaria, or fever of the Pontine marshes in Italy ; 
 and the African fevers, again, are probably produced 
 by a different organism. 
 
 Intermittent fevers are the first internal diseases 
 of which the vegetable parasitic nature was sus- 
 pected. Before that time we were only acquainted 
 with the parasites of the skin, and with the entozoaria 
 and epizoaria (intestinal worms, lice, acari, etc.), which 
 are animals. In 1 869, Dr. Salisbury, of Cleveland, U.S., 
 entered on researches which led him to the con- 
 clusion that intermittent fever in the marshy valleys 
 of the Ohio and the Mississippi must be ascribed to 
 the presence in the system of a filamentous alga 
 which approximates to the genus Palmella. The 
 spores of this alga are constantly found in the saliva 
 
180 MICROBES, FERMENTS, AND MOULDS. 
 
 of the subjects of intermittent fever. By exposure 
 during the night of little glass plates in marshy 
 meadows, Salisbury was able to collect similar spores, 
 which settled on the lower surface of the glass, and 
 were found floating in the drops of condensed dew.* 
 On passing through these marshes in the evening, 
 there was a peculiar sense of dryness in the throat, 
 and expectoration revealed the presence of spores of 
 Palmella. Finally, earth taken from these marshes 
 was found to be full of the same organisms. 
 
 When the marsh begins to dry up, the spores are 
 produced in abundance, and intermittent fevers occur. 
 Salisbury writes that " in 18(>2, the weather was very 
 wet until about the 1st of July ; but that during 
 July, August, and September, there was hardly a drop 
 of rain. The springs and water-courses were nearly 
 dried up, the marshes and wet grounds also became 
 dry, vegetation was almost completely arrested, and 
 the whole country presented an arid appearance. 
 Shortly after the drought began, intermittent fever 
 made its appearance in all the unhealthy districts, and 
 spread so rapidly during the months of July and 
 August, that it attacked almost every family living 
 on marshy ground. 
 
 " A low, peaty meadow extends along the canal 
 
 * We must repeat what has been said before, that the presence 
 of these spores in the air is quite independent of that of the vapour 
 which constitutes dew ; in other words, the vapour does not transport 
 these spores, which must, on the contrary, be perfectly dry before they 
 can float in the air and settle on any damp object. 
 
THE MICROBES OF HUMAN DISEASES. 181 
 
 to the south-east of the town of Lancaster, and the 
 neighbouring valleys are low and damp. The third 
 quarter of the town, touching on this meadow, and 
 all that part which is not raised from 35 to 40 feet 
 above the level of the meadow, have always been 
 districts in which attacks of intermittent fever are 
 prevalent. Those who live near the marsh are liable 
 to annual attacks of fever from May to November. 
 In August and September these attacks are generally 
 the most severe." 
 
 We said that moisture does not favour the trans- 
 port of microbes and their spores through the air, 
 but the remark does not apply to fogs, in which 
 numerous spores are found. We know that fogs are 
 formed of minute globules of water, which float in 
 the atmosphere, and of which the vapour of our 
 breath, only visible in cold weather, can give us an 
 idea. These globules of water float in the air just as 
 spores and all kinds of dust do, without wetting 
 the spores or running together, since as soon as this 
 occurs, the fog ceases to be ; it is condensed, and falls 
 in the form of more or less fine rain. Salisbury has 
 ascertained that there is a certain connection between 
 fogs and intermittent fevers, and this explains why 
 people are more apt to contract fever in the morning 
 and evening, at which times there is in summer always 
 a fog floating to a varying height above marshy places. 
 In a farm near Lancaster, the farmer and his wife, who 
 slept on the first floor, were attacked by tertian fever, 
 
182 MICKOBES, FERMENTS, AND MOULDS. 
 
 while their seven children, who slept on the second 
 floor, escaped. Salisbury ascertained that there was 
 a fog every morning, rising from a reservoir which 
 had been recently made. This fog reached the house 
 and rose above the first floor, but not as high as the 
 windows of the second floor, and penetrated into the 
 parents' bed-chamber through the open window. This 
 vapour had the same smell as the marsh, which was 
 covered with fever algse (Palmella febrilis), and pro- 
 duced the same feverish dryness in the throat and 
 pharynx. The vapour dispersed soon after sunrise, 
 and before the children had left their chamber. 
 
 Salisbury likewise ascertained the polymorphism 
 of Palmella febrilis, a polymorphism which is con- 
 firmed by the recent observations of the skilful 
 naturalist Zopf, and this fact explains the mode in 
 which an aquatic alga can live in the human blood, 
 in the form of Bacillus or Spirillum. 
 
 Still more recently (1879), marsh fever, or malaria, 
 which is so common in Sicily and in the Roman 
 Campagna, have been studied from the same point 
 of view by Crudeli, Cuboni, Cecci, and others, who 
 ascribe the disease to a vegetable parasite which they 
 call Bacillus malarial. This bacillus is abundantly 
 found in the blood of patients during the period of 
 attack, while during the period of acme which ter- 
 minates each attack only spores are found. The same 
 microscopic organism is found in all the malarious 
 districts of the Eoman Campagna, and it can be 
 
THE MICROBES OF HUMAN DISEASES. 183 
 
 produced in artificial cultures. It is not found in the 
 healthy parts of Lombardy. In the strata of air 
 which float above malarious ground in summer, this 
 microbe is so common that it is found in abundance 
 
 in the sweat of the forehead and 
 
 hands (Fig. 83). 
 
 This organism is not only 
 
 capable of cultivation, but rabbits 
 
 and dogs can be inoculated with 
 Fig. ss.-Maiaria bacillus ^ so as to produce marsh fever 
 
 in them.* The lesions which 
 
 are observed in an autopsy are the same as those in 
 man, showing that the site preferred by the microbe is 
 the spleen and the marrow of the bones. 
 
 The fact that the bacillus and its spores are suc- 
 cessively found in the blood explains the intermittent 
 type of the disease, tertian, quartan, etc., according to 
 the variety of marsh fever. According to its variety, 
 and perhaps to the species of Schizopkytum, the com- 
 plete evolution of the plant sometimes demands 48, 
 sometimes 72 hours, and the access of fever always 
 corresponds with the period of grentesfc activity in 
 the bacillus that which precedes the emission of 
 spores. 
 
 Two military surgeons, Laveran and Richard, 
 
 * It is generally believed in France that animals, and especially 
 herbivora, cannot contract intermittent fever. This upin on is < rro- 
 neous. It is known that in Italy cattle contract this fever when they 
 are not acclimatized to luuibhy district, and that the) are cured by 
 sulphate of (quinine. 
 
184 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 have also observed the parasitic nature of intermittent 
 fever in Algeria. The organism which they have 
 constantly found in the blood of those affected by 
 marsh fever presents several different aspects, but 
 appears especially to attack the red corpuscle of the 
 
 Fig 84. Parasite of intermittent fever (Laveran): A, normal haematin; B, B, corpuscle 
 - No. 1 ; C, corpuscle No. 2, motionless; 1), corpuscle No. 2, containing mobile 
 pigmented grains ; E cor uscle No. 2, provided with mobile filaments ; G, detached 
 mobile filament; H, H, corpuscle No. .'5; I, K, corpuscle No. 2, of small size, 
 red and agglomerated; h, L, liannatins lo which the small corpuscles No. 2 are 
 attached; iM, pigmented leucocytes, their nuclei made visible by carmine. 
 
 blood, in which, according to Laveran's expression, 
 " it is encysted like a weevil in a grain of wheat." 
 
THE MICROBES- OF HUMAN DISEASES. 185 
 
 This observer thinks that it approximates to the 
 algae of the genus Oscillaria * (Fig. 84). 
 
 The different forms taken by this organism are 
 only the successive phases of its development, and 
 have not yet been observed by a competent botanist, 
 who alone can indicate precisely their true nature. 
 At a certain period of its existence the parasite 
 attaches itself to the red corpuscle of the blood, arid 
 is nourished at its expense. The corpuscle turns pale, 
 loses its colouring matter, and disappears, leaving as 
 residue a small grain of pigment, representing the 
 haemoglobin absorbed by the parasite. Two or three 
 mobile filaments arise from the encysted parasite, 
 which resemble vibrios, and move rapidly in the blood 
 as soon as they become detached. Laveran states that 
 he has found the same organism in malaria patients 
 at Rome ; and Richard found them in the blood of 
 a sailor just returned from China, who was suffering 
 from intermittent fever. The use of the microscope 
 permits an accurate diagnosis of this disease. 
 
 The spherical bodies, or the microbe in its encysted 
 form, announce that the attack is imminent, and no 
 time should be lost in administering sulphate of 
 quinine. Richard writes that " the multiplication of 
 these bodies must be extremely rapid. For instance, 
 in tertian fever they are not found in the intervals 
 of the attacks (apyrewia). As the attack approaches, 
 
 * R<fvue Scientijique, April '29, 1882, p. 527; Jauuar 27, 1883, 
 p 113. 
 
186 MICHOBES, FERMENTS, AND MOULDS. 
 
 they appear in increasing numbers, and their maximum 
 corresponds with the beginning of the rise in tempera- 
 ture; from that moment they begin to perish, since 
 the heat of fever is fatal to them, and completely 
 checks their development. This explains the inter- 
 mittent character of the disease. They produce fever, 
 the fever kills them and then subsides ; when apyrexia 
 occurs they multiply again, excite fever, and so on." 
 Thus tl.ere is a successive series of auto-infection by 
 the parasite itself, unless its development is arrested 
 by sulphate of quinine. "The parasites of typhus 
 and typhoid fever are not affected by a temperature 
 of 40, and even of 42, and hence the continuous 
 character of these fevers." 
 
 Cornil has, with some justice, criticized Laveran's 
 description and illustrations of the parasite of marsh 
 fever. It is difficult to recognize in it an organism 
 really belonging to the animal or vegetable kingdom. 
 The form of the filaments which, as he asserts, issue 
 from the so-called encysted bodies, resemble those 
 which Hoffmann has seen and drawn in blood in its 
 normal state, and also in various diseases, and are 
 probably only expansions of extravasated protoplasm 
 in the red corpuscles at a temperature of 40. The 
 encysted bodies are also, according to all appearance, 
 only blood-corpuscles, more or less affected by disease. 
 
 There only remain the pigmented, encysted granules 
 in the red and colourless corpuscles, granules which 
 have been observed by others, and especially by 
 
THE MICROBES OF HUMAN DISEASES. 187 
 
 Marchiafava and Celli. But experiments undertaken 
 to show that these granules are microbes have as yet 
 afforded no certain results. 
 
 In short, Cornil remarks : " Since bacteria are 
 found neither in the internal organs nor in the blood 
 of those who die of intermittent fever, we are tempted 
 to suppose that the virulent agent resides in the sur- 
 face of the mucous membrane for example, in that of 
 the digestive canal ; and that the chemical poisons pro- 
 duced under the influence of these micro-organisms 
 penetrate thence into the blood. They then act on 
 the red corpuscles of the blood." 
 
 Finally, we must remember that many continuous 
 fevers, especially those of hot countries, seem to be 
 complicated by the presence of two parasitic elements, 
 as we have said in describing Nageli's diblastic theory. 
 To the marsh microbe, which comes from the soil, 
 another is added, of which the immediate origin is 
 due either to direct contagion, or to some other telluric 
 or atmospheric local influence. 
 
 VI. RECURRENT FEVER AND YELLOW FEVER, 
 
 We place these two diseases together, simply 
 because they have rarely been observed in France. 
 Recurrent fever, or relapsing typhus, is a disease 
 which has been observed in Germany, Russia, Ireland, 
 and India, in which latter country it is called jungle 
 
188 MICROBES, FERMENTS, AND MOULDS. 
 
 fever. In all these countries poverty, scarcity, and 
 famine appear to be the predisposing causes. In 
 this case, the presence of microbes in the human 
 blood has been established in the clearest and most 
 incontestable way. This discovery was made by 
 Virchow and Obermeier in 1858, but nothing was 
 published on the subject until 1873. 
 
 The symptoms of the disease are very like those 
 of typhoid fever. The microbe, which may always 
 be found in the blood, and which characterizes the 
 disease, is a Spirillum or Spirochcete (S. Obermeieri) ; 
 that is, a filamentous organism, twisted into several 
 spirals, and animated by very lively movements (Fig. 
 51, m, o). These spirilla may be seen moving in 
 thousands among the blood-corpuscles, when these are 
 placed under the objective of the microscope. 
 
 The difficulties experienced by the original 
 observers in their attempts to inoculate man or 
 animals with the disease, and the fact that in some 
 cases the microbes appear to be absent from the 
 blood of affected persons, have thrown some doubt 
 on the relation between the disease and its microbe. 
 This is because the conditions of the existence of 
 this plant in the system were not sufficiently con- 
 sidered. Albrecht has recently shown (1880) that 
 blood which apparently contains no spirilla will, if 
 kept in a culture-flask for some days, protected from 
 air-germs, become full of these organisms at the end 
 of that time, a proof of the pre-existence of the spores 
 
THE MICROBES OF HUMAN DISEASES. 189 
 
 The same observer was able to point out the spores, 
 which are only visible under a magnifying power 
 of 1000 diameters, and which succeed to the spirilla 
 during the remittent period. Moreover, a monkey was 
 successfully inoculated with the disease at Bombay, 
 and after the lapse of five days spirilla were found 
 in the animal's blood. 
 
 Yellow fever has not yet been sufficiently studied 
 in the countries in which it prevails, but there can 
 be no doubt that it is likewise produced by a special 
 schizophytum. Originating, as it appears, in North 
 America, probably in the delta of the Mississippi, this 
 disease has been spread by maritime commerce over 
 the whole intertropical zone of the globe. The centres 
 of infection are always on the sea-board, at the mouths 
 of great rivers, from which we conclude that its special 
 microbe is found in its free state in the brackish 
 marshes formed at river-mouths. 
 
 The medical men of Rio de Janeiro, and particu- 
 larly Freire, have lately described and published illus- 
 trations of microbes said to have been observed by 
 them in the faeces of patients attacked by yellow 
 fever. But their drawings are for the most part 
 fanciful, and betray great inexperience in the methods 
 of research and in microscopic examinations; for 
 instance, the air-bubbles, unskilfully interposed in 
 the preparations which their author thought worthy 
 of photographic reproduction, figure as microbes. 
 Thanks to the accuracy of photography, which leaves 
 
190 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 no scope for the fancy of a draughtsman, there can 
 be no doubt as to the gross error committed by the 
 observer. 
 
 As for Freire's attempts at vaccination, his own 
 statistics are far from being favourable to his method ; 
 in fact, they prove that vaccination increased the 
 rate of deaths in the proportion of 19 per 100. 
 
 Much more scientific researches were undertaken 
 
 Fig. 85. Section of Kidney in yellow fever (Babes'), showing a capillary vessel, c, 
 fill* d with chaplets of micrococci. 
 
 by Cornil in Paris, on some anatomical preparations, 
 preserved in alcohol, which were sent from Brazil. 
 He found in the liver and kidney of the victims of 
 yellow fever, chaplets of micrococci or bacteria (Fig. 
 85), only visible under a very strong magnifying 
 
THE MICROBES OF HUMAN DISEASES. 191 
 
 power (more than 1000 diameters). But they are not 
 invariably present, and it is consequently uncertain 
 whether they are the cause of the disease. From its 
 symptoms and lesions, there is reason to think that 
 the parasite or parasites for there may be several, 
 according to Nageli's theory have their seat in the 
 digestive canal. New and sustained researches, carried 
 on in countries where yellow fever prevails, and more 
 methodically conducted, are necessary to elucidate this 
 question. 
 
 VII. TYPHOID AND TYPHUS FEVERS. 
 
 These two diseases may be taken together, since 
 in both the digestive canal is the part chiefly affected. 
 
 Here crowding, the aggregation of men and the 
 human miasmata resulting from it, play the chief 
 part, admitting, as we have already said, that miasma 
 means microbe. We need not, therefore, deny the in- 
 fluence of predisposing conditions, or what is called 
 receptivity for the disease. These unfavourable con- 
 ditions are: physical exhaustion, bad food, youth, 
 mental emotion all which conditions are allied with 
 human miasmata, the result of crowding in barracks, 
 where typhoid fever prevails; in camps, which are 
 more subject to typhus ; and in the badly built 
 houses of our large cities. 
 
 In few diseases is the influence of anti-hygienic 
 
192 MICROBES, FERMENTS, AND MOULDS. 
 
 conditions more apparent. Want of air and cleanli- 
 ness is one of the principal factors of these cruel 
 epidemics. In the confined lodgings of the artisans 
 of large cities, the dead, the sick, and the healthy 
 man may be found sharing the same room and even 
 the same bed ; linen impregnated with typhoid ex- 
 cretions may remain for days in the same chamber. 
 The walls and Moors of our barracks, too rarely cleansed, 
 disinfected, or whitewashed, harbour myriads of mi- 
 crobes; and the water of adjoining wells likewise con- 
 tains them in great numbers. 
 
 Nor can it be said that hygienic conditions are 
 more carefully observed in the rural habitations of 
 villages and detached farms. The peasant is as 
 ignorant of the laws of health and cleanliness as the 
 artisan; the neglect of the builder, often a mere 
 mason, of the landlord and the tenant, is still more 
 striking in country districts. For this reason epi- 
 demics are generally more fatal in the country than 
 in towns ; but they are less frequent, of shorter dura- 
 tion, and more easily localized in a village or detached 
 farm, since in this case there is a large supply of 
 oxygen, which is the great destroyer of microbes. 
 
 With respect to typhoid fever, one of the most 
 common diseases in this country, the lesions by which 
 it is always characterized show that the microbe pro- 
 ducing it is chiefly found in the mucous membrane of 
 the intestines, in Peyer's glands, and in the isolated 
 follicles which cover this membrane, and which are 
 
THE MICROBES OF HUMAN DISEASES. 193 
 
 always hypertrophied and softened in typhoid patients. 
 The round red spots which may be observed upon the 
 skin are distinctive marks of the affection of the diges- 
 tive canal, and it has occurred to Bouchardat that if, as 
 he supposes, these spots contain the same microbe as that 
 of the intestines, it might be cultivated and attenuated 
 into a true vaccine. 
 
 The presence of special microbes in typhoid fever 
 was first observed by Recklinghausen in 1871, but the 
 exact description of the typhoid bacillus has been only 
 recently given by E berth and Klebs. 
 
 Eberth has observed this bacillus in the spleen, 
 the lymphatic glands, and the intestines, making 
 use of special staining processes. It appears in the 
 form of short rods with rounded extremities, in the 
 tubular glands and round the bottom of these glands, 
 which cover the mucous membrane of the intestine. 
 They are numerous when the ulceration of Peyer's 
 glands begins; afterwards they become fewer, and 
 are succeeded by other microbes. From the position 
 of the bacteria in a section of the mucous membrane, 
 it may be seen that they penetrate through its surface, 
 and fasten on the ulcerated and mortified tissue 
 (Cornil). 
 
 Blood taken from living patients often displays 
 bacilli amid the red corpuscles (Fig. 86). The spleen, 
 which is always hypertrophied, contains the same 
 bacillus, which is also found in the liver, and some- 
 times in the kidneys and urine. 
 14 
 
194 MICROBES, FERMENTS, AND MOULDS. 
 
 Many other bacteria appear in the intestines when 
 the disease is approaching its end, but the bacillus in 
 question is the only one found in the blood and 
 internal organs, so that it is really characteristic of 
 the disease. 
 
 Gati'ky, a German micrographist, and a pupil of 
 Koch, has succeeded in the artificial culture of this 
 microbe, taking it from the spleen of persons who died 
 of typhoid fever. It is actively developed on gelatine 
 and potatoes, becomes very lively and produces endo- 
 
 *^*ro e= /^x 
 
 Fig. 86. Bacilli of typhoid fever (x lf>nn di'tn.): three red corpuscles may be 
 observed in the same preparation. 
 
 genous spores at a temperature of 38. But the inocu- 
 lation of animals with the disease has hitherto been 
 unsuccessful, at least so as to reproduce in them an 
 affection of the intestines, really resembling that of 
 Peyer's glands in man. 
 
 The horse is the only animal affected by a similar 
 disease, which has also been called typhc i 1 fever. In 
 1881, the horses of the Paris Omnibus Company were 
 decimated by an epidemic of this nature. But the 
 Jesion of Peyer's glands cannot be compared with that 
 which occurs in the same glands in man, and no 
 special microbe has yet been discovered. 
 
THE MICROBES OF HUMAN DISEASES. 195 
 
 The presence of the bacillus of typhoid fever in 
 the air or in water has not yet been ascertained. 
 Neither is anything known about the microbe which 
 may be assumed to be the cause of typhus fever. 
 
 VIII. THE CHOLERA MICROBE. 
 
 This terrible disease has its origin in Asia, where 
 its ravages are as great as those of yellow fever in 
 America. It is endemic or permanent in the Ganges 
 delta, whence it generally spreads every year over 
 India. It was not known in Europe until the begin- 
 ning of the century ; but since that time we have had 
 six successive visitations, and it seems destined to 
 replace the plague or black death of the Middle Ages, 
 a disease which appears to be now confined to some 
 few localities of the East.* 
 
 In 1817, there was a violent outbreak of cholera 
 at Jessore, India. Thence it spread to the Malay 
 Islands, and to Bourbon (1819); to China and Persia 
 (1821); to Russia in Europe, and especially to 
 St. Petersburg and Moscow (1830). In the following 
 year it overran Poland, Germany, and England, and 
 first appeared in Paris on January 6, 1832; here it 
 raged until the end of September. 
 
 * See in the Annuaire de iTifmpeutique, 1885, Bouchardat's 
 account of cholera epidemics in Paris, together with remarks on the 
 nature, the parasite, the hygiene, and the treatment of cholera. 
 
196 MICROBES, FERMENTS, AND MOULDS. 
 
 In 1849, the cholera pursued the same route. 
 Coming overland from India through Russia, it 
 appeared in Paris on March 17, and lasted until 
 October. 
 
 In 1853, cholera, again coming by this route, was 
 less fatal in Paris, although it lasted for a longer time 
 from November, 1853, to December, 1854 
 
 The three last epidemics, 1865, 1873, and 1884, 
 differ from the foregoing in not having taken the 
 continental route; they came by the Mediterranean 
 Sea. Brought from India to Egypt by the Mecca 
 pilgrims, the epidemic of 1865 entered France by way 
 of Marseilles, ravaged Provence during the summer 
 of 1865, and was carried to Paris towards the end of 
 September by a woman who came from Marseilles. 
 It was less fatal than the preceding epidemics, and 
 so also was that of 1873. 
 
 The epidemic of 1884 took the same route. First 
 localized in Alexandria (1883), it attacked Naples, 
 Marseilles, and Toulon in the summer of 1884, and 
 overran all Provence; thence it was transferred to 
 Nantes, to several towns in the north-west of France, 
 and to Paris, where it was comparatively mild. Finally, 
 it entered Spain at Barcelona towards the end of the 
 year, and ravaged the whole peninsula through the 
 summer of 1885. In August, it also reappeared in 
 Marseilles and Toulon, and this could not be ascribed 
 to a fresh importation from Spain or the East. 
 
 The essential^ epidemic and contagious progress 
 
THE MICROBES OF HUMAN DISEASES. li>7 
 
 of this disease clearly indicates the presence of a 
 microbe, of which the chosen seat is the intestines, 
 whence it passes with the patient's faeces, and con- 
 stitutes the contagious element in places affected by 
 the epidemic. 
 
 The first precise micrographic researches made on 
 this subject were those of the French and German 
 commissions sent to Alexandria in 1883. Koch, 
 member of the German sanitary commission, was 
 the first to describe the microbe which it has been 
 decided to consider as the producing agent of cholera. 
 He gave it the name of comma bacillus (Bacillus 
 komma), on account of its form. 
 
 In order to see these bacilli in any number, a case 
 of malignant cholera must be observed. For this 
 reason, an unsuccessful search for this parasite has 
 often been made, since it cannot be distinguished from 
 the numerous other parasites found with it in the 
 intestines of cholera patients on the second or third 
 day. A small fragment of the rice-water evacuation 
 of cholera should be placed on a glass slide and 
 stained with methyl violet or methylene blue; the 
 superfluous liquid must be drained off, and the pre- 
 paration may then be examined under a magnifying 
 power of from 1200 to 1500 diameters, making use 
 of an immersion lens, on which light is thrown by an 
 achromatic condenser. 
 
 The comma bacilli then present the appearance 
 shown in Fi. 87, and, in spite of the colouring matter, 
 
198 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 are full of motion and activity, which they retain for 
 some time. They are arched in form, and, roughly 
 speaking, resemble a comma. Their length is 1 J micro- 
 millimetres to 2 J micro-millimetres, and their width is 
 0*6 to 07 micro-millimetre. They are often arranged 
 in chains or chaplets, so as to appear like the letter S, 
 or several S's, placed end, to end as we see in Fig. 87. 
 These latter are the most characteristic. Compared 
 
 Fig. 87. Cholera microbe, or Bacillus Jcomma (Koch): a-z, the different forms which 
 it presents in it growth and division into cells (gr. atly magnified); 1, 2, cultures 
 of bacillus, under a simple lens. 
 
 with the microbe of tuberculosis, that of cholera is 
 shorter and thicker. Its spiral shape has led to the 
 belief that it is an intermediate form between the 
 genera Bacillus and Spirillum. 
 
 Comma-shaped microbes may be found in most 
 stagnant and running water, but they are in general 
 much larger, and none of them present the charac- 
 teristic dimensions of Bacillus komma. 
 
 This bacillus is found in the riziforin grains of 
 choleraic evacuations, which are, as we know, formed 
 
THE MICROBES OF HUMAN DISEASES. 199 
 
 by the desquamation of the mucous membrane of the 
 intestines. The membrane is, in fact, literally flayed 
 from one end to another, and, in consequence of its 
 congestion, the walls of the intestines are of a bright 
 rose colour. The riziform grains consist of small 
 tufts of epithelial cells, conglomerated together, and 
 they contain numerous bacilli. 
 
 They are also found in the glands of the intestine 
 into which they penetrate, owing to tho desquamation 
 of the epithelium. They have not as yet been found 
 in the kidneys, the urine, or the blood. 
 
 Cultures of this microbe on gelatine or gelose are 
 very successful. Koch has observed that it readily 
 multiplies in damp linen, or in miik, broth, eggs, 
 moistened bread, potatoes, etc. The temperature most 
 favourable to it is from 30 to 40, and even at 20 it 
 still multiplies on gelatine. Below 16 it grows very 
 slowly, but does not perish. Cold does not kill it : at 
 10 below zero it is still alive, and capable of resuming 
 all its activity when replaced in favourable conditions. 
 This microbe is aerobic, and soon dies when deprived 
 of air. 
 
 Water can serve as its vehicle, but does not supply 
 sufficient nutriment, so that it soon disappears. 
 This, however, is not the case with stagnant water- 
 containing organic matter. When the level of sub- 
 terranean waters sinks, the surface water becomes 
 more charged with all kinds of refuse, and the 
 multiplication of germs becomes more easy. Bacilli 
 
200 MICROBES, FERMENTS, AND MOULDS. 
 
 cultivated in distilled water die within twelve hours, 
 while they can live for a week in drinking-water. 
 (Cornil.) 
 
 The influence of the level of the subterranean 
 waters on the progress of cholera epidemics was 
 pointed out in Germany by Pettenkofer long before 
 there was any serious idea of regarding a microbe as 
 the cause. 
 
 During his recent travels in India, Koch met with 
 the comma bacillus in the stagnant waters of that 
 country. 
 
 For a long while the attempt failed bo reproduce 
 Asiatic cholera in animals by injections of comma 
 bacilli, and thus to prove the parasitic nature of the 
 disease. The animals in countries attacked by cholera 
 appear to enjoy immunity in this respect. Nicati and 
 Rietsch at Marseilles were, however, successful in pro- 
 ducing cholera by the direct injection of choleraic liquid 
 into the duodenum of guinea-pigs, dogs, etc. Almost 
 all these animals died at the end of two or three days, 
 and the inflamed intestines contained a number of 
 comma bacilli, much more vigorous than those of the 
 injection. 
 
 Lochefontaine, of Paris, swallowed pills which 
 contained choleraic evacuations. He felt unwell for 
 some days, but no serious consequences ensued. It 
 is probable that in this case the acidity of the gastric 
 juice attenuated, or partially destroyed the bacilli. 
 We shall see that acids are, in fact, adverse to the 
 
THE MICROBES OF HUMAN DISEASES. 201 
 
 development of the microbe. Bochefontaine also 
 injected the choleraic virus under the skin of his arm, 
 but the operation was only followed by an osdematous 
 redness, localized round the puncture, and the con- 
 stitutional symptoms were not so marked as those 
 produced by taking the same virus into the digestive 
 canal. 
 
 Ferraris Attempts at Inoculation. This leads us 
 to mention the attempts at inoculation made by 
 Ferran on a large scale in Spain, under the name of 
 anti-cholera vaccinations. 
 
 In 1884, Ferran, a Tortosa physician, was sent by 
 the municipality of Barcelona to study the infectious 
 agent of cholera at Toulon. His preceding studies 
 in micrography pointed him out for this mission. 
 He returned from Toulon, provided with cultures of 
 the comma bacillus, and devoted himself to the 
 study of its life-history. The facts reported by him 
 differ very much from those previously observed, and 
 cannot be accepted without further investigation. 
 
 According to Ferran, the cholera microbe presents 
 a polymorphism which has escaped notice in Koch's 
 investigations, and those of the other micrograph ists 
 who have observed and cultivated it. When trans- 
 ferred to a sterilized alkaline infusion, the comma 
 bacillus increases in length, forms sinuous filaments, 
 then swells at one extremity until it attains to the 
 volume of a red blood-corpuscle, thus constituting 
 an oogoniuin filled with protoplasm. A transparent 
 
202 MICROBES, FERMENTS, AND MOULDS. 
 
 envelope (periplasma) then encloses the oogonium, 
 which thus becomes an oosphere. Close to this, on 
 the original filament, a small swelling appears, which 
 Ferran regards as the pollinidium, or antheridium, 
 which is intended to fertilize the oosphere and trans- 
 form it into an oospore. 
 
 When the rupture of the oospore occurs, the 
 granules contained in it float in the liquid. Those 
 which have been fertilized grow until they are as 
 large as the original oogonium, and constitute mul- 
 berry-shaped bodies, so called on account of the 
 numerous round projections or micrococci which 
 cause the surface to resemble that fruit. 
 
 A very slender filament may soon be seen to issue 
 from one of the points of this mulberry-shaped body, 
 a filament which grows longer, and sometimes two 
 of them appear at once. These filaments become 
 sinuous, twist in spirals, form spirilla, and are then 
 segmented so as to form by fission Koch's comma 
 bacilli, which are the starting-point of the culture, 
 and of this cycle of evolution (Figs. 88, 89, 90). 
 
 Hence it would appear that the cholera microbe 
 must belong to a much higher group than that of 
 bacteria, to which it has been hitherto assigned. 
 This mode of reproduction would show that it is not 
 an alga, but a fungus of the group of Peronosjuorecv, 
 and it is, in fact, termed by Ferran P. Barcinonce 
 while his friends prefer to call it P. Ferrani, after its 
 discoverer. 
 
THE MICROBKS OF HUMAN DISEASES. 
 
 203 
 
 Ferran regards this peronospora as the infectious 
 agent of cholera. Yet it seems extraordinary that 
 such a remarkable polymorphism should have escaped 
 the observation of Koch and of the numerous micro- 
 
 Figs. 88, 89, 90. Evolution of cholera microbe (Pernnospora Ferrawi: Ferran") : 
 1. Cholera microbe (Ilacillus kumma), discovered by Koch. 2. Spiral form of 
 bacillus, transferred from gelatine to an infusion. 3. Degeneration of spiral 
 form after a series of successive cultures. 4. Cholera microbe (Peroiiospora 
 Ferrani): development of oogonium on the spirilla and straight filaments. 
 5. I he oogonium is filled with granules which centre in a point k, and it is then 
 converted into an oosphere ; m, poilinidiuiu on fertilizing o gan 6. The oospuere 
 is converted into mulberry-shaped and comma-shaped bodies. 
 
 graphists who have made various cultures of the 
 comma bacillus. It is difficult not to suppose that 
 some negligence or error has vitiated Ferran's re- 
 
204 MJCKOUES, FERMENTS, AND MOULDS. 
 
 searches, and the first idea which will occur to any 
 unprejudiced micrographist, is that P. Fcrrani is not 
 really Koch's comma bacillus, and consequently not 
 the cholera microbe.* 
 
 We have, in fact, already shown that numerous 
 comma-shaped bacteria, or free cells, are found in 
 water and in the human body, and that these may 
 be easily confounded with the true comma bacillus 
 when staining reagents and a very precise mode of 
 culture are not employed. Ferran himself states that 
 this staining process must not be used in the culture 
 of P. Ferrani. Cornil has, however, shown that the 
 true comma bacillus is not destroyed by methyl 
 violet. Finkler had previously discovered in cholera 
 nostras, which is not epidemic, a comma-shaped 
 microbe resembling in many respects the one 
 described by Ferran. Koch has shown that this 
 microbe, as well as one of similar form found by 
 Lewis in the saliva, does not act in cultures like the 
 microbe of Asiatic cholera; Lewis's microbe does not, 
 like the cholera bacillus, liquefy gelatine. 
 
 The precautions necessary for the sowings of 
 culture liquids are so great that we may be permitted 
 to doubt whether Ferran has always guarded against 
 error. Brouardel's report shows, after a visit to 
 
 * Our criticism on the description and illustrations of Laveran's 
 marsh-fever microbe might be applied, word for wor I, to Ferran 's 
 description and illustrations of the cholera microbe, which wo have 
 reproduced above. 
 
THE MICROBKS OF HUMAN DISEASES. 205 
 
 Ferrari's laboratory, that the instruments and methods 
 in use there were primitive and insufficient. 
 
 Until these facts have been confirmed by other 
 observers, it seems prudent to regard P. Ferrani and 
 B. komma as two absolutely distinct microbes. It 
 does not follow that the culture liquids employed by 
 Ferran did not contain the latter, but it is probable 
 that it also contained, and in larger numbers, a second 
 microbe (?), which is Ptronospora Ferrani. 
 
 It may also be observed, the injection of Ferran's 
 culture liquid into the intestines of guinea-pigs pro- 
 duced no effect, while subcutaneous injections soon 
 killed these animals and distinctly affected men. This 
 is precisely the opposite effect to that observed by 
 Nicati and Rietsch at Marseilles, and by Bochefontaine 
 in Paris. 
 
 This is a crucial difference, since it shows that 
 the two microbes are not identical, and all our know- 
 ledge of cholera tends to show that its microbe has 
 a special action on the intestines.* 
 
 However this may be, Ferran carried on his 
 culture experiments in the endeavour to obtain an 
 attenuated microbe which might serve for preventive 
 inoculations. He believes that he has succeeded, and 
 
 * The experiments made by Gibier and Van Ermengen in August, 
 1885, confirm th : s opinion. After inoculating a certain number of 
 guinea-pigs, according to Ferran's hypodermic nuthoJ, with a virulent 
 culture liquid, and giving them time to recover, the same liquid was 
 injected into the stomach of these animals, and they all died with the 
 symptoms and lesions of cholera 
 
206 MICROBES, FERMENTS, AND MOULDS. 
 
 after inoculating himself, he performed the same 
 operation on several of his friends ; then on thousands 
 of people in different towns of the province of Barce- 
 lona, and throughout Spain. 
 
 His inoculation consists in introducing, by means 
 of the small syringe used for hypodermic injection, 
 about a cubic centimetre of the vaccinal liquid, the 
 nature of which is kept secret by its author. There 
 is always a certain discomfort after the operation, 
 but it disappears at the end of a few hours. Ferran 
 himself states that one inoculation will not suffice 
 to ward off the contagion. A second, third, and even 
 more, are necessary for the attainment of this object, 
 but the discomfort caused by the operation always 
 becomes less. 
 
 Up to this time the results obtained by the pro- 
 cess during the recent epidemic in Spain are not 
 accurately known, since Ferran has been unable to 
 produce the official statistics which are necessary to 
 confirm his assertions. 
 
 We are, therefore, entitled to reserve our judg- 
 ment, both as to the value claimed for this vac- 
 cination, and as to the true nature of the microbe 
 cultivated by Ferran, and considered by him to be 
 the infecting agent of cholera. If, again, we recur 
 to the facts established by Bochefontaine, it may be 
 asked whether subcutaneous injection is the true 
 mode of inoculation applicable to this disease, and 
 if the process adopted by Bochefontaine, of intro- 
 
THE MICROBES OF HUMAN DISEASES. 207 
 
 ducing the attenuated microbe into the stomach by 
 means of pills or a liquid, would not be more rational. 
 
 Mode of Propagation and Persistence of Cholera. 
 The upper part of the delta of the Ganges seems to 
 be the original home of cholera and its microbe. 
 Below this region, the stagnant water on each side 
 of the river, infected with every species of ordure, 
 renders the maritime base of the delta wholly unin- 
 habitable. But even in its upper part the land is 
 nearly covered by water. In order to build a house, 
 the earth is heaped up to raise the level of the soil, 
 and the house stands on the embankment, surrounded 
 by water. A high temperature is necessary to enable 
 the bacillus to live in water, and it is probable that it 
 will never become acclimatized in our colder climate. 
 The drainage which has been carried on round Cal- 
 cutta has already rendered epidemics less serious. 
 
 The disease is always propagated by man. In 
 India, Arabia, and Egypt, its diffusion is chiefly owing 
 to pilgrimages. In Bengal the pilgrims all bathe 
 together in sacred pools, often only a few square 
 metres in size, and receiving some thousands of men 
 in the course of the day, streaming with sweat and 
 exhausted by long journeys and insufficient food, and 
 under such conditions cholera is often developed. 
 From India it passes to Arabia by means of the 
 Mussulman pilgrims, whose caravans block the nar- 
 row streets of Mecca every year, and thence it is trans- 
 ported to Egypt. Finally, it is carried from Alexandria 
 
208 MICROBES, FERMENTS, AND MOULDS 
 
 to Marseilles and other Mediterranean ports by vessels 
 which have served for the transport of pilgrims, by 
 men, their linen, and other garments. 
 
 It is consequently by the human body and its 
 clothing, or by the water which carries away human 
 fseces or has served for the washing of soiled linen, 
 that the infecting microbes are carried. The air, as 
 it has long been known, need not be taken into 
 account. As early as 1832, it was observed that the 
 wind did not affect the epidemic, which seemed rather 
 to advance like a man travelling by short stages. 
 
 Duclaux's recent researches show that the sun 
 and air attenuate and soon destroy the microbes, and 
 that only dead germs are borne on the air and wind. 
 "In order to retain their virulence unimpaired, the 
 microbes must travel in packages of clothing, in bales 
 of merchandise, or in the close, moist hold of a vessel. 
 In a word, of all agents of sanitation, the sun is at 
 once the most universal, the most economical, and 
 the most active to which the guardians of public 
 and private hygiene can have recourse " (Duclaux). 
 
 Koch has declared that acids in general are the 
 greatest hindrance to the development of the cholera 
 bacillus. In this way, the acid of the gastric j uice 
 is the best safeguard, and many cases of contagion 
 may be explained by the fact that the large quantity 
 of water imbibed has diluted the gastric juice to 
 excess, or else that the source of contagion has 
 rapidly passed through the empty stomach, and 
 
THE MICROBES OF HUMAN DISEASES. 209 
 
 has carried a liquid containing dangerous microbes 
 straight into the intestines. Indigestion, and catarrh 
 of the stomach and intestines, of which diarrhoea is 
 a symptom, constitute predisposing causes of the 
 disease. 
 
 Among other substances . unfavourable to the de- 
 velopment of the microbe, and thus constituting a 
 preventive of cholera up to a certain stage, we may 
 mention calcium sulphate, which acts by producing 
 sulphuretted hydrogen gas, also carbolic acid, salicylic 
 acid, thymol, alcohol, acetic acid or vinegar, and 
 mustard oil, which, like the other volatile substances 
 already mentioned, constitutes an excellent antiseptic 
 in an epidemic of cholera. . 
 
 We shall speak in another chapter of the purity 
 of drinking-water, which is of great importance, and 
 of the improved filters invented to eliminate the 
 microbes which are not arrested by ordinary filters. 
 
 IX. THE EXANTHEMATA : SCARLATINA, SMALL-POX, 
 MEASLES, VACCINIA. 
 
 Microbes are found in the eruptions characteristic 
 of all these diseases. They are generally micrococci, 
 isolated or in chaplets. 
 
 Measles. Babes, in 1880, was the first to describe 
 the micrococci which he observed in this disease, and 
 especially in the pneumonia by which it is often com- 
 15 
 
210 MICROBES, FERMENTS, AND MOULDS. 
 
 plicated. The blood of the eruption, the catarrhal 
 secretion of the nose, etc., contain small round 
 bodies, isolated or in pairs (in the form of the figure 
 8), or more rarely in short chaplets. When there is 
 decided pneumonia, the pulmonary alveoli likewise 
 contain isolated bacteria, in the form of an 8, in 
 chaplets, and even in zoogloea, or massed together. 
 Babes has not yet cultivated nor tried to inoculate 
 this microbe. 
 
 More recently, in January, 1883, Le Bel observed, 
 in the urine of persons attacked by measles, the 
 appearance of slightly curved rods (bacillus) capable 
 of very slow movements. Their length varies con- 
 siderably, and the spores appear in a swelling which 
 occurs at about a third of the length of each rod. 
 This microbe appears for a few days at the beginning 
 of the fever, and disappears with the fever, to return 
 afresh at the moment when peeling begins. We know 
 that these are the two epochs of contagion. The 
 microbe is found in this scurf, and may be obtained 
 by scraping the skin with a knife. Le Bel succeeded 
 in cultivating it in sterilized urine. In serious cases 
 of measles, the microbe remains upon the skin and in 
 the urine for weeks, and even months. It is probable 
 that Babes's micrococcus and Le Bel's bacillus are only 
 two forms of the same microbe. 
 
 Scarlatina. Pohl has found, in the desquamating 
 epidermic cells of this disease, and on the soft palate, 
 microcoeci of somewhat smaller size than those of 
 
THE MICKOBES OF HUMAN DISEASES. 211 
 
 measles. A bacterium in the form of an 8 has also 
 been found in the urine of scarlet-fever patients. 
 
 Stickler believes that he has discovered a vaccine 
 for scarlatina, by passing its virus through the horse 
 or the cow. When these animals are inoculated with 
 the blood of a man suffering from the disease, an 
 eruption accompanied by desquamation occurs three 
 days after inoculation. A man inoculated with this 
 desquamation displayed a rash resembling that of 
 scarlatina, and when the same man was afterwards 
 inoculated with human scarlatina, he did not take the 
 disease. 
 
 Small-pox and Vaccinia. We find in small-pox 
 pustules micrococci, either isolated or united, which 
 may be seen on a section of the skin if they are 
 coloured with methyl violet. The same microbe may 
 be observed on the pustules of the mucous membrane 
 of the larynx, in the liver, the kidneys, and the blood 
 of the vena portse. The attempt to cultivate it has 
 hitherto failed. 
 
 The micrococcus found in small-pox pustules does 
 not differ in its form from that of cow-pox in cows, 
 which constitutes, as we know, the original source 
 of human vaccine. It is not yet certain that the 
 microbes of small-pox and vaccinia are identical, but 
 from the resemblance of the pustules and of the micro- 
 cocci contained in them, it is most probable that this 
 is the case, and this would explain why vaccine is 
 efficacious as a preventive of small-pox. 
 
212 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 It may be useful to retrace here the curious history 
 of vaccine, since it is directly interesting to us all 
 
 
 'A 
 
 Pig. 91 Section of skin covering a small-pox pustule, a, horny layer of the 
 epidermis ; d, adenoid tissue ; w, m, micrococci stained with methyl violet ( x 
 850 diam.)- 
 
 Before vaccine was discovered, inoculation with 
 small -pox was practised as a preventive measure. 
 
THE MICROBES OF HUMAN DISEASES. 213 
 
 This inoculation was known to the Arabs and Chinese 
 as early as the tenth century, but it was decried by 
 physicians, and only practised by women. In India 
 it was practised by the Brahmins, and a public crier 
 announced that he had small-pox virus to sell. 
 
 In 1717, Lady Mary Wortley Montague, wife of 
 the English Ambassador in Constantinople, chanced 
 to see the operation performed by an old Thessalian 
 woman, who always accompanied the puncture with 
 practices of witchcraft and superstitious usages. She 
 asserted that the Virgin herself had appeared to reveal 
 the pecret to her, and boasted of having performed 
 inoculation in more than 40,000 cases. Lady Mary 
 was so much impressed by the results obtained that 
 she had her son inoculated, and it is said that the old 
 Thessalian handled her rusty needle so unskilfully 
 that Maitland, the physician attached to the embass}% 
 was obliged to finish the operation. On her return to 
 England, Lady Mary made the success of the experi- 
 ment generally known. George I. authorized the 
 inoculation of six prisoners in Newgate, and then of 
 six orphans. The operation was performed by Mait- 
 land and crowned with success, and he was then 
 allowed to inoculate members of the royal family, 
 and more than 200 other persons. 
 
 The practice was, however, condemned by the 
 clergy, who considered it to be immoral and anti- 
 religious, as being opposed to the divine rights and 
 will. Some failures, such as the death of Lord Sunder- 
 
214 MICROBES, FEBMENTS, AND MOULDS. 
 
 land's son, awakened alarm, and caused inoculation to 
 be discredited. 
 
 Notwithstanding this, it was introduced into France 
 in 1723 by De La Costa, and accepted by Chirac, 
 Helvetius, and by other physicians of the day. 
 Although opposed by the majority, and officially con- 
 demned by a decree of the Sorbonne in 1753, as "un- 
 lawful and contrary to the law of God " a decree 
 officially confirmed by the faculty of medicine in 1763 
 inoculation continued to be practised up to the 
 time when vaccination was substituted for it. 
 
 Vaccination appears to have been practised in 
 Asia in earlier times. However this may be, it was 
 known in the south of France that farm servants who 
 had been affected by cow-pox were secured against 
 small-pox. These pustules generally occur on the 
 udder, and the milkers were inoculated with the 
 vaccine matter, through some accidental scratch on 
 their hands. Rabault, a Frenchman, communicated 
 this fact in 1798 to Pew, an English physician and 
 a friend of Jenner. To Jenner we must assign the 
 merit of understanding the importance of this fact, 
 and deducing from it one of the most admirable dis- 
 coveries of modern medicine, the preventive method 
 which continually tends to become more general, and 
 to be extended to other diseases, especially since 
 Pasteur's late researches into vaccination for anthrax 
 and for fowl-cholera. 
 
 Pasteur has also shown that the microbes are the 
 
THE MICROBES OF HUMAN DISEASES. 215 
 
 active principle of the vaccine virus. The liquid need 
 only be deprived by filtration of its micrococci in 
 order to become inert, and consequently unfit for use 
 in vaccination. 
 
 X. THE MICROBES OF CROUP AND WHOOPING-COUGH. 
 
 The parasitic nature of croup and diphtheria, which 
 had long been suspected, was only shown in 1881 
 by the researches of two American physicians, Wood 
 and Formad. In the spring of that year a very 
 serious epidemic of croup occurred at Ludington, a 
 small town on the borders of Lake Michigan. Here 
 the principal industry is derived from the neighbouring 
 forests, the trees of which are sawn into planks in the 
 numerous saw-pits, and thus employ almost the whole 
 working population. The town stands on a height, 
 with the exception of one quarter of it, which is built 
 on very low, marshy ground, partly filled up with saw- 
 dust. Here the soil is so wet that when a small hole 
 is dug, it fills with water immediately, and cellars are 
 almost unknown. It was in this quarter that the 
 epidemic was sd severe ; almost all the children were 
 attacked by it, and a third of them had already died. 
 
 Formad went to Ludington to study the epidemic 
 and collect materials for experiments. In all these 
 cases of croup, the blood was full of micrococci belong- 
 ing to Micrococcus diphthericiis, some detached, others 
 
216 MICROBES, FERMENTS, AND MOULDS. 
 
 united in the form of zoogloea, that is agglutinated in 
 small masses ; others, again, in the colourless corpuscles 
 of the blood. All the organs, and especially the 
 kidneys, were likewise filled with them. 
 
 With the materials gathered at Ludington, Wood 
 and Formad made some experiments in cultures, and 
 were able to inoculate rabbits with croup. These 
 inoculations were made subcutaneously, in the muscles 
 and trachea, and were followed by the production of 
 false membranes, and the animals died with all the 
 symptoms of diphtheria. The blood was full of micro- 
 cocci. An examination of living animals showed that 
 the micrococcus first attacked the colourless corpuscles, 
 within which their vibratile motion could be observed. 
 The corpuscle changed in appearance, the granules dis- 
 appeared, and it became so full of rnicrococci that they 
 could no longer move : they grew until they caused the 
 rupture of the corpuscle, and then escaped in the form 
 of an irregular mass, which constitutes the zoogloea. 
 Corpuscles filled with micrococci were found in the 
 false membrane ; in the small vessels, which they dilate 
 and completely obliterate ; and even in the marrow of 
 the bones. 
 
 Cultures made in flasks afforded important results. 
 A comparison of the sowings made with micrococci 
 collected at Ludington with those found in the 
 ordinary diphtheritic angina, which is common at Phila- 
 delphia, showed a great difference in the vitality and 
 virulent properties of microbes derived from these two 
 
THE MICROBES OF HUMAN DISEASES. 217 
 
 sources. The former multiplied rapidly and energeti- 
 cally, succeeding each other up to the tenth generation, 
 while those from Philadelphia only went to the fourth 
 or fifth generation, and those taken from the tongue 
 did not go beyond the third. It must be observed that 
 the diphtheritic angina of Philadelphia is much less 
 fatal than croup, and the first attempts at inoculation 
 made by Formad and Wood produced doubtful results, 
 precisely because they were made with the microbe 
 of diphtheritic angina, which is an attenuated form 
 of the microbe of croup. The organism is the same, 
 but it is modified by the medium in which it is 
 developed, and the vitality of artificial cultures is in 
 direct proportion to the malignity of the disease from 
 which the germs for sowings are derived. 
 
 The following theory may be deduced from these 
 facts, which will explain all cases of diphtheria : A 
 child contracts a simple catarrh al angina, or laryngitis ; 
 the micrococci, which up to this time remained inert 
 in the mouth, begin to grow and multiply under the 
 influence of the inflammatory products which favour 
 their development ; the plant which has been dormant 
 becomes widely diffused. There are many degrees 
 between croup with malignant complications and the 
 mildest form of diphtheritic angina, as all practical 
 physicians know. More or less numerous germs of 
 micrococci float in the air, or which appeared to be 
 the case at Ludington are conveyed in drinking- 
 water, and they may encounter more or less favourable 
 
218 MICROBES, FERMENTS, AND MOULDS. 
 
 conditions. If they settle on a child's tender throat 
 predisposed for their reception by slight inflammation, 
 they develop there with frightful rapidity, and 
 produce croup, and then diphtheria, which is soon 
 fatal. Nageli calculates that their number may be 
 doubled within twenty minutes. The plant, of which 
 the activity is increased by its culture in the person of 
 one patient, may be expelled with the breath so as 
 to infect another individual. And just as there are 
 different degrees of activity in the plant, so the spores 
 may be more or less contagious, and those of malig- 
 nant diphtheria are more to be feared than those of 
 the ordinary diphtheritic angina. 
 
 When we consider the remedies to be employed 
 against the ravages of this cruel disease, it should 
 first be observed that the only effect of the operation 
 of tracheotomy, which is successful in barely a third 
 of the cases, is to admit air into the child's lungs. 
 Its first curative effect, therefore, consists in saving the 
 child from the asphyxia by which it is threatened, 
 and in giving time to apply remedies, but another 
 explanation is necessary when this operation alone is 
 enough to effect a cure. Pasteur has shown that pro- 
 longed contact with the air produces a real attenuation 
 of virulent microbes. Wood and Formad have estab- 
 lished similar facts, for when the false membranes of 
 croup procured at Ludington had been exposed to the 
 air for several weeks, until they were completely 
 desiccated, they became perfectly inert, notwith stand- 
 
Of THl 
 
 "C^ 
 
 THE MICROBES OF HUMAN i)i^Q$yM 219 
 
 ing their former virulence. They were, however, not 
 dead, since they were still capable of reproduction, but 
 only up to the third or fourth generation. It must, 
 therefore, be admitted that the free access of air given 
 by tracheotomy, may attenuate the virulence of the 
 micrococcus of croup. 
 
 Too much cannot be said against the misuse of 
 emetics, which is, unfortunately, very common, since they 
 are readily administered by parents without medical 
 advice. A regular emetic of which the action is 
 much more violent than that of ipecacuanha should 
 never be given. The micrococci are only found in 
 the most superficial layers of the false membranes, 
 and when these are removed, an irritated and bleeding 
 mucous membrane remains, which had been previously 
 protected by the false membrane from immediate 
 contact with the microbes : these now pass without 
 difficulty into the blood. Thus the ground may be 
 said to be prepared and rendered more favourable 
 for the multiplication of the micrococci, which are 
 sown there afresh, and are reproduced with frightful 
 rapidity. 
 
 The most effectual remedy ha-s been prescribed by 
 Dr. Fontaine of Bar-sur-Seine. It consists in admin- 
 istering sulphurous drugs, in the form of sulphate 
 of calcium, so as to produce in the stomach a 
 slow disengagement of sulphuretted hydrogen gas, 
 which checks the development of microbes, or attenu- 
 ates their virulence. It need scarcely be said that 
 
220 MICROBES, FERMENTS, AND MOULDS. 
 
 this treatment must begin at once, before the micro- 
 cocci have penetrated into the blood. At the same 
 time a gargle of lemon-juice or citric acid should be 
 used, which shrivels up the false membranes without 
 forcibly detaching them. The action of this acid is 
 explained by the fact that, for the most part, microbes 
 only thrive in an alkaline medium. By this treat- 
 ment Fontaine has been able to save nine-tenths of 
 his patients, while all other modes of treatment 
 have only succeeded in a third of the cases, and the 
 proportion is often much smaller. 
 
 The first researches made in Europe on the 
 microbe of diphtheria date from 1873, at which time 
 Klebs gave an exact description of it under the 
 name Microsporon diphtericum. In most cases he 
 observed two forms : micrococci and rods or bacilli. 
 Struck by the great difference in intensity which the 
 disease presents in different epidemics, he states in 
 his later works that there are two kinds of diphtheria, 
 due to the predominance of one or other of these two 
 forms, one of which he terms microsporine, and the 
 other bacillary. The former may be observed in the 
 east of Europe, and especially in Hungary; while 
 the latter is more common in Switzerland and the 
 west, including France. The first is chiefly found 
 upon the tonsils, and is less serious; while the bacillary 
 form soon attacks the larynx and trachea, and pro- 
 duces blood-poisoning, which is rapidly fatal. The 
 bacilli which are, like those of tuberculosis, very 
 
THE MICKOBES OF HUMAN DISEASES. 221 
 
 minute, remain on the surface of the false membranes, 
 more rarely within them, and on the surface of the 
 inflamed mucous membrane. 
 
 Loffler undertook experiments in culture and 
 inoculation which confirm Klebs' opinion. He suc- 
 ceeded in isolating and cultivating separately the 
 Microsporon, or micrococcus, and the bacillus, which 
 makes it probable that these are two distinct species. 
 The chaplets of micrococci, cultivated separately and 
 used to inoculate animals, do not produce diphtheria ; 
 the bacilli, on the other hand, cause the formation of 
 false membranes, but do not exactly reproduce the 
 diphtheria of the human subject. 
 
 Cornil and Babes have likewise studied these two 
 forms of microbes. They have ascertained that the 
 bacilli are more generally found in the false mem- 
 branes of the skin, and the micrococci in those of the 
 throat and larynx. But in almost all cases they have 
 found bacilli, zoogloea, and chaplets of micrococci 
 associated together in the false membranes, even in 
 those of the skin, and bacilli in those of the throat. 
 
 Cornil and Megnin have studied the spontaneous 
 diphtheria of poultry and domestic quadrupeds. The 
 anatomical lesions and the form of the microbes 
 approximate to those of human diphtheria, and cases 
 of contagion between the calf and man have been 
 observed. Yet direct inoculation has failed, so that it 
 is still impossible to affirm the identity of the two 
 diseases. 
 
222 MICROBES, FERMENTS, AND MOULDS. 
 
 We do not think that the dual nature of human 
 diphtheria, indicated by the researches of Klebs and 
 Loffler, is yet established. The symptoms, and still 
 more the histological lesions of this disease, are in 
 favour of its unity, and it may be owing to other 
 causes that the disease is more or less severe. 
 
 The well-known polymorphism of microbes leads 
 us to think that the bacilli represent the adult form, 
 and the inicrococci, or Microsporon, the early form of 
 a single species, which is in all cases the cause of 
 diphtheria and of its several manifestations croup, 
 diphtheria, etc. Further researches are necessary to 
 decide this question. 
 
 Whooping-cough and Influenza. Burger has 
 lately discovered rods in the form of an 8 in the 
 sputum of whooping-cough; they are found in 'great 
 numbers in the white scum, and are even visible to 
 the naked eye, and, like many other bacteria, they 
 can be stained by methyl violet. To this microbe 
 whooping-cough and its relapses are due, and it is 
 always present. It has not yet been cultivated. 
 
 Influenza resembles whooping-cough in the course 
 it takes, and is probably also caused by microbes. 
 Letzerich has found micrococci in the blood, to which 
 he ascribes this disease, but his researches must be 
 repeated with greater care. 
 
 Certain facts observed in medical practice have 
 led to the surmise that whooping-cough may be re- 
 garded as an attenuated form of croup, just as vaccinia 
 
THE MICROBES OF HUMAN DISEASES. 223 
 
 is an attenuated form of small-pox. The same treat- 
 ment applies to both diseases. When the patient is 
 kept in the purifying chamber of a gas manufactory, 
 where there is a constant disengagement of acid 
 vapours, sulphuretted hydrogen, hydro-carbons, coal 
 tar, benzine, carbolic acid, etc., the microbes embedded 
 in the throat and lungs are attenuated. Sulphate of 
 calcium is a successful remedy in whooping-cough as 
 well as in croup. 
 
 Children who have had whooping-cough, or who 
 are passing through the disease, rarely contract croup 
 even when it is epidemic, although catarrh, inflamma- 
 tion of the bronchial tubes, ulceration of the mouth, 
 and general debility, are all predisposing causes of 
 croup. The question therefore arises whether whoop- 
 ing-cough does not act as a sort of preventive vaccina- 
 tion which may serve as a protection against croup. 
 Further researches and observations should be made 
 in this direction, if that which we now indicate can 
 be established as a fact. 
 
 XI. THE MICROBES OF PHTHISIS AND OF LEPROSY. 
 
 These two microbes are so similar in form that it 
 is necessary to have recourse to chemical reagents and 
 to staining processes in order to distinguish them 
 clearly. Both assume the form of an 8, or of slender, 
 elongated rods, so minute that it is not surprising 
 
224 MICROBES, FERMENTS, AND MOULDS. 
 
 that the bacillus should have so long eluded the 
 observation of the physiologists who have studied the 
 tubercle of phthisis under the microscope. The form 
 of both microbes assigns them to the genus bacillus. 
 
 The experiments of Villemin, begun ten or twelve 
 years ago, first showed the parasitic nature of tuber- 
 culosis, or pulmonary phthisis. Villemin inoculated 
 rabbits with tubercular matter, showing that the 
 disease was essentially contagious. More recently 
 Toussaint and Koch have cultivated the microbe in 
 a closed vessel, and have inoculated animals with the 
 produce of the culture ; all these animals died with 
 symptoms of tuberculosis. 
 
 The still more recent researches of Cornil, as he 
 stated in May, 1883, before the Academy of Medicine, 
 have confirmed the parasitic nature of this terrible 
 disease. The microbe has been found in the giant 
 cells of the tubercle and in the sputum of consumptive 
 patients ; it has been found in the colourless corpuscles 
 of the blood, by which it is conveyed into all parts of 
 the system, and it is also found in all the organs in 
 which a tubercle can be developed. 
 
 The bacillus of tuberculosis is somewhat smaller 
 than that of leprosy. Each bacillus is from three to 
 four micro-millimetres in length. They are generally 
 found associated in the form of chains or chaplets at 
 any rate, this is the case in the sputum, as we see in 
 Fig. 91 A. Koch has cultivated them in gelatinized 
 blood-serum. Their growth is very slow. 
 
THE MICROBES OF HUMAN DISEASES. 
 
 225 
 
 Now that this is known, it is easy to explain the 
 facts of direct contagion which are so frequent among 
 people living together, and especially from a husband 
 to a wife, or conversely. Since the breath of a con- 
 sumptive patient is always charged with germs of 
 the microbe, which abound in the cavities in which 
 
 .%-'- 
 
 Fig. 91 A. Bac'lli in U:e sputum of a consumptive patient : A. bacilli, either isolated 
 (a) or in the epithelial (t>) and pigmented (c) cells of the lung; B, numerous 
 bacilli, mas-ed together in the sputum. Stained by Ehrlich s process \\itb 
 methyl violet (much enlarged). 
 
 the sputum is formed, it could not possibly be other- 
 wise. The following statements of facts are taken from 
 Debove's clinical lectures at the Hospital de la Pitie. 
 
 " Jean, a tuberculous patient, was married to 
 Antoinette, a young woman with no previous tendency 
 to tuberculosis. Jean died, and his wife became 
 phthisical. She was remarried to Louis, who had 
 likewise no phthisical taint; Louis and Antoinette 
 both died of phthisis. The niece of the latter, equally 
 without phthisical taint, contracted the disease in 
 nursing her aunt, then married, and her husband was 
 10 
 
226 MICROBES. FERMENTS, AND MOULDS. 
 
 in his turn attacked by phthisis. All these people 
 resided in a place in which it was easy to verify the 
 absence of hereditary taint." 
 
 Here are other observations of the same nature : 
 
 " A young woman without hereditary taint nursed 
 a phthisical patient and contracted phthisis. She 
 returned home, and communicated the disease to the 
 six sisters with whom she lived. One sister survived, 
 but she was not living with her family. 
 
 " A soldier became phthisical while with his regi- 
 ment, and was therefore discharged, and returned to 
 his family. His father, mother, two brothers, and a 
 neighbour who nursed them, became phthisical. Yet 
 none of them were predisposed by hereditary taint. 
 
 " A girl returned from school in consumption ; on 
 her death her room and clothes passed to her sister, 
 who died of the same disease. A third sister died 
 under like conditions. As their parents still survive, 
 it is clear that the disease was not due to heredity." 
 
 This does not imply that heredity plays no part 
 in the transmission of the disease, for the contrary is 
 proved ; yet such transmission often occurs after the 
 child is born, and sometimes the nurse by whom it 
 is suckled may be the source of contagion. 
 
 In the case of children brought up by hand, the 
 infection may come from cow's milk which has not 
 been boiled. Cows are often attacked by tuberculosis, 
 and numerous bacilli have been found in the teats and 
 milk of these animals. This indicates the necessity 
 
THE MICROBES OF HUMAN DISEASES. 227 
 
 of boiling the milk used for food, especially in the 
 case of children, at any rate when the source is un- 
 known.* 
 
 Phthisis is, as we know, a slow disease, probably 
 because the microbe is anaerobic, and lives within the 
 cellular tissue, not in the blood, which it merely tra- 
 verses. The slow progress of the disease explains the 
 cases of spontaneous cure effected by the expulsion of 
 the microbe in the sputum, or by the tubercles passing 
 into a cretaceous condition, which causes the destruc- 
 tion of the bacteria encysted in them. Hence also 
 the fact that all the causes which weaken the consti- 
 tution, bad food, overwork, inflammatory diseases, 
 pregnancy, etc., hasten the end of consumptive per- 
 sons. Those who are attacked by the disease may, 
 if rich enough to live in the South, and to follow 
 with care the hygienic prescriptions of the physician, 
 often attain an advanced age, in spite of the lesions 
 which remain latent in the organism, provided also 
 they commit no imprudence in the matter of diet. 
 
 It is therefore important to maintain the strength 
 of consumptive patients by tonics, by a nourishing diet, 
 and by an hygiene as strictly protective as possible. 
 The good effects of creosote, of sulphur waters, etc., 
 are due, as in diphtheria, to the attenuation of the 
 
 * This precaution is equally efficacious to ward off typhoid fever. 
 In several epidemics of this disease, and especially in England, inquiry 
 has shown that milk was the vehicle of contagion, either from the 
 water with which it was adulterated, or from that which was used 
 to wash the vessels in which it was pluc.d. 
 
228 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 virulent properties of the microbe. Hansen considers 
 that alkalis, not acids, are the best antiseptics in this 
 disease. 
 
 Tubercular leprosy, termed elephantiasis by the 
 ancients, is caused by tubercles seated in the skin, 
 and containing a bacillus greatly resembling that of 
 phthisis, but larger (Fig. 92). This microbe is anae- 
 
 Fig. 92. Bacilli of leprosy, encysted in the sxibcxitaneous connective tissue of the skin 
 (much enlarged). 
 
 robic, and can only live in the dermic cells, in which 
 it is encvsted. Hence the treatment which experi- 
 ence, preceding the theory, showed to be the most 
 efficacious : instead of keeping the ulcers covered, they 
 should be exposed to the air and sun, often washed, 
 and kept as clean as possible. This disease, which is 
 essentially contagious, is very rare in Europe, but 
 common in Egypt and throughout Asia. 
 
THE MICROBES OF HUMAN DISEASES. 229 
 
 XII. THE MICROBE OF PNEUMONIA. 
 
 One of the most important micrographic dis- 
 coveries of late years is that a microbe is always 
 present in inflammation of the lungs, or pneumonia. 
 This disease was long considered, and is still con- 
 sidered by the majority of doctors, to be altogether 
 independent of any parasitic infection. It is such 
 a matter of tradition, both among patients and their 
 doctors, to ascribe this disease to accidental causes, 
 and especially to a sudden chill, that the parasitic 
 doctrine of pneumonia at once encountered a lively 
 
 Fig. 93. Micrococci in eputum of pneumonia : b, d, free, or encysted iu the lymphatic 
 cells a, c ; n, nuclei of cells (much enlarged). 
 
 opposition. It is, however, now impossible to deny 
 the important part taken by microbes in the trans- 
 mission of this disease. 
 
 The microbe of pneumonia was discovered by 
 Friedlander and Talamon in 1882. It consists of 
 micrococci, often associated in an 8 or in short chains 
 (Fig. 93), and found in the sputum and lungs of 
 pneumonic patients, either detached or encysted in the 
 lymphatic cells. 
 
230 MICROBES, FERMENTS, AND MOULDS. 
 
 Under a strong magnifying power, this micrococcns 
 is seen to be shaped like a lance-head, and short rods, 
 terminating in a cone, are found with it. It is probable 
 that the micrococcus is the early form of the microbe, 
 which becomes a bacillus in the adult form (Cornil). 
 
 The presence of a microbe in pneumonia explains 
 many facts which had remained obscure in this 
 disease, especially the epidemics in a room or house, 
 when several persons living together are successively 
 attacked by pneumonia. It likewise explains the 
 resemblance, which has long been indicated by their 
 common name, between the pneumonia of man and 
 the contagious pneumonia of cattle, which is well 
 known to be essentially epidemic, transmissible by 
 contact and inoculation. 
 
 A culture of the microbe of pneumonia can be 
 made, and when it is inoculated into the tissue of the 
 lung, it produces in animals a true pneumonia. 
 
 XIII. SOME OTHER DISEASES CAUSED BY MICROBES. 
 
 We shall only say a few words about several other 
 diseases, admitted to be contagious, and in which the 
 presence of a special microbe has been ascertained. 
 
 In the pus-corpuscles of gonorrhoea, very minute 
 and mobile micrococci may be observed, often associated 
 in pairs, in fours, or in a small mass, but rarely in 
 chaplets (Fig. 94). 
 
THE MICROBES OF HUMAN DISEASES. 231 
 
 The same micrococcus, or, at any rate, a microbe 
 wliich cannot be distinguished from it, is often found 
 in the purulent ophthalmia of new-born infants. It 
 is difficult to admit, even when we make allowance 
 for the great susceptibility of an infant's eyes at the 
 moment of birth, that such ophthalmia is always of 
 gonorrhceal origin. However this may be, the 
 micrococci of purulent ophthalmia resemble those of 
 gonorrhoea, and the same treatment is applicable. 
 The solution of nitrate of silver in a diluted form, 
 generally employed in maternity hospitals, as a pre- 
 
 Fig 94. Cells of gonor hceal pus 2i hours after its discharge. Within may be seen 
 several form> ol fission of their nuclei, and microcoici moving in the protoplasm 
 (x GOJ diam.) 
 
 ventive treatment of infant ophthalmia, has con- 
 siderably reduced the intensity of this disease. 
 
 The red, malodorous sweat of the armpits is due 
 to the presence of a microbe, which is found free in 
 the sweat, or massed in the form of a zoogloea, and 
 adherent to the hair of the skin. The red colour is 
 not due to iron, for no trace of this metal is revealed 
 by analysis ; it approximates in its nature to that of 
 Micrococcus prodigiosus. It may be cultivated in 
 
232 MICROBES, FERMENTS, AND MOULDS. 
 
 white of egg at a temperature of 87, in which it 
 retains its characteristic colour. 
 
 In a sweating foot, of which the smell is so 
 offensive, Rosenbach found a short, thick rod, which 
 is at once aerobic and anaerobic, is rapidly developed, 
 and retains its offensive smell when cultivated (Fig. 95). 
 
 In the gangrene of long bones, the same observer 
 
 * 
 
 Fig. 95. Bacillus of Fig. 96. Saprogenic bacillus 
 
 feet-sweat. of osseous gangrene. 
 
 has found a similar bacillus, which, like the foregoing 
 one, produces by inoculation a local affection, more or 
 less strongly marked (Fig. 96). 
 
 Warts. We know that a wart is self-sown, and 
 appears to contain a contagious principle. This is 
 Tomasi Crudeli's Bacterium porri, and is minute and 
 in the form of an 8. 
 
 Among the diseases due to microbes we must 
 include mumps, epidemic goitre, epithelial xerosis of 
 the eye, polypus of the nasal canal, of which the 
 concretions are formed of Streptothrix Fovsteri, etc. 
 
 XIV. THE MICROBE OF ERYSIPELAS. 
 
 Erysipelas belongs both to internal and external 
 pathology. It is sometimes manifested as a special 
 
THE MICROBES OF HUMAN DISEASES. 233 
 
 primary disease, characterized by the inflammation of 
 the skin, and sometimes as a secondary complication 
 of wounds, sores, and surgical operations. In any case, 
 the course taken by the disease and its contagious 
 nature enables us to assume the presence of a microbe. 
 Martin, Yolkmann, and Hiiter found bacteria in the 
 patches of skin ; and Hayem found them in the pus of 
 meningitis, which followed erysipelas of the face. 
 Lukomski was able to inoculate rabbits with the 
 disease, which may also be communicated by vaccine 
 lymph, taken from a child suffering from erysipelas. 
 Fehleisen has cultivated the microbe in a pure state, 
 
 Fig. 97. Section of the skin in erysipelas : the interfascicular space (e) is full of 
 microbes (m) in s's or chains; t, connective tissue (x 600 d.aui.). 
 
 and has inoculated man with it, always reproducing 
 erysipelas with its characteristics and typical course. 
 Antiseptics, such as carbolic acid and analogous sub- 
 stances, employed either as outward applications or as 
 subcutaneous injections, have been successful in many 
 instances in arresting the development of the disease. 
 
 Erysipelas serves as the transition to those diseases 
 within the domain of surgery, and which are generally 
 due to sores, wounds, arid operations. 
 
234: 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 XV. MICROBES OF Pus; PY^MIA AND SEPTICAEMIA. 
 
 Sores and surgical operations are often followed 
 by a general poisoning of the blood and of the whole 
 system a severe affection which is rapidly fatal, and 
 characterized by the presence of pus-corpuscles in con- 
 siderable numbers in the blood and in the principal 
 organs. Together with these pus-corpuscles there is 
 always a special microbe, termed Micrococcus septicus, 
 which, like that of diphtheria, may either appear free 
 or in the form of chaplets (vibrio), or in the interior 
 of the colourless corpuscles of pus, or embryonic cells, 
 of which it effects the rupture in the form of zoogloea. 
 
 This microbe, or others of 
 allied species, are the im- 
 mediate cause of that poison- 
 ing of the blood which is 
 termed pyaemia, septicaemia, 
 traumatic fever, puerperal 
 fever, post-mortem wounds, 
 etc. The germs of Micro- 
 coccus septicus are intro- 
 duced into the blood, and 
 multiply there, through the exposed surface of a wound, 
 or sometimes by means of the instrument which caused 
 it (Fig. 98). 
 
 When the instrument causing the wound is charged 
 with microbes, it is not necessary that the wound 
 
 Fig. 98. Pus-corpuscles of puerperal 
 peritonitis, lull of microccci in 
 chains ( x SOU diam.). 
 
THE MICROBES OF HUMAN DISEASES. 235 
 
 should be gaping: there is in this case a true inocula- 
 tion. Such is the case in a post-mortem wound. The 
 experiments of Tedenat, of Lyons, show that when 
 decomposition has not begun in the corpses of healthy 
 persons, who have died by violence, the autopsy pre- 
 sents no danger; but this is not the case when death 
 is due to an infectious disease, pyaemia, erysipelas, etc. 
 On the other hand, the puncture will have no evil 
 results if the bleeding is profuse, or if the microbes 
 and their germs have been removed by immediate 
 suction. Some hours after death, all corpses contain 
 microbes, which have penetrated into the blood owing 
 to the softening of the tissues, and which either come 
 from the external air or from the digestive canal. 
 
 The enormous number of pus-corpuscles which 
 appear in a very short time in the blood was for a 
 long while a problem for physicians. It is now known 
 that these corpuscles have their source not only in the 
 wound, but also in all parts of the vascular system. 
 and especially in the capillaries, according to Schiff s 
 theory. The microbian theory may easily be made 
 to agree with the latter, and Sternberg was the first 
 to suggest that it appears to be the function of the 
 colourless corpuscles to take possession of the bacteria 
 introduced into the blood, and to destroy them. We 
 know, in fact, that the colourless corpuscles do take 
 possession of all foreign particles, such as micrococci and 
 bacteria, introduced into the blood, and in some sense 
 encyst them in their protoplasm. When these bacteria 
 
236 MICROBES, FERMENTS, AND MOULDS. 
 
 multiply in the blood, they must necessarily have an 
 irritating effect on the walls of the blood -capillaries 
 and this appears in the swelling of the cells and their 
 return to the spherical form ; in a word, they are 
 transformed into embryonic or migratory cells (accord- 
 ing to Cohnheim's theory). These do not differ, or 
 only differ slightly, from the colourless corpuscles of 
 the blood, and are pus-corpuscles. This new theoiy 
 is in accordance with the facts daily presented to us 
 in the treatment of surgical diseases. 
 
 XVI. MICROBES OF SOME OTHER DISEASES, RESULTING 
 FROM WOUNDS. 
 
 Whitlow and Agnail. These two complaints are 
 produced by pricking the finger with some instru- 
 ment charged with microbes. Chains of bacteria or 
 micrococci are always found in the collection of pus 
 or serous discharge. 
 
 Boil and Carbuncle. The pus from a boil contains 
 micrococci, which Pasteur first observed, and which he 
 has cultivated in an infusion of yeast and in chicken- 
 broth. 
 
 It was found by Rosenbach in osteomyelitis, and 
 was termed by him Staphylococcus pyogenus aureus 
 (Fig. 99). 
 
 Carbuncle only differs from a boil in its larger 
 size, and contains the same microbe. It is well known 
 
THE MICROBES OF HUMAN DISEASES. 
 
 237 
 
 Fig. 99. Roil microbe 
 (xtaphylococcus pyo- 
 yenusaunus: Rosen- 
 bach). 
 
 that it is readily and spontaneously self-inoculated, 
 and that boils and carbuncles rarely occur singly 
 in the same individual. Diabetic 
 patients are very subject to this 
 affection, yet the microbe does not 
 admit of culture in sugared water. 
 
 Phlegmon. This is the name given 
 to the suppuration of the subcutaneous cellular tissue, 
 caused by contusions, wounds, and medical injections 
 of morphia or any other sub- 
 stance. Microbes are always 
 found associated in 8's or in 
 long sinuous chains (Fig. 
 100). In all these cases there 
 has been some communica- 
 tion with the outer air, for 
 wounds which are really sub- 
 cutaneous fractures, for ex- 
 ample even when accom- 
 panied by abundant haemorr- 
 hage, heal without suppuration, and microbes are not 
 present. 
 
 ,'. 100. Pus of phlegmon, contain- 
 ing chains of iiiicrococci (x looo 
 diam.). 
 
 XVII. MODE OF ACTION OF MICROBES IN DISEASE. 
 PTOMAINES. 
 
 The question how microbes act in disease has long 
 been doubtful, but the progress of science tends to 
 clear away obscurity. 
 
238 MICROBES, FERMENTS, AND MOULDS. 
 
 The first idea was that microbes introduced into the 
 blood or tissue of an animal acted like parasites of 
 a higher organism intestinal worms, for instance by 
 deriving their nourishment from their medium, and 
 developing at its expense. It is evident that this 
 must be the case, and that in anthrax, or splenic fever, 
 for example, the bacilli which swarm in the blood 
 abstract from the red corpuscles the oxygen they 
 require, and thus produce asphyxia and the death of 
 the animal. 
 
 Yet it often happens, even in anthrax, that death 
 is so rapid, that the bacilli have not yet had time to 
 develop in the blood in numbers sufficient to produce 
 such fatal effects. So, again, in cholera, the comma 
 bacillus has not yet been found in the blood, and yet 
 cases of sudden death are not uncommon in this 
 disease. Some other explanation is therefore required. 
 
 Panum first showed, from the study of the pro- 
 ducts of putrefaction, that a poisonous substance, 
 resembling snake-venom and vegetable alkaloids, is 
 developed as the ultimate product of the putrid fer- 
 mentation of organic matter. Twelve milligrammes of 
 this substance kill a dog, while neither ammonia nor 
 the acids which are first formed in this fermentation can 
 produce septicaemia. Bergemann and Schmiedeberg 
 have termed this poisonous substance septine. 
 
 Panum's researches have been recently resumed by 
 Selmi and Gautier, who have extracted from corpses 
 and putrefying organic matter a certain number of 
 
THE MICROBES OF HUMAN DISEASES. 239 
 
 poisonous substances greatly resembling vegetable 
 alkaloids, and termed by them ptomaines. 
 
 The action of ptomaines may be compared to that 
 of strychnine. Injected into the blood, even after 
 the removal of every living microbe, the ptomaines 
 produce fever, rigors, vomiting, diarrhoea, spasms, 
 torpor, collapse, and finally death. It is probable that 
 in some cases of poisoning by tainted meat or fish 
 their poisonous properties are due to the presence of 
 ptomaines. 
 
 But in all cases these ptomaines are shown to be 
 the product of putrid fermentation, which is always 
 effected in dead bodies by special microbes. Here the 
 ptomaines are due to the work of the microbes of 
 putrefaction, and are made by them, just as alcohol 
 and the carbonic acid of alcoholic fermentation arc 
 made by yeast, at the expense of the sugared liquid 
 in which they live and multiply. 
 
 Direct experiments show that when septine, from 
 which every microbe has been removed, is injected 
 into the human subject, it produces feverish disturb- 
 ance, but only causes death when introduced in con- 
 siderable quantities. If, on the other hand, there is 
 in the same individual a large suppurating wound, 
 exposed to the air instead of being covered by an air- 
 tight dressing, a purulent infection (septicaemia) will 
 almost certainly ensue, since the microbes introduced 
 by means of this wound will find in it a favourable 
 soil (pus and putrefying organic matter); they wiJl 
 
240 MICROBES, FERMENTS, AND MOULDS. 
 
 multiply in immense numbers, and manufacture of 
 these materials a great quantity of septic poison, at the 
 expense of the organism in which they are developed. 
 
 It is now admitted that the chief action of patho- 
 genic microbes, or, at any rate, of the most dangerous 
 among them, consists in the ptomaines which they 
 secrete within the body. This explains why death by 
 cholera is so rapid and even sudden, when the comma 
 bacillus is still only found in the intestines. Although 
 this micro-organism has not been absorbed by the 
 intestinal mucous membrane and carried into the 
 blood, the poisonous alkaloid, or ptomaine, which it 
 secretes is certainly present, and to this the nervous 
 symptoms, such as cramp, etc., which characterize this 
 disease, may probably be ascribed. 
 
 Pouchet has extracted from the fseces of choleraic 
 patients, a special alkaloid of the nature of ptomaine ; 
 and quite recently, in August, 1885, he has found traces 
 of the same alkaloid in infusions of pure culture of 
 Koch's comma bacillus.* 
 
 In conclusion, at the present stage of our know- 
 ledge, it may be admitted that the action of patho- 
 genic microbes on the system is complex, and may 
 be analyzed as follows : (1) The action of a living 
 
 * This affords the germ of the idea of a new process for preparing 
 lymph, which has perhaps already been put in practice. A Spanish 
 physician states that the secret process employed by Ferran simply 
 consists in filtering his culture infusion by means of the Chamberlaud 
 filter, and using this liquid for inoculation, since it contains the 
 ptomaine of cholera without its bacillus (?). 
 
TIIK MICROBES OF HUMAN DISEASES. 241 
 
 parasite, which is nourished and multiplies at the 
 expense of the fluids and gases of the system ; (2) the 
 formation by this parasite of a poisonous substance 
 (ptomaine), of which the elements are derived from the 
 organism, and it acts as a poison on this organism. 
 
242 MiCKOliES, FERMENTS, AXD MOULDa 
 
 CHAPTER VI. 
 
 MEANS OF DEFENCE AGAINST MICROBES. 
 
 I. ANTISEPTIC TREATMENT OF WOUNDS: GU^RIN'S 
 PROTECTIVE DRESSING; LISTER'S DRESSING. 
 
 THE first and most brilliant application of the theory 
 of microbes to human therapeutics has been made in 
 the treatment of wounds. 
 
 Since it is admitted that the danger of a wound 
 or of a surgical operation is chiefly due to the contact 
 of the wound with the external air, which is laden 
 with germs, or with the dressing which may contain 
 microbes, all the surgeon's efforts should be directed 
 to preventing such contact. This may be accom- 
 plished by several processes, now generally employed 
 by surgeons, and these may be regarded as the noblest 
 achievement of modern surgery. 
 
 In Guerin's protective dressing, this skilful surgeon 
 has made a practical use of Tyndal's and Pasteur's 
 researches into the nature of air-germs. We have 
 
MEANS OF DEFENCE AGAINST MICKOBES. 243 
 
 already said that air filtered through a sufficiently thick 
 layer of cotton wool becomes free from germs. Guerin 
 covers that part of the bod} T in which the wound is 
 situated with several layers of cotton wool, carefully 
 applied and confined by a cotton bandage. This 
 dressing permits the access of air to a certain extent, 
 but the air is filtered through the cotton wool, which 
 arrests all microbes ; and this is proved by removing 
 the dressing after the lapse of several days, when the 
 wound will be found to be in a satisfactory state, and 
 in process of healing. A certain amount of pus is 
 produced, but much less than in the old-fashioned 
 lint dressing, and this pus is not putrefied, since the 
 germs which are the agents of putrefaction have 
 been excluded. 
 
 The English surgeon, Lister, has arrived at the 
 same result by a more complicated process, which 
 has, however, been generally adopted in France. His 
 process is based on the use of carbolic acid as an 
 antiseptic or destructive agent of microbes and germs. 
 Whenever an operation is to be performed, the instru- 
 ments, the surgeon's hands, those of his assistants, 
 and all the materials used for dressing, must be 
 steeped in a sufficiently dilute solution of carbolic 
 acid ; throughout the operation the wound must be 
 surrounded with a spray of the same solution, playing 
 over the hands of the surgeon and over all he touches. 
 The same solution and the same precautions are 
 applicable to the treatment of all wounds, whatever 
 
244 MICROBES, FERMENTS, AND MOULDS. 
 
 be their origin, and should be renewed whenever the 
 wound is dressed. 
 
 We cannot describe Lister's dressing in detail, but 
 will only mention (1) that the skin surrounding the 
 region of the operation, the surgeon's hands, and the 
 instruments are washed with a carbolic solution of two 
 to three per cent. ; (2) the spray contains one per cent, 
 of carbolic acid ; (3) the ligature of the arteries is done 
 with carbolized catgut, which is eventually dissolved 
 in the wound; (4) the drainage-tube usually arranged 
 for the outflow of the discharge is likewise carbolized ; 
 (5) so also are the eight folds of gauze, which is 
 used instead of linen dressings ; (6) a protective, con- 
 sisting of green oiled silk, steeped in carbolic acid 
 and varnished like eourt-plaister, is interposed to 
 prevent the irritating effect of the gauze on the 
 wound; (7) an impermeable mackintosh, laid between 
 the seventh and eighth folds of gauze, prevents the 
 penetration of fluids. 
 
 The admirable results obtained by Lister's method 
 are the strongest confirmation of the truth of the 
 theory of microbes. Since its introduction into 
 medical practice, mortality among the wounded and 
 among thesurgical patients has considerably diminished, 
 and operations formerly considered impracticable have 
 been undertaken and successfully carried out. 
 
 Carbolic acid is not the only antiseptic which 
 affords excellent results by destroying, or at all events 
 by attenuating, the virulence of microbes and their 
 
MEANS OF DEFENCE AGAINST MICROBES. 245 
 
 germs. Alcohol, which has been long in use, boracic 
 acid, salicylic acid, thymol (essence of thyme), and 
 eucalyptol (the essence extracted from Eucalyptus 
 globulus), and many other substances, have been 
 employed both internally and externally with this 
 object, and most of them take a more or less impor- 
 tant place in the therapeutics of those diseases caused 
 by microbes. 
 
 II. HYGIENE OF DRINKING-WATER: WATER FREE 
 FROM MICROBES ; CHAMBERLAND FILTER. 
 
 The researches carried on by Miquel for some years 
 at the Observatory of Montsouris, at the Pantheon, 
 and in other parts of Paris, teach us that living 
 bacteria are more rare in the atmosphere than had 
 been generally supposed. We have already said that 
 air is the great purifier of microbes, which it destroys 
 by desiccation. Even in the infection of wounds, it 
 is probable that the liquids and linen formerly 
 employed for dressings transported the microbes in 
 greater number than the air, however charged it 
 might be with these organisms in the neighbourhood 
 of a hospital. 
 
 In the water which supplies large towns, whether 
 furnished from wells or streams, a large number of 
 microbes are, however, found in a state of perfect vitality. 
 This is quite natural, since we know that these plants 
 
246 MICROBES, FERMENTS, AND MOULDS. 
 
 cannot exist without moisture, and they find in such 
 water the organic matter which nourishes them. The 
 rivers receive them by the sewers which discharge into 
 them, the wells by infiltration of the soil, and thus 
 ill times of epidemic, the microbes of typhoid fever 
 and of cholera are always to be found in running or 
 stagnant waters, which therefore become the vehicle 
 of infectious diseases. 
 
 Well-water, owing to its stagnant nature, and to 
 the infiltration to which it is liable from cesspools 
 which are often leaky, is more dangerous than 
 running water. About two years ago, an epidemic 
 of typhoid fever, which occurred in one quarter of 
 Angers, was stopped by introducing a supply of water 
 from the Loire ; up to that time well-water had been 
 exclusively in use. 
 
 Well-water in Bread-making. In many places 
 well-water is still too often used for making bread 
 instead of running water. There are probably many 
 reasons for this preference. Bakers, without assigning 
 any reason for the fact, assert that well-water causes 
 the bread to rise better ; and moreover, in towns, sucli 
 as Angers, where there is a water company, river- 
 water costs money, while well-water may be had for 
 nothing. About 50 per cent, of water is used in 
 making bread, which explains the preference shown 
 by bakers for well-water, and also the importance 
 ascribed by hygienists to the purity of the water 
 used in bread-making. 
 
MEANS OF DEFENCE AGAINST MICROBES. 247 
 
 In fact, direct experiments, made with a maximum 
 registering thermometer enclosed in the dough, shows 
 that the internal temperature of the loaf, that of the 
 crumb, rarely rises to 100. We know that this tem- 
 perature does not suffice to destroy most microbes, 
 still less their germs, for which a temperature of from 
 115 to 160 is necessary. 
 
 In 1884, Bouvet, a chemist, and Preaubert, a pro- 
 fessor at the Lycee, were commissioned by the munici- 
 pality of Angers to make a microscopic examination of 
 numerous specimens of well-water used by bakers in 
 their trade in different parts of the town. The exami- 
 nation of deposits, either obtained spontaneously by 
 allowing the water to stand for twenty-four hours, or 
 by testing the water with osmic acid, in accordance 
 with Certes's process, almost invariably revealed the 
 presence not only of the ova of ascarides, but of 
 numerous microbes some of them harmless, like 
 Bacterium termo ; others doubtful, on account of their 
 forming chains like the micrococcus (two species of 
 different form), and resembling Micrococcus dipTithe- 
 ricus. Now, croup may be regarded as endemic at 
 Angers. In four wells out of the twenty-five ex- 
 amined these microbes were found in great numbers. 
 It must be noted that micrococci are not found in 
 strongly aerated water, but only in that of which 
 the organic deposit is abundant. 
 
 Well-water must, therefore, be generally condemned, 
 both for drinking purposes and for the making of 
 
248 MICROBES. FERMENTS, AND MOULDS. 
 
 bread. Spring- water, and still more river-water, as 
 it is now supplied in towns by a system of pipes, 
 is not free from organic matter, nor from microbes, 
 although they are less abundant than in well-water. 
 Purification is therefore necessary. 
 
 With this object, it is recommended, especially in 
 times of epidemic, to boil the water, so as to destroy 
 the microbes contained in it. But this process expels 
 the gases, and reduces the proportion of salts in solu- 
 tion, thus rendering the water heavy and indigestible. 
 It has, therefore, been suggested that only weak 
 mineral waters should be drunk, such as that of 
 Saint Galmier, which, if taken at the source and 
 immediately placed in hermetically sealed bottles, 
 contains very few microbes. But this process is 
 costly, so that only rich people can avail themselves 
 of it. The most practicable mode of purifying table- 
 water and rendering it wholesome is by the use of 
 filters. 
 
 Ordinary Filters. Chamberland's Microbe Filter. 
 Every one is acquainted with the common filter, 
 made with crushed sandstone, charcoal, etc., which 
 should be found in all households and kitchens. This 
 generally suffices to free water from organic matter, 
 and especially from the ova of ascarides (intestinal 
 worms), which, when introduced into the system, 
 develop and cause inconvenience to so many children, 
 and even to grown persons. It is impossible to insist 
 too strongly on the fact that the presence of ascarides 
 
MEANS OF DEFENCE AGAINST MICROBES. 
 
 in the intestines is always due to the use of unflltered 
 water, and this should enforce the general use of 
 filters, which is often neglected even by those who 
 cannot be deterred by the relatively moderate cost 
 of an instrument which it is almost impossible to 
 wear out. An ordinary filter, however, can arrest a 
 very small proportion of microbes, which are much 
 more minute than the ova of ascarides. 
 
 A filter has, therefore, been devised, so perfect as 
 to allow the passage of no solid matter in suspension, 
 not even the most minute organisms contained in 
 drinking-water. This result is effected by the filter 
 invented by Chamberland in Pasteur's laboratory. 
 The filter is formed (Fig. 101) of a vessel of biscuit- 
 ware, A, shaped like a candle (whence its name of 
 bougie Chamberland) ; this is fastened to the lower 
 part of the metallic receiver D, which receives under 
 pressure the water coming from the cock E. This 
 vessel consequently filters the water from without to 
 within, and it flows through the orifice B, perfectly 
 free from solid particles, as it appears from a micro- 
 graphic examination. 
 
 Fitted to the distributing water-taps of many 
 houses in Paris, and especially in lycees, the Cham- 
 berland filter acts under the normal pressure of the 
 water-conduit, and, by a new modification of the 
 inventor, can even act without such pressure. For 
 this purpose he arranges his filters in a battery, from 
 eight to ten or more, in a cylindrical receiver, closed 
 
250 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 in its upper part. This receiver is connected by a 
 caoutchouc tube with the vessel which contains water 
 
 Fig. 101. Section and elevation of Chamber-land's filter. 
 
 for filtering. When the vessel is placed two or three 
 metres above the filter, from fifteen to twenty litres 
 
MEANS OF DEFENCE AGAINST MICROBES. 251 
 
 of perfectly pure water may be obtained in the course 
 of an hour. Under the pressure of the taps of the 
 Paris water-supply, the jet of the filtered water is 
 as strong as that of the pipes used for watering our 
 gardens; in fact, it gives out four or five litres a 
 minute under the pressure of two or three atmospheres. 
 
 Preservation of Alimentary Substances. Appert's 
 Protective Process, etc. We have already said that 
 organic substances may be preserved unchanged for 
 an indefinite time, as long as they are protected from 
 the microbes and germs in the air. This was shown 
 by Pasteur's exhaustive experiments. He took urine 
 and blood, and transferred them directly from the 
 animal organs into glass flasks which had been pre- 
 viously sterilized or deprived of all germs. These 
 flasks were hermetically closed and kept for forty-five 
 days. When opened at the end of that time, it was 
 ascertained that the smell and appearance of the 
 liquids were unchanged, that no putrid gas had been 
 developed, and even that some of the oxygen in the 
 flasks had not been absorbed. 
 
 Most of the processes in use, even before this 
 experiment, for the preservation of food substances, 
 are only the practical application of this principle : 
 the exclusion of microbes and germs. 
 
 Appert's process, now so generally used to preserve 
 meat and vegetables, consists in enclosing the sub- 
 stances to be preserved in tins, which are hermetically 
 closed, and heated to a temperature of 110, so as 
 
252 M1CKOBES, FERMENTS, AND MOULDS. 
 
 to ensure the destruction of all germs. A very small 
 aperture is left at the top of the case for the escape 
 of steam and air, which is closed with a drop of solder 
 before the ebullition of the liquid within is completely 
 over. 
 
 The envelopment of meat in its own fat, its pre- 
 servation in sugar, wax, etc., are analogous protective 
 processes, always employed at a high temperature. 
 
 When meat is smoked, the aromatic principles of 
 carbolic acid, creosote, etc., contained in the smoke, 
 destroy the ferments and prevent the subsequent 
 development of air-germs. It is, therefore, a true anti- 
 septic, analogous to the salts used to preserve meat 
 or fish by pickling. Meat may also be preserved by 
 desiccation, when it is cut in thin strips and exposed 
 to the sun and air. This constitutes the jerked beef 
 of South America. 
 
 Excellent results are now obtained by drying meat 
 at from 35 to 55 in a stove through which a current 
 of dry air is passed. The powdered meats to be ob- 
 tained from chemists, which are of great use in nourish- 
 ing the sick and convalescent, are prepared by an 
 improvement on this process. They are absolutely 
 free from smell, and will keep as long as they are 
 protected from damp. Vegetables cooked by steam, 
 and then compressed and dried, may be kept for 
 several years. 
 
 Refrigeration by ice has been used to preserve 
 meat. But when congelation has occurred in the 
 
MEANS OF DEFENCE AGAINST MICROBES. 253 
 
 fluids contained in the muscular tissue, putrefaction 
 sets in, and rapidly increases, as soon as the tempera- 
 ture rises a few degrees above freezing-point. The 
 meat also acquires an unpleasantly sweet taste. It 
 will be remembered that the first cargo of frozen 
 American meat which was brought to Paris had con- 
 tracted an unpleasant taste and was very soon 
 tainted. When meat, game, or fish is kept in ice, the 
 congelation of the fluids contained in their tissues 
 must therefore be avoided. 
 
 Many antiseptics, vinegar, alcohol, glycerine, etc., 
 may likewise be used to preserve meat and other 
 alimentary substances. 
 
 Antiseptics and Disinfectants. We will discuss 
 the substances which are thus designated, especially 
 from the hygienic point of view, and as a preventive 
 treatment of contagious diseases, indicating the action 
 of these substances on microbes. 
 
 Antiseptics have been studied by Jalan de La Croix 
 with reference to their action on microbes in general. 
 His experiments were performed on culture liquids 
 made of the juice of cooked meat, into which he 
 introduced an equal number of drops of the same 
 broth, which contained fully developed bacteria. He 
 next ascertained the dose, in milligrammes, of ari 
 antiseptic substance which would suffice either to 
 arrest their multiplication or to destroy the microbes, 
 and consequently to sterilize the liquid. 
 
2")4 MICROBES, FERMENTS, AND MOULDS. 
 
 He analysed in this way twenty substances con- 
 sidered to be antiseptic, or commonly used as such. 
 He has published a table in which these substances 
 are classified in their order of activity, and it includes 
 among others the following antiseptics, which we cite 
 in the order assigned to them : 
 
 Corrosive sublimate (mercuric chloride) No. 1 
 
 Chloride of lime at 98 No 3 
 
 Sulphurous acid No. 4 
 
 Essence of mustard No. 9 
 
 Thymol No. 13 
 
 Salicylic acid No. 14 
 
 Carbolic acid No. 10 
 
 Boracic acid No. 18 
 
 Alcohol No. 19 
 
 Essence of eucalyptus No. 20 
 
 The three last substances are incapable of steri- 
 lizing culture broths. 
 
 This table shows that carbolic acid, which is now 
 so much in use, does not destroy microbes so efficiently 
 as salicylic acid, permanganate of potassium, thymol, 
 benzoic acid, bromides, and iodine. In this estimate, 
 however, we must take into account how far the use 
 of each antiseptic is practicable. 
 
 Thus, corrosive sublimate, which these experiments 
 show to be the best antiseptic, can be used as an 
 external lotion, but it cannot be given internally in 
 doses sufficient to produce the desired effect. Eighty 
 milligrammes are required to sterilize a litre of broth, 
 and forty to arrest the development of bacteria. 
 Twenty milligrammes will not effect this result, and 
 
MEANS OF DEFENCE AGAINST MICROBES. 255 
 
 this latter dose is a maximum which it is almost 
 impossible to exceed in man in the course of twenty- 
 four hours without poisoning him. 
 
 Sulphurous acid is very effectual when employed 
 in fumigations, but it does not penetrate to the interior 
 of the tissues, and only acts on the microbes on their 
 surface. It does not destroy their spores. 
 
 Iodine has great effect in this respect. Davaine 
 has ascertained that seven milligrammes of iodine 
 suffice to destroy the bacteria of anthrax in a litre 
 of liquid. Instead of a hot iron, tincture of iodine 
 might, therefore, be used to cauterize the bites of 
 poisonous flies, carbuncles, and the pustule of anthrax. 
 
 Koch states that a solution of five per cent, of 
 carbolic acid is required to destroy the spores of 
 anthrax in twenty-four hours ; but the bacilli them- 
 selves are destroyed -by a solution of one per cent. 
 A solution of 002 per cent, iodine, or 007 per cent, 
 of bromine prevents the development of bacilli. 
 
 Chloride of zinc arid sulphate of iron, which have 
 been recommended as disinfectants, are very inferior 
 to chloride of lime, which takes the third place in the 
 list, the second being occupied by chlorine. 
 
 Alcohol arrests the development of bacteria and 
 their spores, but does not destroy the latter, even 
 at the end of a month, as it is stated by Claude 
 Barnard. 
 
 Babes regards essence of mustard as an excellent 
 preservative from cholera. If a drop of this essence 
 
256 MICROBES, FERMENTS, AND MOULDS. 
 
 is put at the bottom of a bell-glass which covers a 
 culture of comma bacilli, it arrests their development 
 and destroys them within forty-eight hours. 
 
 When cholera is epidemic, it has been suggested 
 that rum or cognac should be taken, to which salicylic 
 acid is added, in the proportion of 25 grammes to the 
 litre. A. petit verre, or three teaspoonsful, of this mixture 
 may be taken between meals in coffee, tea, or grog. 
 
 Redard has been recently occupied with the dis- 
 infection of the railway-waggons used for the trans- 
 port of cattle. He regards most of the substances 
 employed, including sulphurous acid, as insufficient. 
 The only effectual process is by steam, at a tempera- 
 ture of 110, which may be easily procured at the 
 railway stations. 
 
 As we have already said, the oxygen contained in 
 air is an excellent antiseptic, and the attempt has 
 been made to employ it ; but the experiments of Bert 
 and Regnard show that bacteria are only destroyed 
 by oxygen at a high pressure. As for oxygenated 
 water, it has not yet afforded the results which were 
 expected from it. 
 
 Finally, each species of microbe .appears to be 
 more or less sensitive to the action of different 
 therapeutic agents. Thus the effect of mercurial salts 
 on the microbe of syphilis was known before the 
 existence of the microbe itself was known ; that of 
 the salts of quinine and arsenic on the microbes of 
 intermittent fever, etc. 
 
MEANS OF DEFENCE AGAINST MICROBES. 257 
 
 We must, in conclusion, rely much more upon 
 measures of hygiene than on antiseptics to ward off 
 the attacks of the microbes which are factors of 
 disease. Even in Lister's dressing, it is probable 
 that the hermetic closing of the wound has, as it is 
 shown by Guerin's process, much more effect than 
 carbolic acid, which is shown by direct experiments 
 to be a feeble and generally an insufficient antiseptic. 
 
 We have still to speak of the preventive vaccina- 
 tions and inoculations on which medicine relies more 
 than on antiseptics; but this subject will be better 
 discussed in the following chapter, when we have 
 spoken of the processes of culture by which the 
 liquids destined for these inoculations are prepared. 
 
 18 
 
258 MICROBES, FERMENTS, AND MOULDS. 
 
 CHAPTER VIL 
 
 LABORATORY RESEARCH, AND CULTURE OP MICROBES. 
 
 THE processes employed in laboratories for the study 
 and culture of pathogenic microbes are now very 
 complicated, and they have attained a remarkable 
 degree of perfection. In such an elementary work as 
 this we can only give a general idea of these different 
 processes, and for details we must refer our readers to 
 the valuable work by Cornil and Babes, Les Bacteries, 
 in which the technique of laboratories devoted to the 
 histology of microbes is described with great accuracy 
 and clearness. 
 
 Microscopes. The best instruments for the research 
 and study of microbes are those of Zeiss, Jena, and 
 Verick, Paris. Immersion lenses, either for use in 
 water or in other homogeneous liquids, are indispen- 
 sable for the high magnifying power which is necessary 
 in order to see most bacteria distinctly. Condensers, 
 especially those of Abbe', made by Zeiss, are no less 
 useful in order to concentrate the luminous rays on 
 that point of the preparation which is to be specially 
 examined, and to place the bacteria in relief after 
 
LABORATORY RESEARCH, ETC. 259 
 
 they have been stained by the process we are about to 
 mention. 
 
 A preparation ought first to be examined under a 
 low magnifying power (from 50 to 100 diameters), so 
 as to study the topography of the object, and ascertain 
 the points at which the colonies of microbes may be 
 sought amid the tissues of a section, or of the matters 
 in suspension in the liquid. 
 
 We should then go on to a higher magnifying 
 power (for example, to from 500 to 700 diameters), 
 making use of the simple light of the mirror; and we 
 should ultimately come to the highest magnifying 
 powers (from 1000 to 1500 diameters), using immer- 
 sion-lenses and the condenser. 
 
 Instruments, Microtome. The instruments for fine 
 dissection are those commonly used in histology. In 
 addition, needles of glass and platinum are necessary, 
 and thin spatulas of nickel to convey the sections, etc. 
 
 The ordinary razor, which serves for hand sections, 
 will not do for the thin, wide sections necessary for 
 the discovery of bacteria. In this case a microtome 
 must be used, an instrument for making thin sections, 
 for which purpose those of Thoma or Verick are the 
 best. Sometimes the object to be examined is 
 hardened by freezing it with ether spray, since this 
 makes it possible to cut thin sections by hand. This 
 is Jung's process. 
 
 Non - staining Liquid Reagents. Acids, bases, 
 alcohol, oil of aniline, and other essences serve to 
 
260 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 dehydrate and partially decolourize preparations. 
 Canada balsam is used to mount them; and finally 
 distilled water, absolutely free from microbes, which 
 may be easily obtained by means of the Chamberland 
 filter already described, is used for washing instru- 
 ments, etc. 
 
 Mode of collecting the Liquids to be examined. In 
 order to collect the liquids to be obtained 
 in the wards of a hospital or elsewhere 
 (blood, urine, sputum, stagnant or sewer 
 water, etc.), pipettes, which may be either 
 straight or with twisted necks, are used, 
 ending in a capillary point closed by 
 heat, and in its upper part by a stopper 
 of fine, sterilized cotton wool. The 
 pipette is heated at a blowpipe flame, 
 in order to destroy the germs. When it 
 is to be used, the point is broken off, 
 and it is plunged into the liquid (dis- 
 charge from a freshly opened abscess, 
 blister of erysipelas, etc.), and an aspira- 
 tion is made through the other end. The 
 liquid is unable to rise above the level 
 of the twisted neck ; and this is important; 
 especially when the aspiration is made 
 by the mouth. The point is then resealed 
 at the lamp. The shape of these pipettes 
 may be varied according to the require- 
 ments, so long as the same precautions are always 
 taken to avoid mistakes. 
 
 1g. 102. Small 
 pipette with 
 twisted neck, 
 corked with cot- 
 ton wool and 
 sterilized. 
 
LABORATORY RESEARCH, ETC. 261 
 
 Preparations. Such precautions, and especially 
 the most scrupulous cleanliness, are necessary in 
 making preparations, since air, water, dust, the human 
 hand, and instruments may all introduce foreign 
 microbes. The instruments should be washed in abso- 
 lute alcohol, and it is still more effectual to heat them 
 to a temperature of from 150 to 200. 
 
 As to the liquids (pus, mucus, etc.), the upper sur- 
 face s,hould not be taken, but that which is nearest to 
 the tissues, and it should be spread on a thin slide 
 by a platinum wire, which has been heated red hot 
 and then allowed to cool. 
 
 When the tissues are to be examined, part of them 
 is detached by a knife which has been heated red hot. 
 It is placed in Jung's freezing microtome, in order to 
 cut sections, after it has been hardened in alcohol, to 
 which bichromate of potassium is sometimes added. 
 The sections are made as large as possible, and are 
 then instantly transferred to a capsule full of alcohol, 
 in which they spontaneously unfold. The glass or 
 platinum needle, and the nickel or platinum spatula, 
 serve to spread out and smooth these sections. 
 
 Staining Methods. Aniline dyes have the property 
 of giving a more vivid colour to the bacteria than to 
 the surrounding tissues, often even without destroying 
 them or altering their movements. This property has 
 been turned to account, and the staining of preparations 
 is now largely practised. 
 
 Methyl- violet, or fuchsin, in aqueous solution, serves 
 
262 MICEOBES, FERMENTS, AND MOULDS. 
 
 to stain the living bacteria in a drop of water, under 
 a cover-glass. A small drop of the staining liquid is 
 slowly diffused into the preparation, and gradually 
 tinges the bacteria without giving any sensible colour 
 to the liquid which contains them. When the comma 
 bacillus of cholera is thus treated, it is still capable of 
 motion after the lapse of twenty-four hours, and it will 
 continue to develop if the stage of the microscope is 
 heated to 25. 
 
 In sections which have been hardened or dried in 
 alcohol the bacteria have ceased to live, but they may 
 be stained with the following reagents Grenadier's 
 borassic carmine, hematoxylin, and tincture of iodine 
 may be respectively employed, according to the species 
 of microbe which is to be stained : Micrococcus, the 
 flagellum of bacteria, Bacillus amylobacter, moulds, 
 etc. 
 
 Aniline dyes, with an alkaline or acid basis, are 
 very numerous and varied ; methyl- violet and gentian 
 in oil of aniline, or in aqueous solution, rosine, saffronine, 
 Bismarck brown, purpurine, etc. 
 
 It is often desired to effect a double staining of the 
 section, the tissues, for example, being stained red, and 
 the bacteria violet, or conversely. Picrocarminate of 
 ammonium gives this effect by the following process : 
 After staining the preparation with methyl-violet, it 
 is dipped for a moment in the iodide solution, and 
 washed in water or weak alcohol ; it is then steeped 
 for some minutes in the picrocarminate, of which the 
 
LABORATORY RESEARCH, ETC. 263 
 
 colour is made lighter by washing with absolute 
 alcohol and oil of cloves, and the preparation is after- 
 wards mounted in balsam. The nuclei of the cells are 
 then of a carmine red, and the bacteria are violet; the 
 rest of the preparation is of a much paler colour. 
 
 Ehrlictis Method. We mentioned this method 
 when speaking of the bacillus of tuberculosis. It 
 consists in treating the sections or mounted prepara- 
 tion with a solution of methyl-violet in aniline oil, and 
 the colour is afterwards quickly discharged in nitric 
 acid ; the bacteria alone remain violet. Fuchsin, 
 methylene blue, coccinine, vesuvine, etc., are also em- 
 ployed in various processes for staining bacteria. 
 
 Measurement, Drawings, and Photographs. Bac- 
 teria are measured by comparing them with the 
 divisions of the micro-millimetre slide placed on the 
 stage of the microscope over the preparation. The 
 microbes may be drawn without much difficulty by 
 means of the camera lucida at least, after a little 
 practice, as their forms are not at all complex. But 
 the results afforded by photography are, as it is plain, 
 very superior. The photographic plate is indeed more 
 sensitive than the eye, and often allows us to see 
 details which had escaped the latter. Koch has given 
 good illustrations of pathogenic bacteria in his book 
 entitled, Beitrdge zur Biologie der Pflanzen, voL ii. 
 (1877). 
 
 Methods of Microbe Culture. The development of 
 microbes may be observed by placing the drop of 
 
264 
 
 MICKOBES, FERMENTS, AND MOULDS. 
 
 liquid to be examined in Ranvier's moist chamber, 
 consisting of a glass holder, with a circular groove and 
 a flat space in the centre. On the top is a cover-glass, 
 
 Fig. 103. Different forms of culture flasks employed by Pasteur (from Duclaux). 
 
 which is bordered with paraffin or vaseline, in order to 
 seal it. The groove contains air and a little liquid. 
 
LABORATORY RESEARCH, ETC. 
 
 265 
 
 The stage of the microscope is maintained at the 
 requisite temperature. 
 
 In order to make cultures in large quantities, other 
 kinds of apparatus are in use. The liquid supposed to 
 contain microbes is introduced into sterilized nutritive 
 liquids by means of a platinum wire, which has been 
 heated red hot and then allowed to cool; its end is 
 
 Fig. 104. Gas stove for the heating and 
 sterilizing of flasks. 
 
 Fig. 1 05. Pasteur's 
 culture tubes. 
 
 dipped into the liquid, and then instantly transferred 
 to the culture, while it is exposed to the heat of a 
 spirit-lamp. The flask is then sealed with a wad of 
 cotton wool. 
 
 The culture liquids employed by Pasteur are the 
 extract of beer-yeast, an infusion of hay, boiled and 
 neutralized urine, and the broth of various kinds of 
 
266 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 meat. The flasks are all modifications of the form 
 indicated in Fig. 76. These flasks are heated in an 
 iron gas stove (Fig. 104), of which the double case is 
 heated by gasburners, and it contains a basket of iron 
 wire as the receptacle of the flasks, tubes, etc., which 
 
 Fig. 106. Stand, bearing culture tubes. 
 
 are to be sterilized. The temperature, regulated by a 
 thermometer, must rise to from 1 50 to 250. 
 
 The nutritive liquid is boiled in a porcelain cru- 
 cible in the open air, and is introduced by breaking 
 off the tapered end of the flask ; it is then instantly 
 plunged into the broth, and drawn by an aspiration 
 through the opposite tube, after which the tapered 
 end is resealed at the lamp. 
 
LABORATORY RESEARCH, ETC. 267 
 
 The tubes, which have two reservoirs and two 
 tapered ends (Figs. 105, 106), are very numerous in 
 Pasteur's laboratory. They are ranged on a stand in 
 the way shown in the figure. 
 
 It is ascertained that the contents of the tubes are 
 really sterilized by leaving them for several days in 
 a stove which is maintained at a temperature of 35. 
 
 In addition to the culture liquids already indi- 
 cated, many others consist of various solutions of 
 phosphates of lime and potassium, albuminous solu- 
 tions, etc. 
 
 Solid Nutritive Substances. In order to isolate the 
 different species of bacteria, and to obtain pure cul- 
 tures, solid substances are now preferred : eggs, slices 
 of potatoes and carrots, but especially gelatine and 
 gelose which comes from Japan ready for use, and is 
 said to be extracted from a marine alga and the gela- 
 tinized serum of the blood of oxen. All these sub- 
 stances are transparent, so that the cultures can be 
 easily observed in glass tubes. Koch, in his Berlin 
 laboratory, makes almost exclusive use of solid media, 
 which are first sterilized by similar precautions. 
 
 In order to obtain pure cultures, all kinds of germs 
 are first allowed to grow ; then a very small amount 
 of them is taken from the culture medium, and 
 transferred to the sterilized medium, in which fewer 
 microbes naturally appear. After several repetitions 
 of this transplantation, sufficiently pure cultures may 
 generally be obtained within a short time. 
 
 Of THB 
 
 'UNIVERSITY; 
 
268 MICROBES, FERMENTS, AND MOULDS. 
 
 Koch employs a more certain method. He makes 
 his sowings on glass plates, covered with sterilized 
 gelatine and kept at a temperature of 30, by means of 
 a slender platinum wire which has been made red hot, 
 then allowed to cool, and charged with a very minute 
 particle of matter, which is full of bacteria. The 
 colonies of different microbes isolate themselves, and 
 may be plainly seen on the glass plate with the aid of 
 a magnifier. Their variable size and characters often 
 enable ; experienced observers to distinguish them by 
 their aspect alone (Fig. 87, 1, 2). The test-tubes, 
 containing sterilized gelatine, are then inoculated 
 with the microbe which it is desired to study (Figs. 
 82, 105), after taking the usual precautions. 
 
 The filters used to sterilize liquids are of Sevres 
 biscuit-ware heated to 120, or unglazed pottery. 
 Such is the Chamberland filter already described. 
 
 Cultures for Experiments on Animals. The pro- 
 cesses we have just indicated are also necessary in 
 these experiments. Here likewise all the causes of 
 error which would arise from the want of cleanliness, or 
 from the impurity of the culture liquids, must be care- 
 fully avoided ; and it must also be ascertained that 
 the effect produced on the animal is not due to any 
 other microbe than that of the experiment, nor to 
 any irritating and septic substance. The experiment 
 should be repeated several times by taking some of 
 the blood of the inoculated animal, and making a pure 
 culture, which may be used to reproduce the disease 
 in other animals. 
 
LABORATORY RESEARCH, ETC. 269' 
 
 Attenuation of Pathogenic Microbes. Successive 
 cultures have established, as we have seen, the pos- 
 sibility of attenuating virus, and transforming it into 
 vaccine. The processes employed to attain this object 
 are complex and varied, according to the species of 
 bacterium with which we have to do. 
 
 Thus, for fowl-cholera, Pasteur found that cultures 
 dating from fifteen days, or from one, two, eight, and 
 ten months, progressively lost their virulence, and he 
 believes this attenuation to be due to the action of the 
 oxygen of the air. So, again, Koch supposes that the 
 action of the air and the desiccation of the germs 
 produces, after a time, the natural extinction of the 
 disease. 
 
 Toussiant and Chauveau attenuate the virus of 
 anthrax, as we have seen, by subjecting it to a tem- 
 perature of from 42 to 43. Pasteur and Thuillier have 
 attenuated the virus of swine fever by passing it 
 through the system of a rabbit. Pasteur has also 
 attenuated the virus of rabies, of which the microbe 
 is still unknown, by passing it successively through 
 the systems of a rabbit, monkey, etc. 
 
 Finally, the same result may be obtained by add- 
 ing various antiseptic substances to culture liquids, 
 and thus weakening the virulent action of the 
 microbe. 
 
 Vaccination and Inoculation. The attenuated 
 virus or vaccine thus obtained may be used for inocu- 
 lation in quantities which experience indicates to 
 
270 MICROBES, FERMENTS, AND MOULDS. 
 
 be necessary and sufficient, quantities which vary 
 according to circumstances. In order to vaccinate 
 a sheep against anthrax, the animal must be held by 
 its fore feet in a sitting position, so as to present its 
 belly to the operator ; the tube of a Pravaz syringe, 
 containing the injection, is then inserted in the base 
 of the groin, which is devoid of wool. In cattle the 
 operation is performed at the root of the tail. It is 
 performed twice first with a weak vaccine, and, after 
 the lapse of a week, with one which is stronger. 
 
 Every one is acquainted with the process of vacci- 
 nating the human subject against small-pox, which 
 may be done either with lymph from an infant or 
 from a calf. A lancet or grooved needle is employed, 
 on which there is a drop of lymph, and five or six 
 punctures are made on the arms or thighs. 
 
 We must not imagine that vaccination can become 
 an absolute preservative from all diseases. For in- 
 stance, in erysipelas, pneumonia, and gonorrhrea 
 a first attack is so far from warding off a second 
 attack of the same disease, that it creates a favourable 
 field for relapses. It may, consequently, be assumed 
 a priori that vaccination in such cases would do more 
 harm than good (Cornil). It is the same with inter- 
 mittent fever, tuberculosis, syphilis, etc. ; all diseases 
 by which the same individual may be attacked several 
 times, and at varying intervals of time a clear proof 
 that the first attack has created no immunity against 
 subsequent attacks. 
 
LABORATORY RESEARCH, ETC. 271 
 
 Immunity. : This term is applied to the property 
 which the organism may acquire of being safe from 
 attacks of certain diseases due to microbes, either in 
 consequence of a former attack, or from a condition 
 which doubtless arises from absorbing the pathogenic 
 poison in minute doses, often repeated. Acclimatization 
 frequently constitutes immunity. Thus, in countries 
 where malaria, yellow fever, etc., prevail, the inhabi- 
 tants are less apt to contract the disease than 
 strangers. Such immunity is not absolute, and may 
 be lost in course of time. This has been ascertained 
 in the case of small-pox, so that it is prudent to be 
 revaccinated every ten or twelve years. 
 
272 MICROBES, FERMENTS, AND MOULDS. 
 
 CHAPTER VIIL 
 
 POLYMORPHISM OF MICROBES. 
 
 MICROBES (bacteria, ferments, and moulds) display, 
 like all the lower types of the animal and vegetable 
 kingdoms, considerable polymorphism. It is necessary, 
 therefore, that we should be on our guard, lest this 
 phenomenon should be the source of errors and con- 
 fusions very prejudicial to science, either by describing 
 as distinct species different forms of the same species, 
 or by being, on the other hand, led to regard as one 
 and the same species several which are really distinct, 
 and which for want of proper precautions, have been 
 brought together in the same preparation, without the 
 observer being aware of the fact. 
 
 We have indicated in the foregoing chapter the 
 scrupulous care which is indispensable in laboratories 
 in order to guard against surprises of this kind. 
 These precautions are not always sufficient, and ex- 
 perience shows that a single act of forgetfulness or 
 distraction on the part of the observer is enough to 
 spoil the result of a long series of researches. More- 
 
POLYMORPHISM OF MICROBES. 273 
 
 over, these precautions often afford only a negative 
 result, since some bacteria which have been reproduced 
 for a long while in the same form in a given medium 
 of culture, suddenly change their form and habits on 
 being transferred to another medium. 
 
 In order to give an idea of the difficulties which 
 beset this branch of research, it will be enough to 
 cite the history of lichens, a history well known to all 
 cryptogamous botanists. The structure of these lower 
 plants is at once simple and complex, since we may 
 regard them as formed by the association, or symbiosis, 
 as it is technically called, in each lichen of a species 
 of green alga with a species of colourless fungus of the 
 Ascomycetes group. 
 
 De Bary and the botanists of his school, Schwen- 
 dener, Bornet, Reess, Stahl, etc., state that in what 
 is called a lichen the tissues of an alga and those of 
 a fungus are intermingled in such a way as to form 
 the structure which constitutes the lichen. Owing 
 to this close association, a lichen can live like other 
 plants, not as a parasite, like fungi : the green parts 
 of the alga assimilate the carbon contained in the 
 air in the form of carbonic acid, and thus supply 
 nutriment to the fungus, which is consequently 
 regarded as a sort of parasite to the alga. In return, 
 the fungus supplies its mycelium to the lichen, by 
 which the latter is enabled to fasten on the surface of 
 rocks or trees. 
 
 This attractive theory was in favour for a con- 
 19 
 
274 MICROBES, FERMENTS, AND MOULDS. 
 
 siderable time. It is now almost completely abandoned, 
 and recent researches, made with the view of isolating 
 the alga and fungus which were supposed to co-exist 
 in the lichen, tend more and more to show that the 
 lichen is an independent plant, and not merely an 
 association of two plants of distinct families, algae and 
 fungi. 
 
 Errors of the same kind may occur in the study 
 of microbes, which, from their minute size, their 
 unicellular nature, the rapidity of their growth, the 
 variety of their habitat, and the great resemblance 
 of their form, are still more difficult to distinguish 
 than lichens. Of this we will give some examples. 
 
 Polymorphism of Leptothrix bucc'dis. Robin 
 (1866-1873), after studying the development of 
 Leptothrix, stated that this microbe first appears in 
 the form of a micrococcus ; then of a moving bacterium, 
 resembling B. termo, B. lineolum, etc., and finally it 
 forms the long immovable rod (bacillus), which consti- 
 tutes Leptothrix buccalis. This mode of evolution, 
 supposed to be usual in the genera Bacillus and 
 Leptothrix, is probably exact, and, with some reserve 
 as to the specific identity of the different forms 
 observed by Robin, modern micrographists are dis- 
 posed to accept it. But Robin goes further: he 
 regards the anthrax bacillus as specifically identical 
 with Leptothrix buccalis. The recent progress of 
 science no longer permits us to allow this identity. 
 We have seen that there are, at any rate, two 
 
POLYMORPHISM OF MICROBES. 275 
 
 species, quite distinct in their action upon men and 
 animals. 
 
 Polymorphism of Moulds. The comparatively 
 early researches of Hallier and others tend to show 
 that the fungi of moulds display considerable poly- 
 morphism, so as to completely overthrow the classi- 
 fication of these cryptogams. These researches have 
 been recently resumed by Coca rd as, who considers 
 it proved that all the moulds found in saccharine 
 liquids which have been allowed to ferment and in 
 pharmaceutical extracts belong to one and the same 
 species, which is highly polymorphic, and which he 
 terms the Penicilliuin ferment. Cocardas asserts that 
 he has seen this Penicillium ferment pass through 
 the following successive stages : Corpuscular (Micro- 
 coccus}, bacteridian (Bacterium, Bacillus), zooglairian 
 (colonies, or zoogloea), submerged hyphae (torula, 
 chaplets, or chains), fructiferous filaments (endogenous 
 spores), the whole constituting the algous phase of the 
 cryptogam which floats on the surface of syrup. 
 
 The fungoid phase then begins. The swellings 
 formed on the surface of the liquid by the endogenous 
 spores bud ; these buds become elongated, partitioned, 
 and ramified, constituting the aerial mycelium on 
 which the aerial fructifications are developed, which 
 can only form outside the liquid. 
 
 These fructifications, although all issuing from the 
 same mycelium, may present either the form of asper- 
 gillus, of mucor, or of penicilliuin, according to the 
 
276 
 
 MICROBES, FERMENTS, AND MOULDS. 
 
 nature of the spores on the fructiferous hypha. In 
 other words, the characters which have been hitherto 
 considered as proper to the three genera, Aspergillus, 
 Mucor, and Penicillium, themselves types of three 
 Very distinct families, are found either simultaneously, 
 
 Fie 107 The penicillium ferment (Cocarda*). Aerial fructific-tion in ey tract of 
 liquorice: the three forms, Mucor (1), Penicillium (2), Aspergillus (3j, borne .y 
 a single bypha A (x 225 diaiu.)- 
 
 or successively, on the same hypha, and are only 
 varied forms of a highly polymorphic species, the 
 penicillium ferment (Cocardas). 
 
 Fig. 107 represents the three forms of fructifica- 
 
POLYMORPHISM OF MICROBES. 277 
 
 tion, as Cocardas states that he has seen them, united 
 and borne by a single hypha, magnified 225 diameters. 
 
 Each form of Penicillium belongs to a special 
 change in the syrup. In syrup which has become 
 turbid, the ferment is in the corpuscular or bac- 
 teridian stage; when the syrup is ropy, it is in the 
 zooglairian or filamentous stage; when it has turned 
 sour, it is in the stage of; aquatic fructification ; 
 finally, when the syrup is mouldy, it is in the stage 
 of aerial fructification. 
 
 Cocardas states that he has observed this really 
 astonishing polymorphism while making use of the 
 ordinary precautions for averting gross errors. Not- 
 withstanding facts of the same kind, which have been 
 put forward previously, notably by Hallier, but which 
 are frequently contradicted by more accurate research, 
 it may be asked whether this is not merely a pheno- 
 menon of confusion, analogous to that which was 
 rightly or wrongly supposed to exist in the case of 
 lichens. Fresh researches, made with greater pre- 
 cision in sterilized liquids, and accompanied by the 
 most scrupulous precautions, are necessary before 
 these facts can be definitively accepted by science. 
 
 Polymorphism of Fungi of the Human Skin. It 
 is more easy to accept, at any rate in part, the poly- 
 morphism recently noted by Grawitz in the fungus 
 of 'Favus (ringworm), which we have already de- 
 scribed under the name of Achorion Schoenleniir. , 
 
 Grawitz asserts that Achorion Schoelenii of ring- 
 
278 MICROBES, FERMENTS, AND MOULDS. 
 
 worm, Trichopkyton tonsurans of cirinnate herpes, and 
 Microsporon furfur of variegated pityriasis, are only 
 different forms of one and the same parasite, of which 
 he has made a successful culture on gelatine, repro- 
 ducing its successive appearances. 
 
 Grawitz, however, goes further than many micro- 
 graph ists will consent to follow him. He asserts that 
 all the fungi of the human skin are only trans- 
 planted forms, modified by the medium, of Oidium 
 lactis, the white mould found on milk, bread, paste, 
 potatoes, etc. 
 
 So, again, Ofrtium albicans, the fungus of thrush, 
 is, as we have said, specifically identical with Sac- 
 charomyces mycoderma, or flowers of wine, a ferment 
 which is developed on the surface of liquids which 
 are acid and contain little sugar. This must not be 
 confounded with Mycoderma aceti, a true bacterium, 
 causing the acid fermentation of wine and beer. 
 
 Still more recently, in 1883, Malcolm Morris and 
 G. C. Henderson have stated that in an artificial 
 culture of peptonized gelatine at the temperature of 
 from 15 to 20, spores of Trichophyton tonsurans were 
 developed, forming ramified hyphse which were after- 
 wards covered with fructifications resembling those of 
 Penicillium. 
 
 Injections of Mould-spores into the Blood. Grawitz 
 injected spores of Penicillium and Aspergillus into 
 the vascular system of rabbits, with the view of 
 demonstrating their transformation into bacteria. He 
 
POLYMORPHISM OF MICROBES. 279 
 
 thus obtained the formation of small metastatic 
 centres in the kidneys, liver, lungs, etc. The spores 
 sent forth hyphse which were able to produce im- 
 perfect organs of fructification, but failed to effect 
 the formation of fresh spores. Gaffky, Koch, and 
 Leber repeated these experiments, and showed that 
 the acclimatization of any kind of mould in the 
 interior of the system was impossible, whatever might 
 be the more or less serious lesions produced by the 
 introduction of foreign bodies into the blood of a 
 warm-blooded animal. 
 
 Errors caused in Laboratory Experiments by the 
 Involuntary Mixture of Different Microbes. We 
 should be the more cautious about accepting the real 
 or apparent polymorphism of certain microbes, since 
 the most scrupulous precautions do not always suc- 
 ceed in preventing confusion. Of this Klein gives 
 the following instances. 
 
 While he was studying the microbe of anthrax in 
 his laboratory at the Brown Institution, one of his 
 friends was studying canine distemper in an adjoining 
 room. This friend injected the blood of a dog affected 
 by distemper into a guinea-pig's veins, and was sur- 
 prised to see the animal die two days later with all 
 the symptoms of anthrax, and to discover Bacillus 
 antkracis in its blood. Yet he had made the injec- 
 tion with a perfectly new hypodermic syringe ; while 
 Klein, for his own injections, had made exclusive use 
 of pipettes drawn to a point in the flame of a lamp, 
 
280 MICROBES, FERMENTS, AND MOULDS. 
 
 In this case, it must be assumed that the bacilli arid 
 spores of anthrax had settled on Klein's clothes, had 
 spread to the table and floor of the second cabinet, 
 and had passed thence on to the guinea-pig's hair 
 at the moment of the experiment. 
 
 Another operator, who inoculated a guinea-pig 
 with human tubercles, worked at the same table as 
 that on which Klein performed his experiments on 
 anthrax. Two of the guinea-pigs died with Bacillus 
 anthracis in the blood. Yet the pipettes in use had 
 always been repointed in the fire, and all the other 
 instruments "had been thoroughly heated before the 
 inoculation. 
 
 In another case, on the contrary, a guinea-pig 
 inoculated with an attenuated culture of Bacillus 
 anthra.cis, of which the effect could not be fatal, was 
 examined at the end of some weeks, and all its organs 
 were found to be affected by the bacilli of tuberculosis. 
 On consulting his notes, Klein found that on the same 
 day he had performed experiments on tubercular 
 matter in the same laboratory, but he had always 
 been careful to use different instruments. The same 
 phenomenon was produced in a rabbit which died, not 
 of anthrax, with which he was supposed to have been 
 inoculated, but of general tuberculosis. The inocu- 
 lating liquid had clearly been impure. 
 
 It is probable that Biichner's experiments on the 
 bacillus of meat were vitiated by a similar error. 
 Biichner inoculated mice with this bacillus. and believed 
 
POLYMORPHISM OF MICROBES. 
 
 -that he had produced anthrax. But as he had per- 
 formed numerous experiments on anthrax in the same 
 laboratory, it is probable that his cultures of the meat 
 bacillus were impure, and that he had really inoculated 
 with. B. anthracis. The transformation of the bacillus 
 of meat into that of anthrax is therefore not yet 
 proved. 
 
 1 Jequirity Microbe. This is another instance of an 
 analogous mistake, owing to which the Jequirity 
 bacillus has baen r supposed to be transformed from a 
 merely septic into a pathogenic microbe. This sub- 
 stance, recently imported from India, is extracted from 
 the seeds o Abrus precatorius, one of the leguminous 
 plants. A few drops of the infusion of these seed,s 
 applied to the eye produce conjunctivitis,, which is 
 artificially excited in order to effect the disappearance 
 of the granules (trachoma) -by which the inner surface 
 of the eyelids is sometimes affected. In India, the 
 same liquid is used to kill cattle by a simple puncture, 
 with the object of skinning them. 
 
 When Sattler noticed that an infusion of Jequirity 
 became full of moving bacilli in a few hours, re- 
 sembling bacillus subtilis of an infusion of hay (Fig. 
 80), he made cultures of this bacillus, and produced 
 by their means serious ophthalmia in the eyes of 
 rabbits. At the same time he ascertained that this 
 microbe was harmless when floating in the -air, and 
 that its pathogenic properties were only displayed 
 tvhen it was cultivated in an infusion pf Jequirity. 
 
282 MICROBES, FERMENTS, AND MOULDS. 
 
 In spite of this, Sattler ascribes the pathogenic action 
 of this substance to the microbe. 
 
 Klein repeated his experiments with great care, 
 and was successful in solving the contradictions which 
 
 O 
 
 appeared to result from Sattler's researches. He 
 proved that the bacillus of jequirity, taken by itself, 
 could no more produce an infectious ophthalmia than 
 Blichner's meat bacillus could produce anthrax. The 
 poisonous principle of jequirity is a chemical ferment 
 (Abrine), analogous to pepsine, and independent of 
 any microbe, and its assumed bacillus probably does 
 not differ specifically from Bacillus subtilis. 
 
 The transformation of an originally harmless mi- 
 crobe into a pathogenic microbe is therefore not yet 
 proved, and all known facts contradict the possibility 
 of such a transformation. 
 
 Septic and Pathogenic Microbes. Hence we are 
 led to define, more precisely than before, the terms 
 septic microbes and pathogenic microbes, which are 
 in current use in bacteriology. 
 
 The term " septic " is applied to the microbes or 
 bacteria which generally live in decomposing organic 
 matter and in dead bodies. These microbes, or their 
 spores, are found in the air, in water, or the soil, in 
 the mouth and intestinal canal of a healthy man or 
 animal; but they are developed in greater number* 
 when the tissues are dead or in a diseased condition, 
 and also in pus, in the bronchial secretion of pulmonary 
 catarrh, on the surface of intestinal ulceration, etc. 
 
POLYMORPHISM OF MICROBES. 283 
 
 Such are Bacterium termo and Bacillus subtilis, the 
 microbes of putrefaction, those of the sweat of feet, 
 etc., of which we have spoken above; such, again, is 
 the bacillus of Biichner's meat infusion, that of Sattler's 
 jequirity, and finally, Grawitz's Aspergillus, mentioned 
 in this chapter. 
 
 These yarious microbes, inoculated or injected into 
 blood, may indeed produce different disorders, which 
 in some cases always remain local (oedema) ; in others 
 are limited to metastatic centres encysted in various 
 organs the liver, kidneys, lungs, etc. ; or, again, they 
 may produce a general infection of the blood, as in the 
 septicemia produced by Davaine when he inoculated 
 rabbits with the fluid of putrid beef. These rabbits 
 died within two days, and their blood was found to 
 be full of Bacterium termo. The same result has been 
 obtained by Pasteur and Koch, by merely inoculating 
 guinea-pigs and mice with a little putrid earth or 
 water, in which the same organism was evidently 
 present. But in no case a disease with distinct cha- 
 racters was produced by this means, with special 
 symptoms, epidemic or contagious, analogous to those 
 of erysipelas, anthrax, tuberculosis, or cholera. Hence 
 the name of experimental septicemia, since these 
 diseases do not exist in nature. 
 
 On the other hand, those microbes are termed 
 pathogenic which always characterize by their 
 presence a special disease, epidemic or contagious, and 
 possessing special symptoms and lesions, whether this 
 
284 MICROBES,. FERMENTS, AND MOULDS. 
 
 microbe subsists in the blood, the inner part of the 
 organs, or merely on the surface of the digestive canal. 
 ,Such are the microbes of anthrax, of tuberculosis, and 
 : of cholera-, natural diseases which are not produced by 
 the experiments of man. Up to this time a septic 
 microbe has not been proved to be transformed into a 
 truly pathogenic microbe and consequently a com- 
 pletely new djj&ease, characterized by the development 
 of this .microbe in the body of man or animals, has 
 not been cheated. 
 
 It must also be . remarked and this peculiarity is 
 common/to both classes of microbes that certain 
 bacteria produce very different effects, according to 
 the animals into whose bodies they are introduced. 
 (Thus guinea-pigs cannot be inoculated with the 
 , experimental septicemia of rabbits and mice ; and 
 dogs and swine display more or less resistance to the 
 inoculation of anthrax. Finally, there are cases in 
 which the attempt to. inoculate an animal with a 
 - contagious disease merely produces a septicemia 
 which must not be confounded with it. This result 
 will not astonish those who know that some species 
 of plants, poisonous to man, can be eaten with im- 
 punity by many animals. But it is well to keep 
 this fact in mind in laboratories, when the attempt 
 is made to inoculate animals of various species. 
 
CHAPTER IX. 
 
 CONCLUSION. a 
 
 THE MICROBIAN THEORY COMPARED WITH OTHER 
 THEORIES PUT FORWARD TO EXPLAIN THE 
 ORIGIN OF CONTAGIOUS DISEASES. 
 
 THE parasitic theory of diseases is far from being 
 generally adopted by medical men; at this very time 
 the theory is actively opposed by medical practitioners 
 of high standing,, who are advocates of the theory of 
 the innate character of diseases. In their opinion, the 
 disease is spontaneously developed in the patient, or, 
 at any rate, under the influence of a contagion of 
 which the nature is still unknown. They consider that 
 it is only a secondary complication when microbes are 
 found in the blood, and that these microbes are not 
 the cause of the disease, nor even the contagious 
 element, nor the vehicle of contagion. In a word, 
 the microbian theory is in their eyes a purely gratuitous 
 hypothesis. 
 
 Admitting with them that the microbian theory is 
 
286 MICROBES, FERMENTS, AND MOULDS. 
 
 only an hypothesis, let us compare it with other hypo- 
 theses which have been proposed to explain the 
 virulent and contagious nature of certain diseases. 
 This comparison may throw some light on the question 
 at issue. 
 
 The value of an hypothesis must be estimated by 
 the number and importance of the facts of which it 
 affords a clear, precise, and really scientific explanation ; 
 it must also be estimated by its influence on the 
 a Ivance of science. We will therefore enumerate the 
 principal theories which have been proposed to explain 
 the origin of virulent and contagious diseases, without 
 the intervention of microbes. 
 
 Robins Theory of Blastema. Although, as far as 
 we are aware, Robin has not recently published any- 
 thing with reference to his opinion of the value of the 
 microbian theory, some of his pupils have set forth the 
 theory of blastema as it was stated by their master in 
 books published from ten to twenty years ago. 
 
 In Robin's opinion, no cell is born from another 
 cell, in the form of a bud, an egg, or a spore. Un- 
 doubtedly there is no spontaneous generation, at the 
 expense of elements of exclusively inorganic origin ; 
 but this generation or genesis occurs every day at the 
 expense of an organized substance which is living, 
 but fluid and amorphous, and which has its source 
 from other pie-existent cells. This fluid is termed 
 blastema by Robin. Blastema is the surplus of the 
 nutritive substance, organized by the cells and exuded 
 
CONCLUSION. 287 
 
 from them. New cells may be completely formed at 
 the expense of this blastema, without having their 
 source in one cell more than in another. According 
 to Robin's theory, the pus-corpuscles, which #re a new 
 creation, are produced in this way : they result from 
 the exudation of a fluid which issues from all the 
 organs, and are not produced by the enlargement, 
 reproduction, and budding of pre-existent cells, as it 
 is stated in other theories, and notably in those of 
 Schiff and Cohnheim. 
 
 When this is established, it follows that all diseases 
 have their origin in a chemical or physiological 
 change in the blastema, which at one time produces 
 normal cells, adapted to replace those which die from 
 natural decay, and at another engenders diseased cells, 
 which are dangerous, either owing to their too great 
 number, as in septicemia, or from their peculiar nature, 
 as in tubercle and cancer. Here we will quote Robin's 
 words : " The cause of morbid disturbance arises from 
 the changes which take place in the quantity and 
 nature of the immediate constituents of the actual 
 substance of the tissues and secretions. These changes 
 
 O 
 
 make the development of minute spores possible. The 
 multiplication of microscopic plants is a secondary 
 phenomenon; not the scientific cause which actually 
 determines it. The presence of the vegetable parasite 
 is a complication which has been mistaken for the 
 cause " (Ilistoire naturelle des vegetaux parasites de 
 I'hommt, 1853, p. 287) 
 
288 MICROBES, FERMENTS, AND MOULDS. 
 
 These words were written more than thirty years 
 ago, and it may be asked whether the immense pro- 
 gress which science has made since that date has not 
 somewhat modified the author's opinions. Jousset 
 de Bellesme is scarcely entitled to take these words 
 and paraphrase them as follows: "The microbe, 
 where it really exists, is only a secondary phe- 
 nomenon, and it would not be too much to say that 
 no fresh element has intervened, either in small- pox, 
 scarlatina, or tubercular disease ; in such cases there 
 is only an exaggeration and reproduction of normal 
 elements, which, influenced by wholly obscure con- 
 ditions, are evolved in an altogether unusual manner." 
 
 The definition given by Jousset de Bellesme is not 
 that of contagious diseases, but of those which are 
 combined under the generic name of cancer. If he 
 means to compare these diseases with cancer, such a 
 comparison is impossible. It is well known that 
 cancer is not contagious, and this fact alone places a 
 gulf between these two kinds of disease. Cancer is 
 not only not contagious nor is it conveyed by inocula- 
 tion, but it is only hereditary in about a tithe of 
 cases. . Tuberculosis is, on the other hand, a con- 
 tagious disease, because it is produced by microbes, 
 and it may be set down as hereditary in nine cases 
 out of ten. 
 
 Jousset de Bellesme's theory, therefore, explains 
 nothing, and leaves the question absolutely untouched, 
 since it throws no light on contagion and virulence, 
 
CONCLUSION. 289 
 
 the precise points which it is essential to explain. 
 But we must return to Robin's theory. When he 
 states that the microbe is only developed in tissues 
 which are already changed, Robin is not so far from 
 the parasitic theory as his pupils represent him to 
 be. It matters little that the microbe may be only 
 a complication, a secondary phenomenon, if this 
 secondary phenomenon dominates the whole disease 
 and invests it with its dangerous character, its con- 
 tagious and virulent nature. In the case of a viper's 
 bite, it is not the bite from the animal's teeth which 
 is dangerous, but the introduction of the venom 
 which flows from them; that is, the secondary 
 phenomenon. And it is the same with an anatomical 
 puncture. 
 
 Two men in similar circumstances are attacked by 
 pneumonia; the first will recover with ease because 
 he is only thirty years old, while the other is almost 
 certain to die because he is seventy-five, but we should 
 not therefore say that he died of old age, and that the 
 pneumonia was only a secondary phenomenon. 
 
 Oidium and the phylloxera have attacked the 
 French vineyards which are exhausted by excessive 
 cultivation, but it will not therefore be denied that 
 these are two dangerous diseases ; nor should we say 
 that they are secondary phenomena. It is therefore 
 evident that Robin's theory, as it is set forth by 
 his disciples, who have resuscitated statements made 
 twenty or thirty years ago, is no longer on a level 
 20 
 
290 MICROBES, FERMENTS, AND MOULDS 
 
 with the present state of science, and is in no case 
 applicable to virulent and contagious diseases. 
 
 Theory of Charlton Bastian, and the English Fol- 
 lowers of his School. This theory, held by the most 
 ardent opponents of the school of Tyndall and Pasteur, 
 is set forth in the writings of Lewis and Lionel Beale. 
 It scarcely differs from the one we have just stated. 
 Lewis thinks it very evident that the presence of 
 microphyta of the blood is only a secondary pheno- 
 menon; that the change in the fluids of the body is 
 effected before the slightest trace of their presence can 
 be discovered. This is plainly Robin's theory.* 
 
 Beale is still more absolute and exclusive.! He 
 holds that the solid particles of vaccine are not bacteria 
 nor inicrococci, but bioplasts, or formulated elements 
 which have their source in the living substance of the 
 cow, and these bioplasts constitute the effective con- 
 tagion of all virulent diseases. Bioplasts are extremely 
 minute particles of the living substance of the species 
 affected by the disease. The contagion is a bioplasma, 
 and each species of contagious bioplasma manifests its 
 peculiar specific action, and that only. We must 
 leave it to others to admire and paraphrase this scien- 
 tific jargon, which seems intended to take us several 
 ages back. We must, however, observe that Beale's 
 theory is somewhat allied to another, much more 
 serious and complete, of which we have now to speak. 
 
 * Les Microphytes du Sang, 1881. 
 f The Microscope in Medicine, 1882. 
 
CONCLUSION. 291 
 
 Bechamp's Theory of Microzyma. According to 
 this theory, diseases are not due to a fluid blastema 
 which is changed in disease, but to an organized and 
 solid blastema, resembling the constituents of the 
 blood, and consisting of very minute particles of living 
 matter, which are microzyma. These are the elemen- 
 tary granules which may be seen under the microscope 
 in the cells and in all the fluids of the organism. 
 The mycrozyma, and not the cells in which they are 
 encysted, are the real agents of all the functions of 
 the organism. By the secretion of a fluid termed 
 zymase, or ferment, by which they are constantly 
 surrounded (both together constituting what is called 
 protoplasm); these microzyma effect the various trans- 
 formations which have for their final object the nutri- 
 tion of the organism. Virulent and contagious diseases 
 are not produced by parasites coming from without, 
 but by the microzyma themselves, owing to a perver- 
 sion of their normal functions. In such cases they 
 secrete a vitiated zymase, and are transformed into 
 micrococci and bacteria, which it is an error to regard 
 as foreign bodies, since they are only the result of the 
 special form of microzyma pre-existing in our tissues. 
 
 It must also be said that these microzyma are im- 
 perishable. The cells of our organism die and are 
 renewed, but the microzyma which they contain are 
 only associated with other microzyma in order to 
 constitute fresh cells. After death, their transforma- 
 tion into microbes produces putrid fermentation, -and 
 
292 MICROBES, FERMENTS, AND MOULDS. 
 
 their existence is prolonged far beyond that of the 
 organisms of which they temporarily formed part. 
 Thus the microzyma of chalk, which doubtless have 
 their source in the animal and vegetable tissues of 
 that epoch, are still living after a repose of many 
 thousand centuries, and may be transformed into 
 bacteria if supplied with the fitting nutritive liquid, 
 as Bechamp has demonstrated. 
 
 This is undoubtedly a very attractive theory, 
 which would explain a larger number of facts than 
 the theories previously stated, yet it is impossible to 
 make it agree with some of these facts, while they 
 are readily explained by the parasitic theory. Such, 
 for example, are the phenomenon of putrefaction, and 
 the benefits of Lister's dressing, and of Guerin's pro- 
 tective method applied to wounds. 
 
 Robin, in his theory of blastema, also stated that 
 putrefaction took place without the intervention of 
 any external agent. 
 
 It is, however, now known that when dead bodies 
 are protected from air-germs, they do not putrefy, but 
 become mummies. Such is the case with the bodies 
 which have been preserved for many centuries in the 
 crypt of one of the churches in Bordeaux, and which, 
 without any antiseptic preparation, have gradually 
 passed into the state of mummies. Many underground 
 buildings and caverns, in which the air is dry and 
 the temperature invariable, present conditions favour- 
 able to such transformation, doubtless because this 
 
CONCLUSION. 293 
 
 situation is unfavourable to the life of the lower 
 plants. 
 
 The theory of microzy.ma explains the transmission 
 of diseases by the organized elements of the virus, 
 while the filtered liquid of the same virus is unin- 
 jurious, and in this respect it is more in accordance 
 with facts than the theory of blastema; but it does 
 not explain the effect of the exclusion or sifting of 
 the air by Gue'rin's dressing, nor that of carbolic acid 
 in Lister's dressing. In fact, if the virulent microzyma 
 are in the patient's body, and have no external source, 
 it is difficult to understand of what use this process 
 can be. It is evident that the cotton wool, which only 
 arrests the solid particles of the air, while admitting 
 the air itself, must act by warding off something 
 suspended in the air, and the matter in suspension 
 can only be organized bodies, or air-germs. 
 
 Theory of Ptomaines. Special alkaloids (septine) 
 were discovered by Panum in pus and by Selmi and 
 Gautier in putrefying matter (ptomaines), and par- 
 tizans of the theory of non-organized virus appeal to 
 these as a last resource. It has been supposed that 
 these ptomaines or toxic alkaloids were the product 
 of putrefaction, or morbid changes which were purely 
 chemical, produced in the tissues and fluids of the 
 system, without any external intervention of microbes. 
 This a priori idea does not really differ from Robin's 
 theory of blastema. If it is accepted, all pathogenic 
 microbes resemble Battler's jequirity bacillus, which 
 
294 MICROBES, FKRMENTS, AND MOULDS. 
 
 certainly lives and is developed in the toxic juice of 
 the seeds of Abrus precatorius, but which, as Klein 
 has shown, has no influence on the artificial conjunc- 
 tivitis produced by the aid of this liquid. 
 
 This theory of ptomaines without microbes is, 
 however, inconsistent with an impartial study of facts. 
 It is true that a suitable nitration will separate the 
 ptomaine from its microbe ; but the converse, as in 
 the case of the jequirity liquid, is impossible. When 
 this microbe is separated from the original liquid, 
 and transferred to the infusions of successive cultures, 
 so as to purify it from every foreign element, it 
 continues to produce its characteristic ptomaine, which 
 is manufactured completely at the expense of the 
 culture liquid, as Pouchet's recent experiments on the 
 ptomaine of cholera have shown. There is no ptomaine 
 without its. special microbe, any more than there is 
 ergotine without Claviceps purpurea, or vinegar 
 without Mycoderma aceti". 
 
 Pasteur s Microbian Theory is the only one which 
 explains all Facts. The microbian theory is the only 
 one which is not obliged to have recourse to the vague 
 expressions with which medicine was formerly content 
 to explain the contagion of diseases, and which still 
 satisfies Jousset de Bellesme, when he speaks of the 
 wholly obscure conditions which accompany the pro- 
 duction of these diseases. All the expressions of 
 miasmata, virus, effluvia, etc., which were in use twenty 
 years ago to designate that unknown agency which 
 
CONCLUSION. 295 
 
 constitutes contagion, could only be denned by having 
 recourse to the term " catalytic action," which merely 
 placed the solution of the problem another step back, 
 and substituted one unknown thing for another.* The 
 parasitic theory will have done much for science if it 
 only delivers us from " miasmata," " effluvia," and, 
 above all, " catalytic action." As soon as it had been 
 shown that miasmata and effluvia, as well as virus, were 
 only air-germs that is, microbes and their spores a 
 brilliant light was thrown on all pathology, of which 
 the benefits may be measured by the great work accom- 
 plished in this direction within the last ten years. 
 
 This theory has given us Guerin's protective treat- 
 ment of wounds, Lister's antiseptic dressing, and 
 Pasteur's new vaccine, and these three great dis- 
 coveries are enough to render the hypothesis immortal, 
 even admitting that it is only an hypothesis. The 
 adverse theories, when opposed to the microbian 
 theory, can show us no progress effected in science, 
 and this suffices to condemn them. 
 
 Moreover, the microbian theory is no longer in 
 the primitive stage in which it can be regarded as 
 a pure hypothesis, since it has entered the domain 
 of positive facts. Before an infectious disease can be 
 considered due to the presence of a specific microbe, 
 
 * See, for example, the article Miasmes in Nysten's Dictionary 
 (Litire and Itdbin, edit. 1864): "Miasma is constituted by the organic 
 substances of the air, in different stages of catalytic modification." These 
 words arc printed in italics by Robin himself. See also the words 
 Ejjluvesj Catalytiques, Virus, etc., in the same dictionary. 
 
296 MICROBES, FERMENTS, AND MOULDS. 
 
 it is indispensable to submit it to the test of the four 
 following rules, which have been clearly established 
 by Koch : 
 
 1. The microbe in question must have been found 
 either in the blood or tissues of the man or animal 
 which has died of the disease. 
 
 2. The microbe taken from this medium (the 
 blood or tissues, whichever it may be), and artificially 
 cultivated out of the animal's body, must be trans- 
 ferred from culture to culture for several successive 
 generations, taking the precautions necessary to 
 prevent the introduction of any other microbe into 
 these -cultures, so as to obtain the specific microbe, 
 pure from every kind of matter proceeding from the 
 body of the animal whence it originally came. 
 
 3. The microbe, thus purified by successive cultures, 
 and reintroduced into the body of a healthy animal 
 capable of taking the disease, ought to reproduce the 
 disease in question in that animal with its charac- 
 teristic symptoms and lesions. 
 
 4. Finally, it must be ascertained that the microbe 
 in question has multiplied in the system of the animal 
 thus inoculated, and that it exists in greater number 
 than in the inoculating liquid. 
 
 These four conditions are necessary and sufficient, 
 and in the present state of science they may be 
 regarded as fulfilled in a considerable number of 
 diseases: in anthrax, fowl cholera, swine fever, 
 glanders, small-pox, tuberculosis, erysipelas, and even 
 
CONCLUSION. 297 
 
 in Asiatic cholera. These,, are undoubtedly microbe 
 diseases in every sense of the term. 
 
 The opposition which the microbian theory 
 encounters in pathology is not new, and need not 
 surprise us. In all ages medicine has clung to its old 
 traditions, and has been unwilling to renounce the 
 habit of regarding disease as something mysterious, 
 just as in the times of ancient magic, of which our 
 modern seers and sorcerers are a relic. The parasitic 
 theory is too simple and natural to be accepted without 
 a struggle, but its earlier achievements are a good 
 omen for the future. We need scarcely remind our 
 readers that at the beginning of this century the 
 parasitic theory of itch encountered the same opposi- 
 tion, yet no physician now doubts that Sarcoptes 
 scabiei is the sole cause of the disease. Somewhat 
 later, towards the middle of the century, when the 
 presence of special microphyta was ascertained in 
 most skin-diseases, the importance of this discovery 
 was denied; yet few physicians will now dispute 
 that these microphyta are the chief, or rather the 
 sole cause of these diseases. 
 
 So, again, in anthrax, when we observe the blood 
 and all the organs filled with bacteridia (Bacillus 
 anthracis), it can hardly be denied that this disease 
 is essentially parasitic. Since these bacteridia are 
 living beings which grow, are reproduced, and breed 
 with great energy, it must be admitted that their 
 presence constitutes an immediate danger, especially 
 
298 MICROBES, FERMENTS, AND MOULDS. 
 
 since it is known that they elaborate, at the expense 
 of the organism, a violent poison (ptomaine); which 
 penetrates wherever the bacteridia cannot find their 
 way. It can hardly be said that in this case the 
 bacteridia are only a " secondary phenomenon ; " that 
 is, an unimportant complication which gives no cause 
 for uneasiness. 
 
 What we have here said of anthrax also applies 
 to other diseases : to diphtheria, small-pox, and inter- 
 mittent fever. We venture to say that if our instru- 
 ments were not sufficiently powerful to enable us to 
 see the organisms which cause these diseases, reason 
 alone would oblige us to admit their existence, from 
 our general knowledge of the cause and nature of 
 contagious diseases. The word "contagion" implies 
 microbe, and the simplicity of the theory gives it 
 value, and permits us to regard it as the expression 
 of actual facts. 
 
 After this, it is unimportant to know whether the 
 microbe is itself the contagion, or only its vehicle ; if 
 it acts by itself, or only by the production of ptomaine ; 
 if there is a specific microbe for each kind of disease, 
 or if this microbe is susceptible of transformation, like 
 other living things, according to the nature of the 
 medium in which it is nourished. These are secondary 
 questions, of which the future will doubtless afford the 
 solution, but which do not affect the principle of the 
 parasitic theory. That theory is only just established ; 
 each day brings a fresh stone to the edifice, but we 
 
CONCLUSION. 299 
 
 must not yet expect it to be complete in all its parts. 
 The advance of science may modify its details, but it 
 may be asserted that the foundation itself will remain, 
 since it relies on the simple and natural interpretation 
 of facts. 
 
APPENDIX. 
 
 TERMINOLOGY OF MICROBES : VARIATIONS IN DENOMINATION 
 AND CLASSIFICATION. 
 
 IN consequence of the polymorphism of microbes, the 
 terminology employed by different authors is very unstable. 
 We have given the established morphological classification 
 which is still most generally used, but we must here add 
 some remarks which will make it more easy to understand 
 the works recently published on microbes, such as Les 
 Bacteries, by Cornil and Babes, and Micro-organisms and 
 Diseases, by Klein. 
 
 We must first note the tendency to eliminate the names 
 of two genera : Bacterium and Vibrio. 
 
 Cornil and Babes give the name Bacteria, which is the 
 title of their work, to the whole group of Bacteriacece, or 
 microbes strictly so called, regarded as a distinct order. 
 They have consequently been led to suppress the genus 
 Bacterium, in order to avoid confusion ; and most of the 
 species formerly assigned to the genus Bacterium are 
 regarded by them as Bacillus, whether the individual is 
 long or short, mobile or stationary. In the description 
 of the microbes of human diseases, we have conformed 
 
302 APPENDIX. 
 
 to this nomenclature, which appears to be adopted by 
 histologists, so as not to overload the synonymy of 
 microbes, which is already somewhat encumbered. It is 
 probable, moreover, that this assimilation is correct, 
 and that most bacilli pass through a phase in which they 
 are short and mobile, before becoming elongated and 
 stationary. On the other hand, certain types of the old 
 genus Bacterium for instance, the bacteria in the form of 
 an 8 should rather be assigned to the genus Micro coccus, 
 or to the new genus Diplo coccus. 
 
 With respect to the genus Vibrio, it seems to have 
 been originally only a somewhat heterogeneous collection, 
 comprising both the chains and chaplets of micrococci or of 
 short bacteria, and the strictly unicellular organisms which 
 might be assigned to the genus Spirillum. Klein, how- 
 ever, reserves this genus for Vibrio rugula and V. Serpens. 
 
 The genus Hicrococcus (Hallier) is also termed by 
 Cohn, Spherobacterium, and these two names are now 
 given to the only unicellular microbes which are round 
 or oval, stationary, and consequently devoid of cilium or 
 flagellnm, the organ of propulsion. 
 
 These micrococci may be in the form of chains or 
 chaplets (torula), dumb-bells (Klein), the figure 8 (Diplo- 
 coccus, Billroth), groups of four, and zoogloeae or in masses 
 of greater numbers. 
 
 The genus Bacterium (Microbacterium, Cohn) differs 
 from the foregoing, as Klein states, chiefly in the oval or 
 cylindrical form of its cells, and still more by the presence 
 of a cilium or flagellum at one extremity, which gives a 
 spontaneous movement. They may thus assume the form 
 ot: a sponge-cake and of a dumb-bell when they divide in 
 two, and may also form short chains or zoogloeas. As we 
 Lave already said, most of these organisms are assigned 
 
UFITBISIT7 
 
 303 
 
 by Cornil to the genus Bacillus; at any rate, in the case 
 of organisms peculiar to human diseases. 
 
 The genus Bacillus, according to Klein (Desmobac- 
 terium, Cohn), includes microbes in the form of more or 
 less elongated rods, which divide by fission into straight, 
 curved, or zigzagged chains, formed of elements generally 
 in contact by their square-cut edges, and which, may be 
 considerably elongated in the form of Leptothrix. 
 
 Some of these, when isolated or in short chains, pos- 
 sess a flagellum at one extremity, and are consequently 
 mobile such is the case with Bacillus subtilis and most 
 of the bacilli of putrefaction but they lose this organ 
 of movement on passing into the state of Leptothrix. 
 Bacillus antliracis is always stationary, and devoid of 
 flagellum. The fact that there is in this genus a vibratory 
 cilium, and consequently motion, breaks down the barrier 
 between the genera Bacterium and Bacillus^ and con- 
 sequently justifies Cornil's view. 
 
 The genera Spirillum (Spirolacterium, Cohn,) and 
 Spirochoete are much more rare, and have not given rise 
 to the same variations in nomenclature. 
 
 We conclude by reproducing the classification of 
 Rabenhorst and Fliigge, as it is given by Cornil and 
 Babes, in order to serve as a convenient scheme for the 
 pathogenic bacteria iu which we are specially interested : 
 
304 
 
 APPENDIX. 
 
 CLASSIFICATION OF RABENHORST AND FLUGGE. 
 
 GEKEEA. 
 
 10VUMK 
 
 In large numbers 
 
 JUtC/ UWVVMMB 
 
 Round 
 
 and 
 
 
 or 
 
 /Solid colonies Regular colonies 
 
 Ascococcus. 
 
 oval 
 cells. Forming 1 -JjrSi. In small definite 
 zoogloeajj numbers 
 
 in th 
 
 e i and 
 
 
 form of j regular groups ... . 
 
 Sarcina. 
 
 i * 
 
 \A single circular layer 
 
 Clathrocystis, 
 
 / Short, isolated, in a mass or in zoogloeaa 
 
 Bacterium. 
 
 
 
 Short, jointed 
 
 Bacillus. 
 
 
 
 
 
 ^/Straight Lone itn . / S i end er 
 j filaments. p |;JJf y f 
 
 LeptothriXt 
 
 1 
 
 /Isolated, 
 
 , jointed. \Thick 
 
 Beggiatoa. 
 
 
 
 inter- 
 
 Hi 
 
 
 Cylind: 
 
 Forming 
 long 
 
 laced, 
 or in 
 bundles. 
 
 1 Spiral (Short, rigid 
 ^ filaments -( Long, flexible ... 
 
 Spirillum (Vibrio), 
 Spirochcete. 
 
 filaments. 
 
 
 
 ( Streptothrix. 
 
 \ 
 
 
 With false ramifications 
 
 
 
 
 ( Cladothrix. 
 
 
 ^In zoogloese 
 
 Myconostoc. 
 
 B. 
 
 APPENDIX TO CHAPTER III. (p. 131). 
 
 MICROCOCCUS OF PHOSPHORESCENCE. 
 
 The phosphorescence of the sea is due to the presence 
 of Noctilucce, protozoaria of the group of Flagellata, which 
 come to the surface in stormy weather. Many other 
 marine animals present the same phenomenon. The 
 phosphorescence of rotten fish is due to the presence of 
 a special micrococcus which forms large circular zoogloeje. 
 The same micrococcus also appears on putrefied meat 
 and imparts to it a phosphorescent light. 
 
APPENDIX. 305 
 
 APPENDIX TO CHAPTER III. (p. 131). 
 
 _ PLANT-DISEASES CAUSED BY BACTERIA. 
 
 The presence of parasitic bacteria lias been recently 
 pointed out as the cause of diseases in plants. In 1880, 
 Burril, of Illinois, U.S., has declared the shrivelling of 
 pears to be due to a bacterium which attacks fruit-trees, 
 and of which he succeeded in making an artificial culture. 
 In 1882, the jaundice of hyacinth bulbs was ascribed by 
 Wakker. of Amsterdam, to the development of a bacterium 
 between the layers, which may finally destroy the plant. 
 In August, 1885, Luiz de Andrade Corvo presented a 
 paper to the Academy of Sciences, in which he asserted 
 that the vine-disease ascribed to Phylloxera vastatrix is 
 really due to a bacillus, or rather, according to his de- 
 scription, to a bacterium, which is always found in the 
 tubercles of the radicles and in the tissues of the vine 
 which are affected by this disease, termed by him tuber- 
 culosis. They are also found in the body of the insect, 
 which thus becomes simply the agent of contagion. 
 
 Neither Wakker in 1882, nor Burril in 1880, was the 
 first to point out the presence of microbes in the diseased 
 tissues of plants. As early as the year 1869, Bechamp 
 noticed the presence of microzyma, that is, bacteria, in the 
 affected parts of plants (Gomptes rendus de I'Academie des 
 j vol. Ixviii. p. 466). 
 
 21 
 
S08 APPENDIX. 
 
 D. 
 
 APPENDIX TO CHAPTER IV. (p. 143). 
 
 PTOMAINE OF THE MIC KOBE OF FOWL CHOLERA. 
 
 Duclaux cites the following fact in his book, Ferments 
 et Maladies: "If a fowl is inoculated with a few drops 
 from a culture of fowl cholera, the bird sickens and dies ; 
 but if the liquid has been filtered before using it, through 
 plaster or porous china, the disease produced is not fowl 
 cholera. The bird rolls himself up and falls into a passing 
 sleep, from which he is roused by the slightest noise. 
 
 "After a few hours, his recovery is complete. Thus 
 there are two kinds of symptoms in fowl cholera, of which 
 the most apparent is due to a species of narcotic (ptomaine) 
 secreted by the microbe, but capable of independent action, 
 and not in general ending fatally." 
 
 E. 
 
 APPENDIX TO CHAPTER V. (p. 171). 
 
 CESSPOOLS. SYSTEM OF CARRYING EVERYTHING TO THE 
 SEWERS. 
 
 This system, so long advocated in Paris by Durand- 
 Claye, implies that the water should pour into the recep- 
 tacles, so as constantly to flush the drain-pipes. A minimum 
 of ten litres per diem to each inhabitant is necessary for 
 this purpose. 
 
 The household water and rain-water likewise pass 
 
APPENDIX. 307 
 
 into evacuation pipes of the sewer by sypecial sphons, and 
 help to flush them. This system has been applied to the 
 Hotel de Ville, to the new Guards' barracks, to a certain 
 number of primary schools, and to many private houses. 
 The municipal administration proposes to apply this 
 system to most of the schools, hospitals, and barracks, of 
 which the sanitary condition is at present far from satis- 
 factory. They hope eventually to extend the same system 
 to all private houses, so as to do away with the cesspools 
 a reform already effected in many foreign cities, and 
 notably in Germany. 
 
 F. 
 APPENDIX TO CHAPTER V. (p. 172), 
 
 THE SEWEES OF PARIS AND THE PLAIN OF GENNEVILLIERS. 
 
 The water issuing from the main sewer of the city is 
 partly turned into the Seine, partly into the plain of 
 Gennevilliers, and used, by a system of irrigation, for fer- 
 tilizing the soil. There was some fear lest the vegetable 
 mould might be saturated with fertilizing matter, but the 
 presence of a special microbe was ascertained, which re- 
 duces organic matter to its inorganic constituents, and 
 thus adapts them to be absorbed by plants. Schlcesing 
 and Muntz, who have studied this microbe, term it the 
 nitrifying microbe. The same system, of sewer-irriga- 
 tion will shortly be applied to another place in the neigh- 
 bourhood of Paris, Acheres, near the forest of Saint- 
 Germain. 
 
308 APPENDIX. 
 
 G. 
 APPENDIX TO CHAPTER Y. (p. 172). 
 
 USEFUL MICROBES. 
 
 We have said that numerous bacteria exist in the diges- 
 t've canal of a man in good henlth. Recent researches by 
 Duclaux, Richet, and Bourquelot tend to show that these 
 microbes are not only innoxious, but that they play an 
 active part in gastric digestion, and especially in the 
 transmutation of albumins into peptones. Since they are, 
 in fact, living ferments, the transmutation is retarded, if 
 these microbes are eliminated. It is therefore probable 
 that they manufacture pepsin. 
 
 Pasteur's experiments also tend to show that microbes 
 aid the germination of plants. If the microbes contained 
 in vegetable mould are withdrawn from it, without taking 
 away any other constituent, germination is retarded, and 
 effected with difficulty. 
 
 H. 
 
 APPENDIX TO CHAPTER V. (p. 241.) 
 
 PTOMAINES OF FISH. 
 
 Salt and smoked fish often produce in those who eat 
 them violent poisoning, which may even end in death. 
 Aurep, of Kharkov, has recently studied these causes, 
 and ascribes them to a ptomaine secreted by a microbe, 
 or perhaps evolved from the fish itself during life, under 
 the morbid influence of this microbe. 
 
INDEX. 
 
 A brine, 282 
 
 Abrus precatorina, 231 
 
 A earns, 51 
 
 Acescence in wine, 99 
 
 Achorion keratophagus, 63 
 
 Schcenlenii, 52, 277 
 
 Acidity of wines, 99 
 
 Acinetae, 3 
 
 Actinospora chartarum, 46 
 
 Action by presence, 71 
 
 Aerobies, 117, 118 
 
 Aeroscope, 160 
 
 Agaricus comestibilis, 10, 12 
 
 melleus, 41 
 
 Agnail, 236 
 Alkaloids, 238-241 
 Alopecia, 60 
 
 areata, 131 
 
 Amertume, 98 
 
 Ammoniacal fermentation, 107 
 Amoebae, 3 
 Anaerobies, 117, 118 
 AnguilUdv, 97 
 Antheridium, 30 
 Anthracnosis, 38 
 Anthrax, 132-142 
 Antiseptic dressing, 242-215 
 Antiseptics, 253-257 
 Appert's process, 251 
 Apyrexia, 185 
 
 Ascarides, 248 
 Ascococcus, 91, 93, 304 
 Ascomycetes, 13, 20 
 Ascophora mucedo, 46 
 Aspergillus, 33, 275, 278 
 
 glaucus, 26 
 
 Attenuation of pathogenic mi. 
 
 crobes, 269 
 Aubernage, 39 
 
 B 
 
 Bacillus, 92, 304 
 oanylobacter, 110 
 
 butyricus, 110 
 
 komma, 198, 203 
 
 of anthrax, 133, 134 
 
 of cholera, 197, 198 
 
 of foot sweat, 232 
 
 of gangrene, 232 
 
 of glanders, 149 
 
 of leprosy, 228 
 
 of malaria, 183 
 
 of phthisis, 225 
 
 of pneumonia, 230 
 
 subtilis, 175 
 
 Bacteridia, 93 
 
 , their vegetable nature, 
 
 Bacterium, 93, 3U1-304 
 
 ceruginosum, 130 
 
 bombycis, 152 
 
 ' cyanogenum, 129 
 
310 
 
 INDEX. 
 
 Bacterium decalvans, 131 
 
 lineola, 95 
 
 porri, 232 
 
 prodigiosum, 127 
 
 subtilis, 175 
 
 termo, 86, 87, 88 
 
 xanthinum, 129 
 
 Baregine, 120 
 Ba?ides, 12 
 BasidiomyceteSj 14 
 Bechatnp's theory, 291 
 Beggiatoa, 119, 304 
 
 alba, 119 
 
 Bitterness of wine, 103 
 Blastema, theory of, 286 
 Boil, 236 
 Boissons, 82 
 Botrytis baasiana, 50 
 Bougie Chamberland, 249 
 Butyric fermentation, 105, 109 
 
 Carbuncle, 236 
 Caries, dental, 177-179 
 
 , dry, 63 
 
 , of cereals, 17 
 Carpozyma apiculata, 75 
 Catallacta, 3 
 Catalytis, 71 
 Cattle plague, 146 
 Cellulose, 9, 10 
 Chcetonium chartarurn,, 46 
 Chalk, microbes of, 124 
 Chamberland filter, 240-248 
 Chlorococcus, 160 
 Cblorophyl, 10 
 Cholera, fowl, 142 
 
 , mode of propagation, 207 
 
 , microbe of, 195-206 
 
 Cilia, vibrating, 88 
 Cladothrix, 92 
 
 dichotoma, 93 
 
 Classification of microbes, 91, 301 
 
 of fungi, 13 
 
 Clathrocystis, 304 
 Claviceps purpurea, 20, 21 
 Coprins, 44 
 
 Cordiceps, 47, 49 
 
 Corpuscles, vibratile, 151 
 
 Cossus, 47 
 
 Cow-pox, 211, 214 
 
 Croup, microbe of, 215-222 
 
 Culture flanks, 162, 264 
 
 Culture of microbes, 163, 258- 
 
 268 
 Cyanophycese, 119 
 
 Dematium gigantemn, 45 
 
 Desmobacterium, 3u3 
 
 Diastase, 80 
 
 Diatomacece, 3 
 
 Diblastic theory, 168 
 
 Diphtheria, microbe of, 220 
 
 Diplococcus, 302 
 
 Disease, white, 33 
 
 Diseases, action of microbes in, 
 
 237-241, 294 
 of domestic animals, 132- 
 
 155 
 
 , human, 156-241 
 
 of plants, 305 
 
 of potato, 31 
 
 of silkworms, 50, 150-155 
 
 of the vine, 32-42 
 
 of wines, 98 -105 
 
 , produced by microbes, 7 
 
 Drawings of microbes, 2G3 
 
 E 
 
 Earth-worms, 32, 137 
 
 Ehrlich (staining method), 225, 
 
 263 
 
 Elephantiasis, 228 
 Entomophthora 1'lanchoni, 49 
 
 rimosa, 49 
 
 Entomophthorese, 49 
 Ergot of maize, 24 
 
 of rye, 20, 21 
 
 Ergotine, 23 
 Ergotism, 23 
 Erisyphe, 27 
 
INDEX. 
 
 311 
 
 Erisyphe Tuckeri, 27, 33 
 Erysipelas, microbe of, 232, 233 
 Kurotium repens, 25 
 Exanthemata, 209-215 
 
 Farcy, 149 
 Favus, 54 
 Fermentation, 66-84 
 
 , acetic, 95 
 
 , alcoholic, 75 
 
 , ammoniacal, 107 
 
 , butyric, 110 
 
 , lactic, 106 
 
 , of beer, 78 
 
 , putrefactive, 112 
 
 , vinous, 74 
 
 , viscous, 104 
 
 Ferment, of beer, 79-81 
 
 of bread, 84 
 
 of fruit, 76 
 
 of wine, 74, 75, 76 
 
 Ferments, 66-72 
 
 Fevers, eruptive, 209-215 
 
 , intermittent, 179-187 
 
 , jungle, 187 
 
 , of horses, 194 
 
 , recurrent, 187 
 
 ., typhoid, 191-194 
 
 , typhus, 191 
 
 , yellow, 189, 190 
 
 Filter, Chamberland, 240-248 
 Flacherie, 154, 155 
 Fbtgellata, 3 
 Flagellum, 88 
 Fleurs de vin, 98 
 Fowl cholera, 142 
 Fuchsin, 261 
 Fungi, 3, 9-65 
 
 Gangrene, 232 
 Germs of the air, 156-165 
 Glairine, 120 
 Glanders, 149 
 
 Glucose. 67 
 Goitre, 232 
 Gonorrhoea, 230 
 Graisse, 98 
 GregarinidfB, 3 
 Guerin's dressing, 212 
 
 Hay, infusion of, 162 
 Hepialus, 47 
 Herpes, circinnate, 56 
 Himantia cellaria, 43 
 Hymenium, 12 
 Hymenomycetes, 15 
 Hyphae, 10 
 
 Immunity, 271 
 Infusoria, 3 
 Inoculation, 269 
 
 for anthrax, 139 
 
 for cholera, 201 
 
 for pneumonia, 145 
 
 for rabies, 148 
 
 Instruments for research, 258 
 
 259 
 
 Isariapulveracea, 49 
 sphingum, 48 
 
 .Tcquirity, microbe of, 281 
 
 Kava, 83 
 Kirschwasser, 
 Koumiss. 83 
 
 Laboratory research, 258-271 
 Labyrinthulce, 3 
 
312 
 
 INDEX. 
 
 Lamellae, 12 
 
 Leprosy, microbe of, 228 
 
 Leptothrix, 92, 304 
 
 buccalis, 175 
 
 . polymorphism of, 274 
 
 Lichens, 273 
 
 Liquids, culture, 162, 268 
 
 Lister's dressing, 244 
 
 M 
 
 Malaria, 179 
 
 bacillus, 183 
 
 Malt, 80 
 
 Marsh fever, 179-187 
 
 Measurement of microbes, 263 
 
 Merulius destruens, 45 
 
 Methods of cult ire, 263 
 
 Methyl-violet, 261 
 
 Miasma, 170 
 
 , human, 191 
 
 Microbes, aerobic and anaerobic, 
 117 
 
 , chromogenic, 126-131 
 
 , classification of, 91, 304 
 
 , culture of, 263-269 
 
 , defence against, 242-257 
 
 destroyers of building ma- 
 terials, 123, 124 
 
 , in general, 1-8 
 
 of bad bread, 130 
 
 of baldness, 131 
 
 of blue milk, 129 
 
 of domestic animals, 132- 
 
 155 
 
 of human diseases, 156-241 
 
 of jequirity, 281 
 
 of saltpetre, 121 
 
 of sulphurous waters, 119, 
 
 120 
 
 of the air, 156-161 
 
 of the mouth, 172-179 
 
 of the saliva, 173 
 
 of the soil, 166 
 
 of urine, 107 
 
 of water, 165, 166 
 
 , part played by, 6, 7 
 
 , pathogenic, 282-284 
 
 polymorphism of, 272-284 
 
 Microbes, ptomaines of, 237-241, 
 
 306 
 
 , septic, 282 
 
 , strictly so called, 85-90 
 
 , their mode of action, 237- 
 
 241 
 
 , useful, 6, 305 
 
 , vegetable nature of, 85-90 
 
 Microbian theory, Pasteur's, 2U4- 
 
 299 
 Micrococcus, 91, 92, 304. 
 
 auriantiacus, 129 
 
 bombiicis, 154 
 
 candidus, 129 
 
 chlorinus, 129 
 
 cyanus, 129 
 
 diphthericus, 215 
 
 Julvus,l29 
 
 of gonorrhoea, 231 
 
 of peritonitis, 234 
 
 of pneumonia, 229 
 
 of scarlatina, 210 
 
 of srnall-pox, 211, 212 
 
 prodigiosus, 127 
 
 septicu*, 234 
 
 urew, 107, 108 
 
 viclaceus, 129 
 
 Microsporece, 58 
 Microsporidia, 152 
 Microsporon Audouini, 58 
 
 diphtericum, 220 
 
 furfur, 56, 57, 278 
 
 Microtome, 259 
 
 Microzoaria, 4 
 
 Microzyma, 4, 291, 305 
 
 Mildew, 35, 36 
 
 Mixture of different microbes, 
 
 279 
 
 Molinia, 46 
 Monera, 3 
 Montsouris, 159 
 Morts flats, 154 
 Motion of microbes, 88 
 Moulds, of dog's excrement, 27 
 
 of leather and fruit, 25, 26 
 
 of paper, 46 
 
 Mucor caninus, 27 
 
 herbarium, 46 
 
 mucedo, 28, 46 
 
INDEX. 
 
 Mucorineft, 27 
 Muscat-dine, 50 
 Mushroom, edible, 9, 11 
 Mycoderma aceti, 95 
 
 vini, 76, 96 
 
 Myconostoc, 304 
 Myxomycetes, 3 
 
 N 
 
 Noctilucce, 304 
 Nosema bombycis, 152 
 Nostoc, 90 
 
 O 
 
 GReidiospores, 16 
 (Ecidium berberidis, 17 
 
 rhamrti, 17 
 
 Oidiuin, 33 
 
 albicans, 61, 278 
 
 lactis, 278 
 
 Onychomycosis, 63 
 Oogoninm, 30 
 Oomycetes, 13, 27 
 Oospores, 27 
 
 Ophidomonas sanguinca, 128 
 Ophthalmia, purulent, 231 
 Orleans process, 96 
 Oscillaria, 9, 119, 186 
 Oscillatoria, 119 
 Osteomyletis, 236 
 
 Palmella febrilis, 182 
 
 mirifica, 127 
 
 Panistophyton ovale, 152 
 Pebrine, 150-154 
 Pelade, spurious, 24 
 
 , true, 58, 59 
 
 Pellagra, 18, 24 
 Pelletage, 19 
 Penicillium, 27, 275, 278 
 
 ferment, 275 
 
 racemosum, 47 
 
 Peronospora Barcinoncv, 202 
 
 calotheca, 29, 30 
 
 infestans, 31, 37 
 
 viticola, 35-37 
 
 Peyer's glands, 192 ; 195 
 Plilegmon, 237 
 Phoma uvicola, 38 
 Phosphorescence, 304 
 Photography of microbe?, 2 
 Phthisis, 223-228 
 Phycvrnmycecs, 90 
 Phylloxera vastatrix. 33 
 Pipjr meihysticum, 83 
 Pipette, 260 
 pityriasis capitis, 59, 60 
 
 versicolor, 56 
 
 Pneumonia, 229 
 Polymorphism of microbes, 
 
 284 
 
 Polypus, 232 
 Pows.se, 100 
 Powdered meats, 252 
 Preparations, 261 
 Protista, 3-8 
 Protococcus, 160 
 
 niralis, 1 28 
 
 Ptomaines, 239, 293 
 Puccinia coronata,, 17> 18 
 
 favi, 54 
 
 graminis, 15-17 
 
 Puerperal peritonitis, 234? 
 Pus-corpuscles, 234, 235 
 Putrefaction, 112-117 
 Pyaenia, 235 
 Pyrochoris apterus, 49 
 
 Babies, 147-149 
 Reagents, non-staining, 261 
 
 , staining, 261 
 
 Ringworm, 52-54 
 Robin's theory, 286 
 Rcesleria hypogea, 40 
 Rot, 40 
 Rust, cereal, 14 
 
 Saccharomyces albicans y 61 
 apiculatus, 76 
 
314 
 
 INDEX. 
 
 Saccharomyces conglomeratus, 75 
 
 ellipsoideus, 74 
 
 exiguus, 75 
 
 minor, 84 
 
 mycoderma, 61, 62, 76, 278 
 
 Pastorianus, 75 
 
 Reesii, 76 
 
 Saprolegnia ferax, 47, 48 
 Sarcina ventriculi, 94, 95 
 Scarlatina, 210 
 Schizomycetes, 8, 86, 91, 158 
 Schizophyta, 8, 86, 91, 158 
 Scleroti*, 20 
 
 Septic and pathogenic microbes, 
 282 
 
 vibrio, 146 
 
 Septicaemia, 234 
 
 , experimental, 146 
 
 Septine, 238 
 Sleepiness of fruit, 31 
 Small-pox, 211, 212 
 Smut of wheat, 19 
 Solid nutritive substances, 267 
 Sphacelium, 20, 21 
 Sphaceloma ampelium t 38 
 Spherobacterium, 302 
 Spirillum, 92, 304 
 
 tenue^ 114 
 
 undulatum, 174 
 
 Spirobacterium, 303 
 Spirochcete, 92, 304 
 
 buccalis, 173 
 
 Obermeieri, 188 
 
 plicatilis, 173 
 
 Splenic fever, 132-139 
 Sporangium, 29 
 Sporendonema muscce, 47 
 Spores, air charged with, 1G4 
 
 , injected into the blood, 278 
 
 Sporisorium mctidis, 18 
 Staining methods, 261 
 Staphylococcus pyogenus, 236 
 Streptothrix, 204 
 Forsteri, 232 
 
 Sulphurous waters, 119 
 Sulphur, appl cation of, 34 
 Sweat, red, 231 
 Sweating foot, 232 
 Swine fever, 143 
 Sycosis, 55 
 Symbiosis, 273 
 
 Vaccination, 211-2' 5, 209 
 
 for anthrax, 131) 
 
 Verdet, 18 
 
 Vibrio, 3, 93, 101, 117, 301, 304 
 
 rugula, 93, 118, 173, 174 
 
 sfepticus, 14H, 147 
 
 serpens, 93, 302 
 
 Vinegar, ferment of, 86, 95 
 Viscous fermentation, 105 
 
 W 
 
 Whitlow, 236 
 
 Wine, diseases of, 98-105 
 
 , ferments of, 74-78 
 
 Xerosis, 232 
 
 Yeast of beer, 78-82 
 
 Znogalactina imetrnpha, 127 
 Zoogloere, 114, 115, 12l>, 175, 
 
 304 
 Zymase, 291 
 
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