■|^.Si.;'^M 
 
 mm 
 
THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 
 OF CALIFORNIA 
 
 PRESENTED BY 
 
 PROF. CHARLES A. KOFOID AND 
 
 MRS. PRUDENCE W. KOFOID 
 
DISEASE GERMS 
 
 SUPPOSED NATURE. 
 
DISEASE GERMS; 
 
 SUPPOSED NATURE: 
 
 AN ORIGINAL INVESTIGATION, 
 
 WITH CRITICAL REMARKS, 
 
 BY 
 
 LIONEL S. BEALE, M.B., F.R.S., 
 
 Felloiu uf ihp. Royal College of Physiciatu ; Physician to King's College Hospital; and 
 
 lately Profefsor of Physiology and of General and Morbid Anatomy 
 
 in King's College, London. 
 
 COLOURED ILLUSTRATIONS. 
 
 LONDON: 
 J. CHURCHILL & SONS, NEW BURLINGTON STREET. 
 
 1870. 
 lAll Rights Reserved.] 
 
Digitized by tine Internet Arcinive 
 
 in 2008 witii funding from 
 
 IVIicrosoft Corporation 
 
 http://www.arcliive.org/details/diseasegermstheOObealrich 
 
K-(2C \\'\ 
 u.u, 
 
 PREFACE. 
 
 The views advanced in this volume have been 
 entertained by me for some years. The facts upon 
 which they are based have been referred to in several 
 papers, and especially in my Report on the Cattle 
 Plague to the Royal Commissioners, published in 
 1866. They have also been frequently mentioned in 
 my lectures during the last six or seven years. 
 
 The general conclusions at which I have arrived 
 were sketched briefly in the last course of lectures I 
 delivered at Oxford by direction of the Radcliffe 
 Trustees. 
 
 The mode of investigation adopted for -the pre- 
 paration of the specimens for examination under the 
 highest magnifying powers is the same that I have 
 employed for many years past, and has been described 
 in detail in other works. 
 
 L. S. B. 
 
 Grosvexor Street, 
 June 20th, 1870. 
 
 Pyi.353545 
 
TABLE OF CONTENTS. 
 
 Of Poisonous Matter ... ... ... ... ... ... . , I 
 
 Of a Germ .. ... ... ... ... ... ... lo 
 
 Of Bioplasm ii 
 
 OF VEGETABLE GER:\IS. 
 
 Of the Yeast Fungus ... ... ... ... ... ... ... 14 
 
 Of a Single Yeast Particle, and of its Bioplasm or Germinal 
 
 Matter, and Formed Material ... ... ... ... ... 15 
 
 Of the Production of the minute Yeast Germs ... ... ... 16 
 
 OF GERMS IN THE AIR. 
 
 Of the Detection of Vegetable Germs in the Air ... ... ... 22 
 
 The Characters of the most minute Vegetable Germs ^S 
 
 Of Germs of different kinds of Vegetable Organisms 35 
 
 Of the Origin of Vegetable Germs. Spontaneous generation ... 37 
 
 SUPPOSED INFLUENCE OF VEGETABLE GERMS 
 IN CAUSING DISEASE. 
 
 The Manner in which they might enter the Body 62 
 
 Of the Vegetable Germs actually discovered in the Fluids and 
 
 Tissues of the Higher Animals during Life ... ... ... 63 
 
 Question of derivation of Fungus Germs from higher Bioplasm of 
 
 another kind 71 
 
 Of diseases known to be due to Vegetable Organi.sms 74 
 
 Some difficulties m accepting the Vegetable Germ Theory of 
 
 Disease 7^ 
 
EXPLANATION OF THE PLATES. 
 
 Plate I, — Fig. i. Development of germs in organic fluids, showing the 
 changes from day to day. 
 
 Figs. 2 to 4. Bacteria germs under magnifying powers varying 
 from 1,800 to 5,000 diameters. 
 
 Fig 5. Most minute germs, visible under the one-fiftieth of an 
 inch object glass. 
 
 Fig. 6. Yeast cells growing, under powers of 215 and 400 
 diameters. 
 
 Fig. 7. Yeast cells with germs growing from them, magnified 
 1,300 diameters. 
 
 Fig. 8. Young growing yeast cells, imder a power of 2,800 
 diameters. 
 
 Plate II. — Fig. 9. Old spores of fungi, with very thick formed material. 
 
 Fig. 10. Germs of fungi, showing relation of bioplasm to formed 
 material. 
 
 Fig. II. Passage of bioplasm through pores in the formed 
 material, to illustrate formation of branching stems. 
 
 Fig. 12. Extremities of rapidly growing fungus stem, to illus- 
 trate rapid growth of bioplasm. 
 
 Fig. 13. Most minute bacteria x 2,800, 
 
 Fig 14. Germs of bacteria, growing and multiplying rapidly. 
 
 I'lale III. — Fig. 15. Vegetable organisms and other minute masses of 
 bioplasm from surface of villus — Cattle Plague. 
 
 Fig. 16. Vegetable organisms from a clot of blood. 
 
 Figs. 17 to 20. Living germs from contents of hermetically 
 sealed vessels. 
 
 Fig. 21. Vegetable growth in mucus. 
 
 Fig. 22. Vegetable growth-^ in dilTcrent stages of development in 
 sputum. 
 
EX PLANA TION OF THE PL A TES. 
 
 Plate IV, — Fig. 23. Bacteria from intestinal contents — Cholera. 
 
 Fig. 24. Free bacteria germs from columnar epithelium — Cholera 
 X 1,800. 
 Fig. 25. Bacteria in the contents of an obstructed capillary. 
 Fig. 26. Vegetable germs in blood of a cow which died of Cattle 
 Plague. 
 
 Fig. 27. vSporules of fungi in contents of capillary. 
 
Germinal Matter and the Contact Theory. 
 
 For a general slatement of the nature of morbid poisons and the 
 growth and changes occurring in germinal matter in disease, the reader 
 is referred to a little work by Dr. Morris, entitled " Gemiinal Matter, 
 and tlie Contact Theory : an Essay on the Morbid Poisons, their 
 nature, sources, effects, migrations, and the means of limiting their 
 noxious agency." Chitrchill and Sons. 
 
 Concerning Magnifying; Powers. 
 
 In order that some idea may be formed of the degree of magnifying 
 power of the one-Jiftielh of an inch object glass, lately made for me by 
 Messrs. Powell and Lealand, it may be stated, that if it were possible to 
 see a human hair in its entire width under this power, it would appear 
 to be nearly one foot in diameter, and an object an inch in height 
 would be made to appear 250 feet high. A child of three feet would 
 look about as high as Mont Blanc. 
 
 An Apparatits for CoLLECTiNti Particles suspended in Air. 
 
 Dr. Maddox has described a convenient arrangement for the purpose 
 of collecting solid particles suspended in the atmosphere, in the Monthly 
 Microscopical Journal for June ist, 1870. This ought to have been 
 referred to on p. 22 ; but, unfortunately, that part of my work was 
 revised l)eforc 1 received the [ournal. 
 
DISEASE GERMS: 
 
 THEIR 
 
 SUPPOSED NATURE, 
 
 |«^^|OISONOUS matter exists in different states. 
 
 T^^ There are poisonous solids, poisonous liquids, 
 
 ' ^ and poisonous gases. These kill man and the 
 
 higher animals in many different ways. Some 
 destroy the textures of the body ; others interfere with 
 the due discharge of function on the part of certain 
 tissues and organs, the proper action of which may be 
 necessary to the living state ; while others again 
 actually kill the living matter of the body ; and of 
 these there are poisons which act as soon as they 
 pass into the organism, almost instantaneously, — and 
 poisons which produce their deleterious effect very 
 slowly. There are again substances w^hich act as 
 poisons to every known kind of living matter, while 
 certain principles of vegetable origin which destroy 
 some vertebrate animals with unerring certainty may 
 be eaten freely by others, and even constitute their 
 ordinary food. 
 
 Of all the poisons which cause the death of man, 
 the most subtle and the most difficult to isolate and 
 
 B 
 
OF POISONS. 
 
 investigate are those which give rise to certain forms 
 of disease which spread from person to person. Many- 
 poisons of this class, as compared with non-Hving 
 poisonous agents, act very slowly, and when they 
 destroy life, do so, not by their immediate action 
 upon tissue or living matter, but by their indirect in- 
 fluence upon the physiological changes going on in 
 various tissues and organs. Many of these poisons 
 are indeed uncertain in their action, and are for the 
 most part fatal to a very small percentage of those 
 attacked. They not unfrequently cause serious struc- 
 tural damage in consequence of which the organism 
 becomes predisposed to certain forms of disease ; and 
 oftentimes, it may be not until some time has elapsed, 
 although the individual invaded escapes with his life, 
 some delicate organ is irreparably injured by the 
 changes produced by the action of the poisonous 
 material, and death follows after a varying interval of 
 time. 
 
 These poisons not only seriously derange the healthy 
 functions, but having entered the body they multiply- 
 many million fold. They are living, and increase as 
 living particles alone increase. They grow, they 
 feed upon the nutrient juices of the organism and 
 upon the tissues, and in some cases flourish at their 
 expense and destroy them. The poison when it 
 enters may be so infinitesimal in quantity, that it 
 can neither be measured nor weighed, nor under 
 ordinary circumstances seen ; but having gained access 
 
CO NT A GIOUS MA TTER. 
 
 to the blood and tissues, it increases to such an extent 
 that in many cases sufficient is produced in one sub- 
 ject to infect hundreds of persons, the population of a 
 town, or even a whole country. 
 
 The infecting matter has been supposed by some 
 to consist of some subtle entity, which was not 
 cognizable by the senses, or to be made evident in 
 any way. By others it has been considered to be 
 matter in a gaseous state. Great authorities have 
 defined it, with apparent precision, to be a chemical 
 body, which may exist as a volatile vapour,* in a 
 solid state, or dissolved in fluid. With a still more 
 decided appearance of precision, the contagious poi- 
 son has been pronounced to be an albinninoid matter 
 in a state of rapid chemical change, which has not 
 yet been isolated. Thus, the Cattle Plague Commis- 
 sioners expressed the opinion that the poison of 
 that highly contagious malady was probably matter 
 " of a kind which is, and always will be, undiscover- 
 able by the microscope." They remark '* that 
 
 * The view that some contagious poisons are volatile seems to have 
 been adopted because it has been found that the disease could be pro- 
 pagated through air and by the breath of the affected man or animal, 
 but such a conclusion is unjustifiable, for, as is well known, par- 
 ticles as large as starch globules can be wafted from place to place by- 
 currents of air, and these are not volatile. Moreover, multitudes of 
 insoluble particles, of determinate size, always exist, buoyed up by the 
 ordinary air on the surface of the earth. But solid particles should not 
 be called volatile unless they can be converted into vapour which, by 
 condensation, again assumes the general form and state the particles 
 first exhibited. 
 
 B 2 
 
COMPLEX ALBUMINOID POISON. 
 
 chemistry has as yet (1866) found in Cattle Plague 
 no complex albuminoid matter in a state of rapid 
 chemical change, capable of communicating its own 
 action to the albumen of the serum of the blood, and 
 of the textures of cattle." The author of these 
 sentences, unwittingly perhaps, expounds the doctrine 
 he himself believes, and desires the public should 
 adopt. Though he admits that chemistry has not 
 found the matter, he intimates that ere long success 
 may be attained. On the other hand, he has no hope 
 whatever that the microscope will ever assist in the 
 discovery of the poison. The poison is ahvays to re- 
 inaiii 7indiscoverable by this instrument ! Here is one. 
 mode of investigation authoritatively condemned with- 
 out reason and without knowledge on the part of him 
 who condemns it, and another exalted with unmis- 
 takable affection and partiality, although its short- 
 comings are admitted. At the very time these 
 sentences were written, the poisonous matter Jiad been 
 made out by the microscope, and the contagious ma- 
 terial of more than one contagious malady had been 
 actually figured in the report which is here criticised, 
 and which the writer is supposed — for he does not 
 hesitate to comment upon it— to have read and 
 studied. 
 
 Those who are acquainted with the theories now 
 entertained upon this very important and interesting 
 question, know that many of them are based upon 
 the results of microscopical enquiry. There are 
 
CO NT A GIO US D US T. 
 
 indeed no other means of investigation yet discovered 
 which afford equal prospects of success. Moreover, 
 by this method of enquiry important results have been 
 already obtained. It was therefore unfortunate that 
 microscopical investigation should have been con- 
 demned by the authority of a Royal Commission, 
 and the suggestion offered that chemistry was likely 
 to succeed in detecting particles of matter which it is 
 only possible to discern by the aid of very high mag- 
 nifying powers employed with due care. 
 
 Notwithstanding the publicity given to many mere 
 physico-chemical theories and the energetic means 
 taken to force them into popular favour, the view that 
 the poisonous matter of self-propagating (Dr. Budd) 
 diseases, really consists of some kind of living sub- 
 stance (germinal or living matter), has been steadily 
 gaining ground, although it must be admitted that 
 many of the statements which have been made in its 
 favour are of the vaguest and most unsatisfactory 
 description. Thus many persons seem to have adopted 
 the strange notion that dust is made up -of disease 
 germs. The harmless ingredients of this material 
 have been spoken of as if they were disease-propa- 
 gating particles of the most terrible kind. The 
 innocent organic fragments detached from our carpets 
 and rugs and dresses and furniture, have been treated 
 as if they were contagious. 
 
 Of those who accept the^^r;;^ theory of disease, some 
 hold that the living particles which grow and multiply 
 
DISEASE GERMS. 
 
 in various kinds of decomposing organic matter, are 
 derived not from germs floating in the air, but have 
 been built up ab initio — result in fact from sponta- 
 neous generation or heterogenesis. These think to 
 fortify their position, which indeed sorely needs even 
 an appearance of strength, by such remarks as the 
 following : — " There is not a physiologist of eminence 
 who would deny the possibility of the origin of 
 organic forms direct from the inorganic, while many are 
 convinced of the truth of the doctrine," and so on, — 
 as if this sort of statement could in any way influence 
 the judgment, or help the elucidation of the truth as 
 regards the question at issue. 
 
 On the other hand, it is not uncommon to find 
 writers in our journals aflirming with the utmost con- 
 fidence, that these so-called genus are fictions of the 
 imagination, that they have never been seen, and that 
 the air, which by some is said to teem with disease 
 germs, is entirely free from them. 
 
 Some authorities have opposed the germ theory of 
 disease by the argument, that if the supposed germs 
 really did exist, they would certainly exhibit well- 
 marked distinctive characters. But there is no ground 
 whatever for the opinion that the particles which are 
 instrumental in propagating contagious diseases, if 
 living, should exhibit specific structural peculiarities. 
 That the several kinds of contagious matter of small- 
 pox, scarlet fever, and other eminently contagious 
 maladies, arc distinct, each being imbued with its 
 
LIVING MATTER. 
 
 own Specific and peculiar power, is demonstrated by 
 observation, but that this difference in power or pro- 
 perty should be associated with any recognizable 
 difference in appearance, form, chemical composition, 
 or any physical characters, is exactly what a careful 
 examination of the facts, and a judicial weighing of the 
 evidence, would not lead us to anticipate. If, indeed, 
 these poisons really consist of living matter, analogy 
 would lead us to conclude that they would not be dis- 
 tinguishable from one another, except by the effects 
 they produce. For we cannot distinguish one form 
 of healthy living matter from another. The living 
 matter which produces nerve, or muscle, or bone, is 
 just like — at least as far as we can ascertain — that 
 which gives rise to cuticle or to cartilage.'^ Though 
 the results of the life of these several kinds of living 
 matter are so very different, the matter itself appears 
 similar in all cases ; and, examine it as we may, we 
 cannot discover any distinguishing marks. Nay, the 
 living matter of one animal is like that of another. 
 No form of animal living matter can be distinguished 
 from the living matter of a plant, or from that of any of 
 the lowest simplest forms of existence. Discarding the 
 results of observation, some writers have indeed main- 
 tained that the anatomical elements or cells of morbid 
 growths have peculiar characters of their own, and 
 can invariably be distinguished from those of healthy 
 structures ; but repeated failure of the attempts to do 
 so on the part of those who held that the distinction 
 
8 DISEASE GERMS. 
 
 existed, necessitates a modification of this view. But 
 even if characteristic differences could invariably be 
 pointed out in the anatomical units or cells, it is quite 
 certain that the living matter of the most virulent 
 cancer, or of the most inveterate contagious malady 
 could not be distinguished from that of the harmless 
 growth, or healthy tissue at any period of its ex- 
 istence. 
 
 The old doctrine, that the disease-carrying particles, 
 are germs derived from and capable of producing 
 microscopic vegetable organisms, has been recently 
 revived and extended. Since the investigations of 
 Pasteur, and the publication of the observations of 
 Salisbury and others, the vegetable or fiuigits germ 
 theory of disease has received a large accession of 
 advocates. According to this view, there are different 
 species or varieties of fungi corresponding to the 
 several contagious maladies with which we are 
 familiar. 
 
 We must not, however, conclude that if disease 
 germs really do consist of living bioplasm or germinal 
 matter, they must necessarily be of a vegetable nature 
 and have sprung from vegetable organisms, or have 
 originated spontaneously, for it is obviously possible 
 that, though living, their nature may be very different, 
 and that they may have been derived from a different 
 source. While I freely admit that the facts of the case 
 are conclusive as regards the living state of the active 
 matter of contagious diseases, I am quite unable to 
 
VEGETABLE GERM THEORY, 
 
 subscribe to the arguments advanced in favour of the 
 Vegetable Germ TJieory of disease. 
 
 But it is time we should pass on to consider what 
 is the nature of the supposed germs to which con- 
 tagious maladies are now attributed. If the opinion 
 is very generally entertained that the materies morbi, 
 the virus or coiitagium of contagious diseases consists 
 of germs which are introduced into the organism, the 
 exact nature of the germs in question, at any rate is 
 the subject of much discussion, and, indeed, the nature 
 of germs generally, as well as the question of origin of 
 these bodies, and the manner in which they act has 
 given rise to many different theories. And surely it 
 is a point not only profoundly interesting, but of vast 
 practical importance, and worth any effort, to deter- 
 mine, whether the germs upon which the communi- 
 cability of contagious diseases alone depends, are 
 certain species of low simple organisms of definite 
 character, produced in the outside world indepen- 
 dently of man, or are bodies which have originated 
 in man himself, and are to be regarded as degraded 
 forms of living matter, derived by direct descent from 
 some form of human living germinal matter or 
 bioplasm. If the first supposition — and this is the 
 favourite doctrine at this present time — should turn 
 out to be correct, there appears much less hope of 
 extirpating the diseases the germs produce, than if 
 the last-mentioned theory, or some modification of 
 this, should turn out to be true. 
 
lo OF A GERM, 
 
 Of a Germ. — The term genu can only be correctly 
 applied to a particle that is alive; but there are 
 multitudes of different kinds of germs. It used to 
 be supposed that the germ grew in a manner peculiar 
 to itself ; but we now know that however varied may 
 be the substances resulting from the changes taking 
 place in germinal matter, every kind of this living 
 material, at every stage of existence, ^r^^£/j" essentially 
 in the same manner, though at a very different rate. 
 The living particle which sprouts from a cell of the 
 adult plant or organism, and is then detached, may 
 be called a germ, as well as the living particle formed 
 in the ovum, or the living matter in the ovary from 
 which the new being is evolved. Any living particle 
 growing or capable of growth, may be termed a 
 ^^ germr '^Y^xy germ comes from living or germinal 
 matter, and from this only. A particle of living 
 matter, less than the — ^ th of an inch in dia- 
 
 I 00000 
 
 meter, is a living germ. Figs, i to 8, plate I. It 
 may take up lifeless matter, and convert this into 
 living matter like itself, and thus grozu. It may 
 then divide and sub-divide, and thus a mass of 
 considerable size may result. The original germ 
 may give rise to successive generations of new 
 particles, " germs " having similar powers or pro- 
 perties ; or from it may emanate higher types of 
 organization, having special formative powers, from 
 which new germs may or may not proceed. So that 
 a germ is hut a partiele of living matter, ivJiieJi Jias 
 
BIOPLASM. 1 1 
 
 been detached from already existing living matter, and 
 this living n tatter came from matter of some sort 
 which lived before it. 
 
 Of Bioplasm. — Hitherto, I have employed the 
 simple term germinal or living matter, to denote the 
 active matter which is alone instrumental in the for- 
 mation of all living beings and their tissues and 
 c^-gans ; but this term is lengthy, and, in some respects 
 awkward, and inconvenient. It cannot be used alone 
 when speaking of a single particle, nor can it be 
 employed adjectively. The word Protoplasm has 
 been much used for some years past, but the vague- 
 ness attached to it is fatal to its employment here. A 
 word is wanted to denote living, forming, growing, 
 self-producing germinal matter, as distinguished from 
 matter in every other state or condition whatever. 
 Now protoplasm has been applied, both in this 
 country and in Germany, to lifeless matter as well as 
 to living matter, to formed matter and tissue as well 
 as to the formative matter. And quite recently. 
 Prof Huxley and others have added to the confusion 
 by giving it a still wider signification — so very wide, 
 indeed, that almost anything that ever formed part of 
 an organism may be called protoplasm. Roast 
 mutton, white of ^g^, and a number of other things 
 living and dead, having structure, as well as structure- 
 less, are said to consist of protoplasm ; so that the 
 word may include almost anything, and is not applied 
 to matter in any particular state. It becomes, in fact, 
 
12 BIOPLASM. 
 
 useless. The term I propose to apply to the living or 
 germinal self-propagating matter of living beings, and 
 to restrict to this, is Bioplasm (l3to<;, life ; TrXacrfia, 
 plasma). Now that the word Biology has come into 
 common use, it seems desirable to employ the same 
 root in speaking of the matter which it is the main 
 purpose of biology to investigate. Bioplasm involves 
 no theory as regards the nature or the origin of the 
 matter. It simply distinguishes it as living. A living 
 white blood-corpuscle is a mass of bioplasm, or it 
 might be termed a bioplast. A very minute living 
 particle is a bioplast, and we may speak of living 
 matter as bioplasmic substance. A cell of epithelium 
 consists of bioplasm or bioplasmic matter, surrounded 
 by formed non-living matter, which was however once 
 in the bioplasmic state. In the same way an oval 
 yeast particle consists of the bioplasm with an enve- 
 lope of formed material, which has resulted from 
 changes occurring when particles upon the surface 
 of the bioplasm died. The bioplasm of the micro- 
 scopic fungus or other organism may give off diver- 
 ticula which may become free independent bioplasts. 
 Each minute bioplast may grow, and in the same 
 way give rise to a number of other bioplasts. 
 
 The mode of growth of the bioplasm, and the 
 manner in which it undergoes conv'ersion into forjned 
 material, will be understood if Figs. 9 to 12, plate II, 
 p. 20, be attentively examined. In Fig. 12, the bio- 
 plasm is growing very rapidly at the extremity of each 
 
BIOPLASM. 13 
 
 of the branches of microscopic fungus figured. Here 
 it has imbibed much of the carmine employed to stain 
 it, and thus render it distinct, and is coloured with the 
 greatest intensity. The formed material in this 
 situation is thinner than elsewhere, sufficient time not 
 having yet elapsed for it to become of the ordinary 
 thickness which it exhibits in that part of the branch 
 which is fully formed. The formed material is thick- 
 ened by deposition, layer within layer, in the manner 
 shown in Fig. 9 a, and as will be again referred to 
 further on. (See page 16.) 
 
 In order to form a general notion of the nature and 
 properties of living germs which consist partly or en- 
 tirely of Bioplasm, it will be necessary to consider care- 
 fully what takes place when a very simple organismx 
 grows. I propose, therefore, in the first place to discuss 
 the question of the formation of the yeast fungus or 
 yeast cell. The organism is so common that any one 
 can easily obtain it and study for himself the pheno- 
 mena which will be referred to. This will form a good 
 introduction to the consideration of the vegetable gcnn 
 theory of disease, which will clear the way and prepare 
 us for the full consideration of the highly interesting 
 but complex question of the nature and origin of the 
 contagium, or virus, of contagious or self-propagating 
 diseases. 
 
14 VEGETABLE GERMS. 
 
 OF VEGETABLE GERMS. 
 
 Of the Yeast Fungus. — If on a warm summer's day 
 or in a warm room a piece of germinating yeast about 
 the size of a pin's head be placed upon a glass slide, 
 covered with very thin glass and gently pressed, so as 
 to form a very thin layer, and then examined under a 
 microscope having a magnifying power of about 300 
 diameters or upwards, numerous little transparent, 
 colourless, oval bodies Avill be seen all over the field. 
 The bioplasm of these may be coloured by carmine 
 (Figs. 6, 7, 8, plate I.). They vary in size much more 
 than is generally represented in published drawings 
 of them, and many are joined together. If the stratum 
 of yeast be made very thin, as may easily be effected 
 by firm even pressure upon the thin glass, numerous 
 very minute bodies will be observed amongst the well 
 marked yeast corpuscles. The yeast consists of the 
 distinct oval bodies, the minute particles (detached 
 germs), and a fluid in which both are suspended. 
 
 If now the apparently smooth oval bodies be sub- 
 jected to examination under a still higher power 
 (1,000 diameters, or upwards), many of them will be 
 found to exhibit little eminences, which project from 
 various parts of the surface. Sometimes only one 
 such eminence, and sometimes as many as a dozen, 
 may be counted in connection with one oval yeast 
 cell (Fig. 7, plate I.). These are undetached germs ; 
 
A YEAST GERM. 
 
 15 
 
 and if the yeast cells be kept under the field of the 
 microscope for some hours at the proper tempera- 
 ture, and then examined again, the little projections 
 already adverted to will be found to have increased 
 in size, and some will have detached themselves from 
 the parent yeast cells. Thus the minute bodies (germs) 
 suspended in the fluid portion of the yeast have 
 arisen from yeast cells which existed before them. 
 The little eminences or projections are, in fact, buds 
 or germs formed by the yeast cell, and when de- 
 tached, constitute new yeast plants, and thenceforth 
 become independent organisms. Each germ or bud 
 was for some time connected with the parent cell, 
 from v/hich it originated. The very material of 
 which it consists was continuous with that of the 
 parent. The matter of which it was formed, in fact, 
 formed a part of the parent mass, as is well seen in 
 Figs. 7 and 8, plate I., page 16. Once detached, how- 
 ever, each little germ becomes an independent living 
 thing, and never joins again the particle from which 
 it emanated. Many of these germs detached are 
 represented in Figs. 7 and 8. The free germ may 
 multiply while it remains in the germ stage of exist- 
 ence, or it may grow into the likeness of its parent if 
 supplied with the .proper nutrient material and placed 
 under conditions favourable for its advance to a higher 
 stage of its development. 
 
 Of a single yeast pa7'ticle and of its Bioplasm and 
 formed Material. — If a single yeast cell be carefully 
 
1 6 OF YEAST GERMS. 
 
 examined it will be found to be composed of two 
 different kinds of matter, the one smooth, transparent 
 and external, forming a membrane closed at all points, 
 and commonly known as the cell wall (formed ma- 
 terial), the other soft, diffluent, also transparent, 
 but apparently composed of semi-fluid matter {ger- 
 minal matter or bioplasm). If the yeast cell be firmly 
 pressed between glass plates it will burst, and the 
 contents will be squeezed out as soon as the rupture 
 of the protecting envelope has been effected. This 
 envelope or cell wall varies in thickness in different 
 cells, being firm and thick in the oldest, and so thin 
 as to be demonstrated with difficulty in the youngest 
 cells. The envelope itself is formed not by the de- 
 position of matter from the surrounding medium upon 
 the surface of the cell, but from the soft diffluent 
 bioplasmic matter within. This envelope is thickened 
 by the formation of new formed material from the 
 bioplasm which is deposited layer within layer upon 
 the inside of the already formed capsule, cell wall, 
 or envelope (Fig. 9 a, plate II.). The germinal or living 
 matter or bioplasm, can be coloured with an ammo- 
 niacal solution of carmine, while the formed material 
 remains perfectly colourless. This fact is shown in 
 the figures which have been coloured so as to resemble 
 the specimens from which they have been carefully 
 copied (see Plate I., figs. 6,J,%; plate II., figs. 9 to 12). 
 Of tJie production of the minute Yeast Germs. — Now, 
 how are the little buds or offsets or gemmules of the 
 
?ig. 1. 
 
 GERMS.— FUNGI. 
 
 'M. \ 
 
 Fjg. 6. 
 
 
 PLATE I. 
 
 :9o>;v <^r?j 
 
 
 
 Development of germs in organic fluid, o, 12 
 
 hours after tlieir first appearance. 6, one day. 
 
 c two days, d, four days, e, five, and/, six 
 
 days, X 2i5, p. 10. 
 
 Teast cells, growing during forty-eiglithours. 
 a X il5. 6 X 400. pp. 14. -.6. 
 
 Fig. 2. 
 
 n.icteria germs from tlie 
 mouzia. X 1800. p. 34. 
 
 Fig. 3. 
 
 i © e 
 
 The same. X 3000. p. 34. 
 
 Fig. 4. 
 
 ^1^ 
 
 aa 
 
 The same. X 5000. v. 31 
 
 Fig-. 5. 
 
 The most min\ite germs of fungi 
 visible under the -jq. The 
 smallest is much less than the 
 Too'ono of 3,n inch in diameter. 
 p. 31. 
 
 Growing yeast cells, showing diverticula frora each mass 
 
 of the bioplasm. These are from time to time detached 
 
 each germ when set free may grow and produce others 
 
 X 1300. 1867. pp 14, 19. 
 
 Fig. S. 
 
 Growing yeast cells and most minute germs, wdl stained 
 
 with carmine and magnified by the -^q = 2800 diameters. 
 
 p. 14. Nov., 1869 
 
 of an inch x v;]5 linear. 
 
 ,, X 1800. 
 
 „ X i^SOO. 
 
 „ X 5000. 
 
 [To face page 16. 
 
B I 'DS, GEMMULES. 
 
 yeast plant formed ? Do they result from the growth 
 of the external envelope with which they are certainly 
 for a time connected, or is the soft diffluent material 
 within concerned in their production ? This question 
 can be answered conclusively from direct observation. 
 Never do we find a bud which does not contain sonic 
 of the soft diffluent germinal matter ; never one com- 
 posed of the matter of the envelope only (Figs. 7, 8, 
 Plate I.). In the formation of these buds a very small 
 portion of the soft material protrudes through minute 
 pores in the envelope, perhaps pushing a very thin 
 layer of this latter before it, through which it imbibes 
 nutrient matter from around. It soon increases in 
 size forming a little nodule or button which remains 
 for a time connected with the parent mass by a very 
 narrow pedicle (Fig. 8, Plate I.). This pedicle con- 
 sists externally of matter like that of which the 
 envelope or cell-wall is composed, but in its centre 
 may be traced a very thin line of bioplasm, by which 
 the bioplasm or germinal matter of the bud remains 
 for a time connected with the parental bioplasm. 
 This line cannot be discerned in every instance, but 
 from the numerous observations I have made I do not 
 believe it is ever absent at this period of growth. I 
 have seen the diverticulum of germinal matter in so 
 many cases already projecting from the general mass, 
 that I feel sure the above description is correct. When 
 multiplication is going on with great rapidity, the mode 
 of formation of the buds may in fact be demonstrated 
 
 C 
 
1 8 YEAST PAR TICLES 
 
 with the greatest certainty, as represented in Fig. 8, 
 plate I. 
 
 The material of which the cell wall consists (formed 
 material) passes gradually into the germinal matter, 
 when the plant is germinating quickly, and the abrupt 
 line, which marks the internal boundary of the cap- 
 sule in many specimens, is absent. These points are 
 given in the drawings, Figs. 7 and 8, the latter, in which 
 the formed material is made too thick, taken from a 
 specimen magnified by the fiftieth. 
 
 Where growth is active, the yeast cells are em- 
 bedded in a soft material continuous with the external 
 surface of the envelope, as represented around the 
 yeast particles in the central part of Fig. 8. This 
 probably consists partly of matter which is drawn 
 towards the surface of the cells by the currents of 
 fluid which are setting towards the germinal matter 
 within, and partly of imperfectly hardened formed 
 material. Thus there always appears to be a space 
 between the outer part of one and the outer parts 
 of neighbouring cells. 
 
 The very soft material, which consists of imperfectly 
 formed matter, that by gradual condensation as- 
 sumes all the characters of the cellulose wall of the 
 yeast particle, corresponds to the mucus which lies 
 between the particles of bioplasm concerned in the for- 
 mation of that substance, and bears the same relation 
 to the envelope of the yeast cell as the viscid mucus 
 does to the wall of an epithelial cell embedded in it. 
 
STAINED IViril CARMINE. 
 
 When yeast has been successfully stained with car- 
 mine fluid it forms a beautiful object for investigation, 
 and with the aid of very high powers many points of 
 the greatest interest may be discovered. The cells 
 represented in Fig. 7, plate I., were growing very 
 rapidly. Protrusions or outgrowths are seen pro- 
 jecting from every part of the bioplasm, and in some 
 instances the latter appears to have been preserved 
 while it was in the very act of moving. I have speci- 
 mens of the bioplasm of mucus, of epithelium and of 
 cartilage, which illustrate the same point. In every 
 case the continuity of the bioplasm of the little out- 
 growth with the general mass within the cellulose 
 wall can be well seen. In Fig. 8 are represented some 
 of the smallest and simplest of the yeast particles 
 under a magnifying power of 2,800 diameters, the Jq- 
 of an inch object glass. Both these drawings illustrate 
 the mode of formation of germs in this very simple 
 organism, and it will be shown in another part of this 
 work that the bioplasm of man and the higher animals 
 gives off diverticula in much the same manner ; and 
 that these when detached become free bioplasts. 
 
 The diffluent germinal matter within the yeast cell 
 is the material upon which alone all growth and action 
 depend. Were it not for the bioplasm or germinal 
 matter the cell would be lifeless and passive — inca- 
 pable of " exciting fermentation " or any change what- 
 ever. Every particle of the bioplasm is living, and 
 may, under favourable circumstances, undergo develop- 
 
 C 2 
 
20 BUDS OR GEMMULES. 
 
 ment into complete yeast cells, so that by the artificial 
 division of one, thousands may result. And if the soft 
 bioplasmic matter which can be expressed from the 
 yeast cell be placed under favourable conditions, every 
 particle of it may germinate. This matter alone 
 furnishes the germs, it alone grows and appropriates 
 the nutrient material, in short it alone manifests 
 phenomena peculiar to living things. 
 
 The little buds or gemmules above referred to, de- 
 tached from the parent mass, and capable of indepen- 
 dent existence, are, many of them, much less than the 
 tott'o oo-th of an inch in diameter. But each is living 
 and will grow, under favourable circumstances, into a 
 body like the parent cell, giving origin in its turn to 
 countless descendants. These very minute particles 
 divide and subdivide independently, producing still 
 more minute particles, capable of growth and division 
 like themselves, not one of which, however, may be 
 developed into an ordinary yeast cell like those 
 represented in Fig. 6, plate I. This mode of multi- 
 plication may go on for a long period, perhaps for an 
 indefinite time, if certain conditions persist. But if any 
 one of these excessively minute particles falls into a 
 medium containing suitable pabulum, it will appro- 
 priate it, and soon pass on to a higher stage of de- 
 velopment. In this case branches may be formed, as 
 represented in Fig. ii, plate II., and more advanced 
 in Fig. 12. See also Plate III., fig. 22. From them 
 may proceed stems which grow upwards into the air. 
 
PLATE II. 
 
 Fig. 9. 
 
 GERMS.— i'UNGI. 
 Fig. 10. 
 
 Old spores of fungi, in wliicli the 
 formed material has become very 
 thick. At a the bioplasm is passing 
 through pores. Its further growth 
 is given in Fig. 10. x 180O. pp. 12, 16. 
 
 Germs of fungi, show 
 ing the relation of the 
 bioplasm to the formed 
 material and the pro- 
 duction of the latter 
 from the former. 
 X 1600. p. ■2-2. 
 
 Passage of bioplasm through 
 pores in formed material, show^- 
 ing the manner in ■which the 
 branching stems of fungi are 
 formed, x 1*.0. p. 20. 
 
 The extremities of a branching stem of a rapidly-growing fungus from jam. At ^he apex, where 
 
 the cellulose wall is only just forming, it is so thin as to be hardly demonstrable. The germinal 
 
 matter in this situation is abundant, and it is here principally that growth takes place, x ^lo 
 
 a, a spore which has just commenced to sprout, X 500. 1869. pp.12 21. 
 
 Fi^. 13. 
 
 Fig. 14. 
 
 Most minute bacteria growing and multiplying 
 Shown in outline. X 2800. pp. 21. 34. 
 
 
 Germo of bact<=na, growing and jnuiLijjiymg 
 rapidly X 1800. 1866. pp. 21.34. 
 
 To5o of an inch 
 
 To o oo > > <> 
 
 . X 215 linear. 
 X 130G. 
 
 [To face page 20. 
 
GERMS IN THE AIR. 
 
 and bear upon their summits heads in which spores 
 are formed, these last being so well protected from the 
 influence of destructive agents, that the germinal 
 matter within can retain its vitality for a great length 
 of time. Fig. lo, plate II. 
 
 GERM.S IN THE AIR. 
 
 The spores just referred to are so light as to be 
 easily supported in the atmosphere, and they may be 
 carried a long distance by currents of air. The in- 
 finitesimal germs before adverted to are of course 
 transported still more readily. Some of these are 
 represented in Fig. i, plate L, and some of the most 
 minute that can be discovered with the highest powers 
 of the microscope, in Figs, i to 5, and in Figs. 13 and 
 14, plate II, Bodies weighing lOO times as much as 
 these can be supported in air. There is, therefore, no 
 wonder that germs so very small and light are 
 almost constantly present in our atmosphere. Myriads 
 no doubt perish for one that falls in a spot w^iere it 
 meets with suitable food and other advantageous con- 
 ditions. It is not to be wondered at that such minute 
 germs as these should exist almost everywhere, float- 
 ing in the atmosphere, deposited upon everything, and 
 ready to undergo development wherever the conditions 
 may be favourable. And the vitality of the bioplasm 
 of lowly organisms of the kind under consideration 
 is so great, that protected as it is by its external en- 
 
OF DETECTING GERMS 
 
 velope of formed material, it is able to resist effectually 
 and for a long time the disturbing influence of adverse 
 external conditions. Should these lead to the death 
 of a great part of the living matter or bioplasm, it 
 must be remembered that by this very change, the 
 thickness of the external envelope is increased, and 
 thus the speck of living matter which remains, be- 
 comes still more effectually protected than it was at 
 first (see Figs. 9 and 10, plate II.). 
 
 Protected in this way, multitudes of such germs 
 escape destruction. Provided only a speck of living 
 matter remains, and resists the influence of adverse con- 
 ditions, it will increase undei favourable circumstances. 
 Particles will make their way through pores in the 
 envelope, and coming into contact with the pabulum 
 outside will soon increase and develope minute germs 
 or branching stems as represented in Figs, ii and 12. 
 
 Of the Detection of Vegetable Germs in the Air. 
 — Vegetable germs were detected in the air more 
 then twenty years ago by a number of observers, and 
 by many different plans of procedure. One method 
 was to cause air to be drawn through a glass vessel, 
 the outside of which was cooled by ice. Upon collect- 
 ing the water which condensed upon the interior in a 
 vessel placed beneath for its reception, and examining 
 under the microscope the slight sediment which sub- 
 sided, the germs were discovered. Another plan was 
 to cause air to be projected against glass plates, the 
 surface of which had been wetted with weak e'U'cerinc. 
 
m THE AIR. 
 
 23 
 
 water, or some other substance, to which the particles 
 would adhere ; or merely to hang up such plates in 
 the air for a time. Some observers employed paper 
 moistened with the same fluids. Pasteur investigated 
 the matter very carefully, and showed that the number 
 of germs existing in the air varied much in different 
 places and at different heights. He also found that 
 the air which had been undisturbed for some time in 
 cellars was almost destitute of germs. Mr. Crookes 
 followed a plan which had been previously adopted by 
 Schroeder, and separated germs from the air by filter- 
 ing it through pure cotton wool. He also collected the 
 germs in tubes, and upon glass slides moistened with 
 glycerine (Cattle Plague Report, 1866). It would be 
 generally concluded that many of the germs suspended 
 in air and capable of being wafted long distances by 
 currents, would subside if the air became perfectly 
 still, just as the dust in our rooms falls upon the floor 
 or is deposited upon shelves and other projections. 
 Dr. Tyndall has, however, considered it necessary 
 to demonstrate the fact that tiny particles of dust 
 really do fall down to the ground if the air in which 
 they are suspended be quiescent. By throwing a ray 
 of very bright light upon air contained in a closed 
 chamber of glass 3 ft. by 2 ft. 6 inches, and 5 ft. 
 10 inches high, tapering to a truncated cone at the 
 top, he was able to prove not only that particles of 
 dust which float in the air for a time after it has been 
 disturbed gradually subside, but that these were 
 
24 IMPOTENCE OF AIR. 
 
 deposited upon the sides of the chamber as well as 
 upon the floor. '* The chamber was examined almost 
 daily ; a perceptible diminution of the floating matter 
 being noticed on each occasion. At the end of a week 
 the chamber was optically empty, exhibiting no trace 
 of matter competent to scatter the light" This ex- 
 periment is calculated to convince any one who doubts 
 the fact that particles of lifeless matter, even when 
 very minute, really do tend to fall through air, until 
 they reach some resting place which prevents them 
 from falling still lower, and the great discovery is 
 announced that ponderable bodies are ponderable. 
 But the demonstration determines nothing whatever 
 with regard to living particles, not even their pre- 
 sence. 
 
 Dr. Tyndall also makes a prediction concerning the 
 discovery of the cause of the impotence of certain 
 air as a " generator of life," as if aii^, which is lifeless, 
 could under any circumstances generate that matter 
 which lives. Has any one been educated into a belief 
 in the life-generating properties of the air .'' 
 
 The nature of the materials which make up the 
 dust of our air is a subject which has often engaged 
 the attention of microscopists, who have long been 
 familiar with the fact that multitudes of organic par- 
 ticles derived from various sources are floating in the 
 more or less disturbed air of our rooms. Many of 
 these fall into our microscopic specimens w^hile they 
 are being mounted, and in spite of all our care, and 
 
EXTRANEOUS MATTERS. 25 
 
 the use of glass shades and other means, we often 
 preserve portions of hair, feathers, scales of the 
 wings of insects, and a number of other foreign bodies 
 which we would gladly exclude from our prepara- 
 tions. The characters of these organic particles 
 are but too well known to us, and probably hun- 
 dreds of microscopists have many times examined 
 the dust which commonly collects upon shelves and 
 little projections from the walls of our rooms, for the 
 very purpose of demonstrating the many different 
 kinds of organic fragments of which it is in great part 
 composed. Memoirs have been written upon the 
 extra^ieous matters which fall into urine, sputum, and 
 other secretions which it is the business of the physi- 
 cian to examine. These extraneous particles which 
 have been deposited from the dust suspended in the 
 air of the rooms have given rise to great confusion, 
 and some of them have been mistaken for bodies 
 derived from the organism of man. No wonder, there- 
 fore, that much attention should have been given to the 
 examination of dust, and in order to prevent mistakes 
 figures of some of the most important constituents of 
 dust have been given.* Particles of hair and wool of 
 various kinds, filaments of cotton and silk, portions of 
 insects, especially the scales of the common clothes- 
 moth, starch granules, pollen grains, fragments of 
 wood, and animal and vegetable germs, are among 
 
 * See for example " How to Work with the Microscope," 4th edition, 
 p. 195, Plate XLIV. 
 
2 6 DUST AND HAZE. 
 
 the many organic constituents of dust which are 
 famihar to microscopical observers. Pouchct found 
 in the dust of the air [Comptes Rendtis, March 2ist, 
 1859), ** the detritus of the mineral crust of the earth, 
 animal and vegetable particles, and the minutely 
 divided debris of the various articles employed in our 
 wants." Mr. Samuelson, many years before 1863, 
 obtained living germs from dust taken from the 
 window panes, and from other common-place localities, 
 and gave numerous figures of the different forms he 
 discovered (''On the Source of Living Organisms," 
 Quarterly Journal of Science, Vol. I., p. 598). 
 Many other observers have also examined dust of 
 various kinds with great care, and have described 
 the organic particles existing in it in great numbers. 
 Yet in spite of the numerous observations which 
 have been made and published upon this subject, we 
 find Dr. Tyndall teaching the public in a lecture on 
 " Dust and Haze,'' given at the Royal Institution on 
 Feb. 1 8th, 1870, and afterwards published in several 
 newspapers, that he had only just discovered that the 
 dust of our air contained organic particles. His re- 
 marks were afterwards more widely diffused in several 
 journals under the title " Dust and Disease," no con- 
 nection whatever having been shown by the lecturer 
 to obtain between disease and dust or between either 
 and germs. Dust may certainly be perfectly harmless."^ 
 
 * Witness tlie cavalcade of picturesque stalwart women crossing llydc 
 I'ark every evening on their way from the dust-heaps at I'adclington, to 
 
DUST AND DISEASE. 
 
 27 
 
 On the other hand, is it impossible that disease germs 
 may exist free from dust ? 
 
 Dr. Tyndall had thought " with the rest of the 
 world, that the dust of our air was in great part inor- 
 ganic and non-combustible." But from the " rest of the 
 world" must be excluded the majority of those who 
 have used a microscope or are acquainted with the use 
 of this instrument. Ought a lecturer endeavour to 
 excite the astonishment of his audience by trying to 
 convince them that until lately he was quite un- 
 acquainted with some things very generally known, and 
 when his hearers have become sufficiently interested 
 in this want of information on his part, relate as some 
 new discovery what he has happily to introduce to 
 their notice } Dr. Tyndall has discovered that the 
 little particles of cotton and hair and wool and 
 feathers and other organic substances which exist in 
 the air, can be destroyed by a red heat and converted 
 into smoke, which would not be the case had they 
 consisted of inorganic matter as he supposed before he 
 tried the experiment he proceeds to repeat.* 
 
 their homes at Westminster. Whatever may be said against them, they 
 are evidently persons in rude health and more affected by the passive 
 organic and inorganic constituents of the dust than by its active disease- 
 producing germs. . 
 
 * Dr. Tyndall, after the publication of his lecture, announced in 
 the "Times," that Dr. Percy had discovered that the dust upon the 
 walls of the British Museum contained 50 per edit, of inorganic matter 
 — this, in support of Dr. Tyndall's belief, that the dust of our air was in 
 great part inorganic and non-combustible. But Dr. Tyndall says nothing 
 about the nature of the remaining 50 per cent, of this dust. 
 
28 COTTON WOOL AND ALPINE AIR. 
 
 But more than this, Dr. Tyndall professes to be 
 able to bring " the air of the highest Alps into the 
 chamber of the invalid." This grand result he pro- 
 poses to achieve by causing the dusty air to traverse 
 cotton wool, by which operation the dust which had 
 been demonstrated together with the germs supposed 
 to be mixed with it are filtered off. Even Dr. Tyndall 
 will scarcely be inclined to deny, after a little quiet 
 reflection, that the promise to bring Alpine air into 
 the London sick rooms, may appear to unromantic 
 people who actually attend upon invalids more like 
 the result of emotional excitement than a conclusion 
 deduced from any exact methods of observation or 
 experiment. 
 
 By the physical method of examination, particles of 
 wool and cotton and hair, scales and other particles 
 from insects, and starch and soot, and all the other con- 
 stituents of dust, alive and dead, organic and inorganic, 
 are illuminated so as to form one confused ray, which 
 can be seen at a great distance ; but, it need scarcely 
 be said, the brightest light the physicist can cause to 
 beat upon them fails to reveal the nature of the 
 several dust particles, or enable anyone to distinguish 
 the living particles from the lifeless debris ; or the 
 virulent disease germs, should there be any, from the 
 harmless dust. Now, instead of burning all the organic 
 matter together, the living and the lifeless with the 
 non-living, including that which exhibits form and 
 structure, and that which is formless and structureless, 
 
GERMS AND DUST. 
 
 29 
 
 and demonstrating the smoke resulting from the 
 destruction of all, any one with the aid of a microscope 
 in less time, with less trouble, -without complicated 
 apparatus, might have quickly demonstrated, and with 
 the greatest precision identified the various kinds of 
 organic particles present in that particular specimen of 
 dust, and he could have shown the particles them- 
 selves instead of the smoke which resulted from their 
 combustion and destruction. In short, the method of 
 burning dust proves only what can be proved quite as 
 positively by much simpler means, and proves abso- 
 lutely nothing regarding the existence of disease or 
 other germs in the air — a subject which has been suc- 
 cessfully studied during the last ten years or more by 
 other methods of inquiry. It is difficult to imagine 
 anything further removed from fact than the state- 
 ment that the dust of our air consists of disease 
 germs. No one would dare to make such an assertion 
 in plain words. It would be nonsense. And yet 
 remarks have been made which have undoubtedly 
 led the public to infer that such a conclusion was 
 implied, or that it was desired that such an Inference 
 should be drawn. It is, however, still more astonish- 
 ing that writers in some of our leading journals should 
 be so misled as to give, without comment, an inter- 
 pretation of an author's views which amounts to 
 absurdity. Thus the "Academy" (April 9th, 1870, 
 p. 185), in referring to Dr. Tyndall's lecture on Dust 
 and Disease remarks, " The floating dust-like matter 
 
30 
 
 DR. T YNDA LVS S TA TEMENTS 
 
 revealed in the air by a sunbeam is organic, probably 
 germs of animal and vegetable life.'' 
 
 In a subsequent letter to the "Times " (April 2ist), 
 Dr. Tyndall says that the organic matter of London 
 air is not all ''germinal matter!'' The lecturer has 
 spoken of germs, animalcules and germinal matter, but 
 he does not explain whether these terms are used by 
 him for the same thing or for different things. . He 
 speaks of the " morass of wordy discussion and contra- 
 dictory argument," in which he says, without identifying 
 the offender, " the germ theory of disease and the 
 question of spontaneous generation are entangled," 
 and with surpassing simplicity he assures the editor of 
 the " Times " that he is " unpledged to more than a 
 clear statement of the germ theory," and refers to 
 the exactness of physics and chemistry, and to the 
 methods by which he proposes to detach " from the 
 domain of vagueness and uncertainty each successive 
 frag-ment of demonstrated truth ! " 
 
 In common fairness. Dr. Tyndall should have studied 
 the matter a little before he gave his first lecture, 
 instead of in his last characteristically excusing him- 
 self on the ground of " tenderness for the public,"* for 
 not alludinef to the researches of others, and for with- 
 
 'i3 
 
 * The considerate tenderness which, as a rule, is reserved exclusively 
 for the public, is, it must be a Imittcd, on one occasion extended to- 
 wards an individual. Dr. Tyn(iall did indeed admit that he could 
 not read without "sympathetic emotion" the papers of an observer, 
 whom, however, a stern sense of justice compels him to regard as "a 
 ninn of stroni^ imagination'' — as one "who may occasionally take a 
 
AND CONCLUSIONS. 
 
 3T 
 
 holding from the press statements concerning these 
 which he had " twice or thrice written down." Had he 
 done so, there would be less reason to condemn or to 
 laugh at the following paragraph with which he con- 
 cludes his last letter to the Editor of the " Times," 
 and retires for the present from the consideration of 
 dust, disease, and germs. '' For a long time to come 
 I shall be unable to devote any attention to this sub- 
 ject, and this has caused me to write at what I fear 
 you will consider inexcusaJ3le length : were the ques- 
 tion of less practical interest to humanity, I should 
 not have troubled you either with this or with any 
 former communication."* 
 
 It would indeed be difficult to point out a series 
 of conclusions less justified by the experiments. 
 
 flight beyond his facts!" but he tenderly observed, "as long as the 
 heat (dynamic heat of heart by which alone the solid inertia of the free- 
 born Briton is to be overcome) is employed to warm up the truth with- 
 out singeing it overmuch ; as long as this enthusiasm can overmatch its 
 mistakes by unequivocal examples of success, so long am I disposed to 
 give it a fair field to work in." — "Times," February 19th, 1870. Such 
 comments are very curious, but they are not in good taste, and are 
 altogether uncalled for and out of place. Dr. Tyndall had no right to 
 speak in the way he has spoken of such a man as William Budd, of 
 Bristol. 
 
 * Dr. Bastian has expressed his opinion of Dr. Tyndall's still more re- 
 cent observations upon the influence of germs and animalcules upon disease 
 as follows : — " The question is, however, one of so complicated a nature, 
 that little save amazement will be excited in the minds of those conver- 
 sant with all the difficulties of the problem, that Professor Tyndall 
 should place so much reliance upon indirect evidence towards its solu- 
 tion, and should step forward on the strength of this, with the view of 
 establishing a doubtful theory of disease, to which he, by his own con- 
 fession, has so recently become a convert."—- " Times," April 13th, 1870. 
 
32 
 
 DR. TYNBALVS METHOD DEFECTIVE. 
 
 It is difficult to see in what way Dr. Tyndall's experi- 
 ments illustrate or affect any sort of germ theory. 
 They could all have been made without a single 
 reference to germs of any kind or to a germ theory 
 or to disease. On the other hand, these last sub- 
 jects might have been rendered more intelligible to 
 the unlearned if their attention had not been diverted 
 by the brilliant illuminations and combustions. 
 
 The mctJiod is defective. The Professor first points 
 out that he supposed that dust consisted of inorganic 
 particles. He discovers to his surprise that it con- 
 tained organic matters. Next he seems to wish that 
 his audience should regard these organic matters as 
 germs or animalcules, or at any rate look upon some 
 of the particles of dust as composed of " germinal 
 matter." But Dr. Tyndall did not demonstrate what 
 the organic particles in air were, nor did he prove that 
 dust contained anything whatever that would give 
 rise to disease. The particles might have consisted 
 entirely of harmless germs, or of disease germs or of 
 animalcules, or there might have been a few of these 
 bodies present, or there might not have been a vestige 
 of any of them, and Dr. Tyndall would not have dis- 
 covered the difference by the method of investigation 
 he employed, of the advantages of which he speaks so 
 confidently. By his discoveries, surmises, assertions, 
 and predictions published in the " Times " and other 
 journals, people have been led to suppose that dust 
 consists of "-crms, and that air teems with animalcules 
 
rOPl U.AR TEA CUING. 
 
 and disease-producing particles, which is not really 
 the case. 
 
 There is now a strong feeling in favour of scientific 
 teaching. And branches of science, particularly those 
 capable of illustration by experiment, are deservedly 
 popular. But if the feeling in favour of scientific educa- 
 tion is to be lasting, and not a mere fashion, and if it is 
 desirable that the public should have any respect for 
 science, her exponents must not put out what they 
 have to teach in a sensational form. Undoubtedly the 
 public may with good reason find fault with many of 
 us for being slow and dreary, dry and uninteresting, and 
 for presenting our lessons in a hard, unpalatable, not 
 easily digestible form. But in endeavouring to escape 
 these faults, it is very undesirable that any tendency 
 towards the gushing and hysterical or rhapsodical, 
 should be permitted. Our object it must be distinctly 
 understood is to teach, and not to excite or surprise 
 or amuse. There are theatres, and in great number, 
 established for the very purpose of affording amuse- 
 ment where we may enjoy excitement and wonder and 
 surprise to our heart's content, but the scientific work- 
 room is built for instruction and for real earnest work. 
 
 TJie CJiaracters of the most inhuitc Vegetable Germs. 
 — The very minute vegetable organisms which may 
 be obtained from the air, and which are developed in 
 infusions of animal and vegetable matter, are for the 
 most part of an oblong oval form, frequently exhibit- 
 ing a constriction which corresponds to the point of 
 
 D 
 
34 
 
 MOST MINUTE GERMS. 
 
 division (see Fig. 20, plate III.). Some are, however, 
 much more elongated than others. Compare Figs. 
 15, 16, 21, plate III., with Figs, i, 2, 3, 4, plate I. ; 
 but whether these represent different species, or are 
 merely variations due to the circumstances under 
 which they have been developed, is not known. Some- 
 times a very elongated form is found amongst nu- 
 merous short ones, Plate II., fig. 13. 
 
 The general appearance of minute germs of fungi 
 multiplying rapidly in fluid favourable to their de- 
 velopment, is represented in Plate I., fig. i, under a 
 power magnifying only 200 diameters. The most 
 minute germs (bacteria) visible under the higher powers 
 are seen in Figs. 2, 3, and 4, which are magnified 
 respectively 1,800, 3,000, and 5,000 diameters linear. 
 In Fig. 5 the appearance of very minute particles of 
 bioplasm, which have been well stained with carmine 
 and examined under the -Jp, which magnifies 2,800 
 diameters, is represented. 
 
 Some notion of the manner in which the most 
 minute germs multiply, may be formed if Figs. 13 and 
 14, plate II., opp. p. 20, be carefully examined. 
 Whether there is any actual firm membrane around 
 the minute particles of bioplasm represented in Pig. 
 14 is very doubtful. It is more probable that each 
 little particle of bioplasm is embedded in a soft and 
 semi-fluid formed material which has been produced 
 by it. This, under certain circumstances, may be- 
 come condensed, and thus an envelope or protecting 
 
AVA'DS OF GERMS. 3^ 
 
 covering may be formed. The particles in Fig. 13 
 are only represented in outline. 
 
 The minute germs developed in infusions in closed 
 vessels are represented in Figs. 17 to 20, plate III. 
 These are referred to in page 49. But the somewhat 
 definite characters manifested by these particles last 
 mentioned, are not exhibited by the most minute 
 germs discovered by the aid of the highest powers. 
 These, like the most minute particles of other kinds 
 of bioplasm, always appear as little specks of a 
 rounded form. There is no possibility of identifying 
 the different kinds of bioplasmic matter under the 
 microscope. The most minute living particles of a 
 vegetable organism exactly resemble those of an 
 animalcule or those which may become developed into 
 beings still higher in the scale ; and in another part 
 of this work it will be shown that these cannot be dis- 
 tinguished from particles of bioplasm derived from the 
 living mucus, or p?ts, or white blood-cor^pusclts of man 
 himself Every kind of bioplasm at this stage of its 
 being exhibits, as far as has yet been ascertained, pre- 
 cisely the same characters. 
 
 Of Germs of different kinds of Vegetable Organisms. — 
 Of microscopic fungi and algai there are many dif- 
 ferent kinds, which grow and multiply under very 
 different external conditions, and live upon different 
 kinds of food. Thus there are germs of numerous 
 different species diffused through the air and wafted 
 long distances at different seasons. Some flourish at 
 
 D 2 
 
36 SPECIES OF GERMS. 
 
 a temperature which would be fatal to others ; some 
 live upon vegetable, some upon animal, matters. 
 Some require solid substance upon and into which 
 they may grow, while others seem to obtain from the 
 atmosphere alone all the materials required for their 
 growth and development. Some enjoy light, while 
 others vegetate freely in darkness. Many of these 
 vegetable germs are almost constantly diffused every- 
 where in the atmosphere, ready to increase a million- 
 fold in a few hours whenever circumstances should be 
 favourable. But all increase and grow in the same 
 manner ; all consist of the growing, living, active, 
 moving bioplasm, or germinal matter, and a certain 
 proportion of the passive, lifeless formed material 
 around it, which has been already referred to. 
 
 It is supposed that germs of different species of 
 vegetable organisms give rise to the phenomena in 
 the system invaded, which are characteristic of the 
 several contagious diseases, and by which they are 
 recognized and distinguished from one another. In 
 the germ stage, however, there are no characters 
 which would enable us to determine the source of 
 the germ ; and whatever differences may exist in the 
 fully developed state, at an early period of existence 
 the embryonic living particles are alike. 
 
 It is not my purpose to direct attention to the 
 various species of microscopic fungi which are known, 
 or to discuss the vexed question concerning species 
 and variet\% or to indicate the variety of appearances 
 
ORIGIN OF GERMS. 37 
 
 which may be assumed by one species, and which 
 seem to be determined rather by varying external 
 conditions and food than to be due to inherent specific 
 powers. These questions are interesting and important 
 enough, but I must now pass on to consider several 
 points more intimately connected with the question 
 concerning the origin of vegetable germs, and their 
 supposed influence in causing disease. 
 
 Of the Origin of Vegetable Germs. — Several scientific 
 authorities of high repute have of late summed up 
 very distinctly in favour of the doctrine of the forma- 
 tion of living beings directly out of lifeless matter, 
 without the instrumentality . of pre-existing living 
 matter. On the other hand, there are men well 
 qualified to form an opinion who consider that the 
 advanced minds of the present day have been led to 
 strain facts more than was right, in order to make it 
 appear that spontaneous generation, as well as some 
 other doctrines correlated to this, ought to be ac- 
 cepted. The so-called " tendency of thought " has 
 been adduced in favour of these views ; writers of 
 advanced articles in our magazines, distinguished for 
 the brilliancy of their speculations, have written up 
 the doctrine ; and there is reason to think that no 
 inconsiderable number of readers is desirous of being 
 told, and is really anxious to believe, that living 
 things may come direct from lifeless matter, and that 
 force may build up structures and form organs with- 
 out the assistance of intelligence, or the intervention 
 
38 SrONTA.VEOUS GENERATION. 
 
 of creative power or other mysterious agency ; and 
 that matter requires but to be exposed to the influence 
 of certain conditions in order to assume the Hving 
 state. Nevertheless, every one admits that, in all the 
 instances he knows about, the living being did, with- 
 out doubt, come from a pre-existing living being. 
 But, he proceeds to argue, because a highly complex 
 creature cannot be formed direct from the dust of the 
 ground, does it therefore follow that all the simple 
 living forms modern research has brought under our 
 observation have come from pre-existing simple 
 creatures like themselves .-* Why, he asks, are we to 
 assume that a simple structureless mass of jelly vmst 
 come from a pre-existing mass of jelly .'' There must, 
 he Ui'ges further, have been, at least in the beginning, 
 a beginning of life. The living, at some time or other, 
 did spring direct from the lifeless. If, then, it is ad- 
 mitted that this has happened once, is it unreasonable, 
 he might ask, to conclude that it happened more 
 than once, nay, many times, nay, he might remark, 
 may we not feel sure that it has happened lately, and 
 is going on daily and hourly } 
 
 It is very generally admitted that ever since life 
 first appeared on our earth uninterrupted develop- 
 ment has proceeded, and it is maintained by many 
 that the evidence in favour of the view that the 
 higher forms have been derived by descent from lower 
 ones, is almost conclusive ; and, it might be said by 
 those who accept the doctrine, since " spontaneous 
 
UNINTERRUPTED DEVELOPMENT. 3^ 
 
 generation is still in operation, the lineal descendants 
 of the simple beings which are now being evolved in 
 vast numbers direct from the non-living, will, after 
 the lapse of ages, during which progressive change 
 shall never cease, become the parents of highly de- 
 veloped organisms totally distinct from any which 
 have yet existed, and of which we, with our imperfect 
 knowledge of the properties of the particles of non- 
 living matter, cannot form even the faintest concep- 
 tion. But if our knowledge was sufficient, we should 
 be able to determine now the specific characters of 
 the creatures that are to be in the ages yet to come." 
 May we not argue back with equal justice that the 
 producer is greater than the thing produced, and that, 
 therefore, we ought to go at once to the fountain 
 head for life, which on this theory would be the 
 simplest non-living matter ? Further, it has been 
 argued, " since we can trace a certain gradational re- 
 lationship between the higher and the lower forms of 
 living beings, we may consider it proved that the non- 
 living is related to the lowest, simplest living in the 
 same sort of way." The new philosophy, after affirming 
 that the higher life passes by imperceptible grada- 
 tions into the lower life, enquires, can it be possible 
 that any one with intelligence should doubt for one 
 moment that the lowest life passes gradually into the 
 non-living } And modern philosophy boasts of her 
 exactness, and professes to accept nothing that can- 
 not be proved by observation and experiment. But 
 
40 HETEROGENESIS. 
 
 her disciples occasionally forget the iron rules they 
 have laid down for others, and here, as in some other 
 instances, after asserting that as the first position is 
 proved, the second must be true, they just suggest that 
 if no\Lproved to be true, it is at any rate capable of proof, 
 or if not actually provable just at this present time, is 
 sure to be proved to demonstration before very long I 
 
 Any objection to such remarks as these, which are 
 pronounced to be in harmony with the tendency of 
 modern thought, are accounted frivolous. But, fortu- 
 nately, or unfortunately, according to the stand-point 
 taken, every one does not feel able to accept these ar- 
 guments, and in spite of being considered foolish 
 enough to attempt to oppose the whole tendency of 
 modern thought, which is undoubtedly difficult, and 
 perhaps impossible, I must, nevertheless, venture to 
 remark that the doctrine of heterogenesis has not yet 
 been proved to be true as respects one single living 
 organism, and it is unfortunately the case that some of 
 the *' facts " which have been adduced in its favour are 
 not facts at all, while of the " facts " some have been 
 misstated and many misinterpreted. 
 
 He who does not accept the doctrine of the hour 
 is, in these days, in danger of being denounced as a 
 bigot, and stigmatized as ortJiodox because his 
 rejection of the physical and sensational is held to 
 prove him to be a bigoted believer in every antiquated 
 doctrine that has ever been demolished by the bright 
 light of research in the time that has passed. He is 
 
CONTINUITY OF LIFE. 
 
 also likely to be reproached as a heretic because he re- 
 fuses to bow down to the phantom called the tendency 
 of modern thought. But unreasoning credulity is not 
 peculiar to old beliefs, neither is persecution. If the 
 bigot of former days set physics at defiance, does not 
 many a modern philosopher unquestionably attribute 
 to physics phenomena which are altogether beyond the 
 range of merely physical law } It is even doubtful if 
 the unreasoning faith of the skilled scientific does not 
 sometimes exceed the vulgar belief of the poor igno- 
 rant bigot. If the bigot is to be accused of believing 
 in spite of reason, the sceptic of modern times some- 
 times exposes himself to the charge of justifying his 
 disbelief by argument which has been proved to be 
 false, as well as by advancing as a fact what is really 
 but an assertion in a fact form. If the bigot may be 
 laughed at for his belief in the unseen and unknowable, 
 how is the modern enthusiastic believer in the omni- 
 potence of the material to escape ridicule } 
 
 Hov/ever absurd, and against all the accumulated 
 evidence of observation, it may be to believe in the 
 immediate creation of any particular species of com- 
 plex plant or animal, it is at any rate equally absurd, 
 and also quite contrary to any evidence yet obtained, 
 to maintain that living forms result from the direct 
 combination of particles of inanimate matter. And 
 whatever may be said in favour of the uninterrupted 
 continuity of life, and of the gradual alteration of liv- 
 ing forms from age to age — all that has been proved 
 
42 
 
 HE TEROGENESIS. 
 
 in connection with the growth and development of 
 every class of living beings, tells against the doctrine 
 of heterogenesis. And many who have written in its 
 favour have convicted themselves of inconsistency, 
 unless it be consistent to believe at the same time in 
 the law of continuity and succession, and in a law 
 which involves discontinuity and interruption as applied 
 to the production of living forms at this present time. 
 I will, however, admit that upon such a question as 
 heterogenesis, any one acquainted with the facts and 
 arguments on both sides, and well accustomed to the 
 marshalling of evidence in order, would, by a judicious 
 selection of his facts, soon adduce evidence which would 
 convince the unlearned of the truth of that view which 
 he chose to advocate. Just at this time many circum- 
 stances have fostered in the public mind a demand for 
 arguments in favour of the origin of living beings from 
 mere matter independent of a superintending will. 
 People have been so well educated that they do not 
 recognise the oft-repeated assertion, that living beings 
 are being continually made out of inanimate matter 
 without the aid of already existing living beings, as a 
 mere dogma, in direct support of which well authen- 
 ticated facts and conclusive experiments cannot be 
 adduced. That with some heterogenesis is accepted as 
 an article of belief is not disputed here. There is no 
 harm in this, but that there is reasonable ground for 
 the faith must be distinctly denied. And it is pro- 
 bable that the doctrine would have attracted very 
 
PUBLIC TEACHING. 
 
 43 
 
 little attention if it had not been forced into undeserved 
 notoriety in consequence of the support it seemed to 
 afford to modern matter-and-force views. 
 
 There has been far too much tendency of late to 
 decide scientific questions by a show of hands. A 
 very little tact is required to make a number of people 
 who know little about the matter look with favour 
 upon a new theory, for in their enthusiastic haste 
 to upset old creeds of which they are tired, they 
 are sure to neglect to ascertain whether the new one 
 they accept is really as reliable as the old one they 
 discard But the cry " Hurrah for spontaneous gene- 
 ration," will not advance the cause, for happily, 
 science is not like politics, in which people may take 
 sides and settle things by acclamation, and action has 
 to be determined by expediency and a number of con- 
 siderations quite apart from the mere question of truth 
 or of fact. In science, views are changed in no time, 
 and theories most popular for a while are discarded 
 the instant some new fact is revealed. Nothing 
 can however retard scientific discovery more than the 
 attempt to convert scientific deliberations into mere 
 party questions. Science is open to all the world, and 
 although excuses have been made for spreading inac- 
 curacies on the ground that it was necessary to put the 
 subject in a form to please unlearned persons — such 
 excuses are utterly inadmissible. The unlearned public 
 can understand any scientific question that is put before 
 them clearly if they choose to take the trouble to 
 
44 
 
 THE LA W OF CONTINUITY. 
 
 do SO ; and he who sacrifices accuracy to briUiancy 
 and sensationalism ofifends in two directions, for 
 he can have no respect for the inteUigence of the 
 people whom he really misleads, but is profess- 
 ing to teach, and he brings discredit upon science, 
 gaining only for himself thoughtless applause. 
 People who care very little about scientific investiga- 
 tion are encouraged to express themselves convinced 
 of the truth of this or that scientific doctrine, just as 
 vast numbers have believed in the truth of the table- 
 turning, spirit-rapping, and other fanciful manifesta- 
 tions. They appeal to evidence which they assert to 
 be convincing to their judgment, although the 
 favourite views may be opposed to known laws, 
 and be inconsistent with demonstrated facts. 
 
 That ninety-nine hundredths of the living beings on 
 this globe should be derived from living beings that 
 existed before them, while one hundredth, or one 
 thousandth, or one ten thousandth should result di- 
 rectly from non-living matter, is very improbable ; but 
 because it is affirmed that such a view is *' advanced," 
 and in harmony with the whole tendency of thought, 
 people do not stop to consider its probability or im- 
 probability. Continuity prevails as a law, but con- 
 tinuity is not to be universally applicable. Experience 
 and observation demonstrate in thousands of cases 
 that living matter is derived from living matter, and 
 yet we are asked to believe that in some instances 
 living matter comes from lifeless matter, because the 
 
SCIENTIFIC PROPHECIES. 
 
 45 
 
 active and energetic minds of the day assert this. 
 We are told authoritatively that we must believe that 
 the non-living passes by gradations into the living, 
 although the bodies supposed to establish the fact of 
 these gradations exist only in the imaginations of 
 those who make the assertion. It is unsatisfactory, if 
 not useless, on the part of any one, however great the 
 authority he wields, to declare that although sub- 
 stances in a state of transition from the non-living to 
 the living cannot yet be produced, they will be dis- 
 covered at sovie future time. Why are we to believe 
 him } Of all prophecies the prophetic assertions of the 
 scientific are the least worthy of belief, for the scientific 
 spirit is utterly incompatible with the spirit of pro- 
 phesy. No one can have so mistaken his calling in 
 this world as the scientific man who ventures to pro- 
 phesy, and yet the prophetic spirit seems to prevail 
 in scientific quarters where it would be least expected. 
 Even Professor Huxley cannot quite resist the tempta- 
 tion of foretelling what will be possible in a certain 
 time. He says that he believes it possible before 
 half a century has elapsed, that man may be able to 
 take inorganic substances, such as carbonic acid, 
 ammonia, water, and salines, " and be able to build 
 them up into protein matter," and that that protein 
 matter may " begin to live in an organic form." Of 
 course he does not consider it necessary to give any 
 reasons for such a strange opinion. It is supported by 
 authority, but where are the facts which support it .-* 
 
46 SPONTANEOUS GENERATION. 
 
 Not one of the many who have joined the ranks of 
 the heterogenists has succeeded in giving us any con- 
 ception of what, according to the doctrine he accepts, 
 really occurs when the non-living matter becomes 
 alive. No one who affirms spontaneous generation 
 has ventured even to theorize upon this. Is it that 
 the supporters of this view are at a loss to conceive 
 what takes place, or are they afraid to commit them- 
 selves to an opinion concerning the rudimentary facts 
 upon which the faith they profess to believe rests } 
 What can that doctrine be worth the fundamental 
 facts of which are not to be examined } To maintain 
 that lifeless matter spontaneously assumes the living 
 state, and not be able to give the faintest notion of 
 what occurs when the change takes place, is not 
 furthering investigation but sowing dogma. No one 
 has any right to assert that the non-living can become 
 living without the influence of the living, because at 
 this present time such a change is against experience 
 and is not conceivable. Marvellous, indeed, must be 
 the change which occurs at the moment when the 
 living imparts to the particles of the non-living its 
 wonderful powers. Anyone who has seen living matter 
 increasing, and moving, and dividing, will feel that it 
 is useless to attempt to divine the nature of the change 
 which takes place. How utterly impossible, therefore, 
 must it be to conceive what may occur upon the 
 hypothesis that the non-living becomes living without 
 the intervention of any living matter whate\'er. 
 
GERMS.— FUXGI. 
 
 PLATE III. 
 
 Fig. 16. 
 
 ^ <^ .. m 
 
 ilasses of bioplasm and vegetable organisms 
 
 (bacteria?) inactive movement from surface 
 
 of villus in cattle plague. Ttie bacteria axe 
 
 only shown in ouUine. X 2800. pp 34, 66. 
 
 Hg. 17. 
 
 From central part of a dark red clot taken 
 from aorta— cattle plague— witMn twenty -four 
 hours after death, a, largest red blood corpus- 
 cles and those of average si?e: some were stel- 
 late. 6, vegetable organisms, bacteria only 
 shown in outline, c, white blood corpuscles, 
 exhibiting active movements, X 700. pp.3i,66. 
 
 Fig. 19. 
 
 Fig. 20. 
 
 
 c^^ 
 
 Living organisms found in closed vessels into which fluid and organic matter had been previously 
 
 introduced, due care having been taken to exclude air. The contents of the flasks had been well boiled. 
 
 The large oval bodies in Fi6s 17. 16, are crystals. Fig. 17 X 1700, Fig. 18 X 1700, Fig. 19 X 1700 Fig. 20 
 
 shows one of the smallest objects in Fig. 19 x 2>00. pp. 31, 49. 
 
 Fig. 22. 
 
 '/^± 
 
 A S' -« ,9 
 
 Fig. 21. 
 
 
 
 
 ■'i^^fl,. 
 
 Vegetable growths in the mucus 
 of the gaU bladder. Cattle 
 plague. These organisms vrere 
 very numerous. Belo^v a. a 
 myeloid corpuscle, x 1800. The 
 vegetable organisrus only shown 
 in outline, p. 66. 
 
 
 \ / 
 
 ^^r^fmmn^^- 
 
 \ X2!":. 
 
 Fungi in diflferent staaes of growth in the sputum of a patient 
 
 in the last stage of phthisis. Spores or germs are seen tc be 
 
 very numerous, and the stems have grown from these . 
 
 X -215. p. 20 
 
 of an inch. 
 
 X 215 linear. 
 X 7o: 
 
 L. S. B.,lc£o. 
 
 [lo face pasC 46. 
 
EXPERIMENTS. 
 
 47 
 
 The results of many experiments have, however, 
 been brought forward in favour of the doctrine of 
 heterogenesis. Organic matter, air, and water, which 
 have been subjected to various operations supposed 
 to effectually destroy any living particles that may be 
 present, have been introduced into glass vessels which 
 have afterwards been hermetically sealed. In spite of 
 every precaution germs have made their appearance, 
 and it has been inferred therefore that these sprang 
 into existence without being in any way indebted to 
 parental organisms. 
 
 In 1864-65 I examined with Dr. Child the content.^ 
 of several hermetically sealed glass flasks, into which 
 various vegetable infusions had been introduced. In 
 order to prevent the entrance of germs from the air, 
 and to destroy any germs which might exist in a living 
 state in the matters introduced into the flasks, the 
 following precautions were adopted by Dr. Child. 
 ("Essays on Physiological Subjects," second edition, 
 page 116.) 
 
 " In these experiments I have adopted some slight 
 modifications of the apparatus used in the former ones. 
 That now employed consists of a porcelain tube, the 
 central part of which is fitted with roughly pounded 
 porcelain ; one end is connected with a gas-holder, 
 and to the other the bulb is joined, which contains the 
 substance to be experimented upon. The bulb has 
 two narrow necks or tubes, each of which is drawn out 
 before the experiment begins, so as to be easily sealed 
 
48 EXPERIMENTS IN FAVOUR OF 
 
 by the lamp ; one neck is connected with the porcelain 
 tube, as already stated, by means of an india-rubber 
 cork, and the other is bent down and inserted into a 
 vessel containing sulphuric acid. The central part of 
 the porcelain tube is heated by means of a furnace, 
 and when it has attained a vivid red heat the bulb is 
 joined on the end of the porcelain tube, which projects 
 from the furnace, being made thoroughly hot imme- 
 diately before the cork is inserted, the cork itself being 
 taken out of boiling water, and the neck of the bulb 
 being also heated with a spirit lamp b 3fore it is 
 inserted into the cork. A stream of air is now passed 
 through the apparatus by means of the gas holder, 
 and bubbles through the sulphuric acid at the other 
 end. The substance in the bulb is then boiled for ten 
 or fifteen minutes, the lamp withdrawn and the bulb 
 allowed to cool while the stream of air is still passing 
 through the porcelain tube, maintained during the 
 whole time at a vivid red heat. When the bulb is 
 quite cool the necks are sealed by means of a 
 lamp. The advantage gained by means of this 
 apparatus is that there is only one joint the perfec- 
 tion of which in any degree affects the success of the 
 experiment, and of that joint it is easy to make sure. 
 The porcelain tube also, being for a considerable part 
 of its length fitted with small fragments of porcelain, 
 all heated up to redness, easily insures that every 
 particle of air admitted to the bulb sliall be thoroughly 
 lieated." 
 
S PONT A NE US GENERA TION 
 
 49 
 
 In many instances undoubted organisms in a living 
 state were identified, but the number present varied 
 greatly in different flasks. The cause of the difference 
 was not in all instances clear. In many cases the 
 germs were so very minute, that I am quite sure they 
 would have completely escaped observation if an 
 object glass magnifying upwards of i,ooo diameters 
 linear had not been employed. These observations 
 necessarily lead us to conclude that the failure of 
 observers who have worked with quarters and object 
 glasses magnifying less than 500 diameters, is easily 
 accounted for. Even Hallier, I believe, carried on his 
 more recent observations with very low powers, and I 
 believe the observations of both Pouchet and Pasteur 
 are open to objections upon the same grounds. 
 
 Some of the organisms discovered in Dr. Child's 
 infusions are represented in Figs. 17 to 20, plate III, 
 from drawings made by myself. The large dumb- 
 bell shaped bodies represented in Figs. 17, 18, are 
 not organisms, but crystals. They could be readily 
 distinguished from the living forms by their high 
 refractive power, larger size, and absence of any 
 movement. 
 
 It was supposed that boiling was fatal to all living 
 things ; then it was proved by experiment that 
 some living things, under certain circumstances, did 
 live in spite of being subjected to a temperature even 
 above that of boiling water. But was it therefore 
 necessary to assert authoritatively that no living 
 
 E 
 
50 GRIG IX OF GERMS. 
 
 organisms could live at a temperature a certain 
 number of degrees above that of boiling water, and 
 that in cases in which any living forms are found in 
 fluids in closed vessels that have been exposed to that 
 temperature, they are formed de novo ? What is there 
 to prevent us from coming to the conclusion supported 
 by so many positive general facts in nature which 
 are well known, that the living forms discovered did 
 spring from living matter which resisted the high tem- 
 perature to which they had been exposed ? 
 
 Moreover, in many of the experiments it does not 
 appear that every part of the apparatus had been 
 subjected to the high temperature. If the smallest 
 portion were left above the bath in which the closed 
 vessel was immersed, a few living germs might have 
 escaped the destructive action, and from these might 
 have been developed those which were subsequently 
 detected and supposed to have arisen in a new way. 
 
 Dr. Charlton Bastian exposed fluids to a tempera- 
 ture varying from 148 deg. C. to 152 deg. C. (298"4 to 
 305 "6 Fahrenheit) for four hours, and yet in the course 
 of a few weeks living organisms were developed 
 (" Times," April 13th, 1870). But even this striking 
 fact proves nothing concerning the actual origin of the 
 living forms, and it is more in accordance with the 
 results of observation and experiment, to conclude 
 that living forms might live though exposed under 
 certain conditions to a temperature even of 350" Fah- 
 renheit, than it would be to infer tliat tlic lixine 
 
IXFLl'EXCE OF HEAT A VD COLD. 
 
 51 
 
 bodies present originated spontaneously in a fluid 
 after it had been exposed to this high temperature. 
 In every instance in which hving forms have been 
 attributed to spontaneous generation, the possibihty 
 of their origin from germs cannot be denied or dis- 
 proved. 
 
 We have yet very much to learn concerning the 
 influence both of high and low temperatures upon 
 the minute particles of bioplasm constituting the 
 germs of the lowest forms of life. And there is no 
 doubt that the effect of the same degree of tempera- 
 ture would be different at different phases of the life 
 of each species of fungus or low organism, and at 
 different periods of the year. The effect would also 
 vary according as the organisms were exposed to 
 sudden great alterations of temperature, or submitted 
 to intense cold or heat by slow and gradual changes ; 
 and even in man and the higher animals it is remark- 
 able what great degrees of heat and cold can be borne 
 if only the change be gradual. Some of the lower 
 forms of life are habitually exposed to a temperature 
 of 32, and would probably bear a very much lower 
 temperature without being destroyed. These crea- 
 tures, it must be remembered, are not merely exposed 
 externally to this temperature like many vertebrata 
 which have the power of developing heat within them- 
 selves, and whose temperature does not therefore vary 
 with that of the surrounding medium, but they suffer 
 every change which affects the medium in which they 
 
 E 2 
 
52 
 
 FREEZING BIOPLASM, 
 
 are placed, for their means of evolving internal heat 
 are so slight and imperfect, that these may be left out 
 of consideration altogether. Their bioplasm or living 
 matter is adapted to live and grow at very low tem- 
 peratures. Some organisms which do not grow and 
 flourish at a temperature much below 50° are never- 
 theless capable of bearing a low temperature, and 
 may even live for a length of time imprisoned in solid 
 ice. Whether the bioplasm of their organism is 
 actually frozen is very doubtful. It is more likely 
 that the bioplasm resists for a long time the process 
 of congelation, and it seems to me probable that the 
 motion which there is reason to think continues durinof 
 life, prevents the living matter from freezing. Death 
 most likely occurs before congelation takes place, but 
 when once the living matter has actually become 
 ice, its life is for ever destroyed, and it is inca- 
 pable of being revivified or revitalized. It can never 
 live or move again. 
 
 With regard to the power possessed by certain living 
 organismsof resisting the destructive influence of a high 
 temperature, it must be remarked that of certain of 
 the forms discovered in the closed vessels (see p. 47), 
 little is yet known. Many have been passed over by 
 highly distinguished observers, and it is even probable 
 that some have altogether escaped notice up to this 
 very time. Of the very minute organisms in question, 
 some may be able to resist the degree of heat to 
 which they are exposed in the course of the experi- 
 
IMPOR TA NCE OF HIGH PO IVERS. 5 3 
 
 ment without being killed — nay, there may be several 
 forms of organisms extremely minute which are at 
 present undiscovered, but which among other charac- 
 teristics possess the remarkable property of resisting 
 the destructive influence of a temperature of 300° or 
 350°. From these many might afterwards grow. 
 
 In many instances in which the absence of living 
 germs would have been inferred, minute organisms, 
 invisible by the aid of the magnifying powers usually 
 employed, have been discovered, and in considerable 
 number. And in some cases in which it has been 
 .stated that living organisms were not present, there is 
 reason to think many might have been detected, had 
 greater care in the examination been exercised, and 
 higher magnifying powers employed. But though 
 this be admitted, the fact does not in the slightest 
 degree strengthen the case for the heterogenists. 
 They have to prove that living forms appear under 
 conditions which not only absolutely preclude the 
 possibility of the entrance of living germs from with- 
 out, but which ensure the death of every living form 
 that may have been present in the substances used 
 for experiment. The position is indeed a difficult 
 one, for the more investigation advances, and the more 
 we learn concerning the minute living germs which 
 exist in such wonderful profusion, the more do we 
 hesitate to place perfect confidence in the means 
 employed for the destruction of those that were 
 present before the experiment commenced, and for 
 
54 
 
 SPONTA NE US GENERA TIOJV 
 
 excluding the entrance of living germs into the closed 
 vessels in which the actual new generation of living 
 organisms has been held to occur. Bearing in mind 
 that living particles far more minute than could have 
 been seen by the magnifying powers employed by 
 Pasteur, Pouchet, and others, undoubtedly have been 
 detected in the closed vessels, as in the observ^ations 
 of Dr. Child, for example, in which I had the ad- 
 vantage of assisting, and that germs are not invariably 
 destroyed by boiling, — I would ask, is it not more 
 reasonable to conclude that the living forms discovered 
 were derived from pre-existing germs which obtained 
 access to the fluids in consequence of the arrangements 
 made to exclude them not being quite perfect, than that 
 they had been formed anew from lifeless matter in the 
 image of those very forms which have been unques- 
 tionably developed from predecessors like themselves } 
 If the view of their formation direct from the non- 
 living be accepted, how are we to account for their 
 exact resemblance in form and actions to beings 
 familiar to us, whose parentage is known ; and for 
 the fact that further growth and multiplication pro- 
 ceed precisely as those operations occur in germs 
 derived from parental organisms .'' 
 
 But it has been suggested that although perfect living 
 forms may not be developed spontaneously, perhaps 
 a form from which these may soon be evolved, results 
 in this manner. To argue from facts revealed in the 
 course of observations made with magnifying powers 
 
FROM NON-LIVING TO LIVING. 
 
 55 
 
 so moderate as a quarter or even an eighth (two to four 
 hundred diameters) that eggs are produced spontane- 
 ously is surely, in the present state of knowledge, 
 very hazardous, if not altogether unjustifiable. Of 
 the supposed lifeless particles, by the aggregation of 
 which the eggs are said to be formed, little can be 
 learnt from observations with powers below a twelfth, 
 because higher objectives would have resolved these 
 supposed lifeless atoms into something very different, 
 and perhaps have proved, that so far from being non- 
 living particles, they were really living organisms 
 which had been living for some time, and were at the 
 time of observation at any rate far enough from the 
 inorganic. Moreover, those who have advanced this 
 theory, and those who have given in their adhesion to 
 it, have not intimated how we may ascertain wJien 
 the aggregation of lifeless particles assumes the 
 living condition ; and they have left us completely in 
 the dark as to ivJiat occurs when the marvellous change 
 in question takes place. What a wonderful disturb- 
 ance must occur at the instant of animation ! What a 
 violent dislocation of elements which were combined as 
 compounds, and what le-arrangement must take place 
 when the inanimate collection of molecules starts 
 into vitality ! What sort of force effects the change, 
 and whence arises the destructive force and the con- 
 structive power ? Not a word of explanation on all 
 this, and yet are we expected to accept as a fact 
 proved, the formation of spontaneous eggs ! 
 
56 
 
 SPONTANEOUS EGGS. 
 
 But the lifeless " proliferous disk," from which the 
 living eggs are supposed to emanate so curiously, 
 when carefully examined, is at once resolved into 
 countless millions of separate living particles, every 
 one of which lives and grows, and must be regarded 
 as a distinct germ. Every one of these millions may 
 give origin to successors, each little bioplast being a 
 distinct being with all the attributes of an independent 
 living organism, and containing within itself all the 
 marvellous self-propagating powers of a living germ. 
 I feel sure that anyone who patiently studies the 
 simplest forms of life under the highest powers of the 
 microscope, will utterly reject the so-called observa- 
 tions which are adduced in support of the formation 
 of " spontaneous eggs " by the aggregation and 
 coalescence of lifeless particles. In the ten thousandth 
 part of such a proliferous mass are living germs 
 enough to produce by simple division in the course of 
 a few hours countless multitudes of living forms. 
 
 Living particles, far more minute than the life- 
 constructing, non-living particles, have been seen and 
 studied, and they have been observed to increase and 
 multiply. But what is the nature of the mysterious 
 operation of vivifaction which takes place at the 
 rhoment of the conversion of the lifeless into living 
 matter ? Is the passage from the inanimate to the 
 living condition sudden and abrupt, or gradual } Ac- 
 cording to Owen, this process is going on daily and 
 Jiourly, so that there ought to be abundant opportuni- 
 
0)VE.V'S VIEIVS. 
 
 57 
 
 ties for studying it carefully. This authority does not 
 tell us what he means by the daily and hourly conver- 
 sion of physical and chemical into vital modes of force, 
 but surely such an investigator as Owen will not deem 
 it right to leave this bare assertion without any fur- 
 ther explanation. Every one interested in this won- 
 derful problem naturally desires that he should give us 
 some idea of the view he has formed in his own mind 
 regarding what takes place at the moment when 
 the mode of the force ceases to be physical and 
 becomes vital — when the passive atoms become 
 active organisms — when the inanimate leaves the 
 state of lifeless rest and assumes that of living acti- 
 vity — when the matter acquires converting powers 
 which it never possessed before — when, after having 
 collected together by aggregation, the now living 
 matter begins a new existence, and, instead of aggre- 
 gating, its particles move away from one another — 
 separate, never to join again. Any statements affirm- 
 ing that living particles have been seen to coalesce and 
 join, under a power of less than five hundred diameters, 
 are not to be relied on. A mistake is very easily 
 made, and before an observation advanced in favour 
 of such a statement can be accepted as true, it must 
 receive confirmation ; not only on account of the 
 errors possibly made by the observer himself, but be- 
 cause the conclusion is opposed to many broad facts 
 which may be unquestionably relied upon, and par- 
 ticularly the fact of the formation of these same 
 
58 
 
 OMNE VJVUM EX OVO. 
 
 organisms by division and subdivision, which has 
 been observed and confirmed in many cases by 
 hundreds of competent observers. Nothing is gained 
 by the statement being repeated over and over again 
 that hfeless particles of matter come together and 
 form a Hving thing, save that by mere iteration 
 people who have concerned themselves little with the 
 subject may be persuaded to assent to the view advo- 
 cated, and, without examination, prc^laim it to be 
 true. But knowledge cannot be advanced by declara- 
 tions and affirmations, or by the consent of numbers. 
 
 On the other hand, many microscopists have actu- 
 ally seen the living particles detach themselves from 
 a pre-existing living mass, and have abundant evi- 
 dence to prove that this process takes place among 
 creatures occupying various positions in the scale of 
 living beings as well as in many different forms of 
 germinal matter from the highest organisms. In some 
 of the lower creatures the process may be watched from 
 hour to hour, as it gradually progresses towards solu- 
 tion of continuity, and the formation of two beings 
 out of one is completed. I have myself frequently 
 witnessed the sub-division of living particles from the 
 organisms of the higher as well as from those of the 
 low^er forms of life, so minute and of such tenuity, 
 that they could only be seen with difficulty when mag- 
 nified 5,000 diameters ; and there is much reason to 
 think that even if the magnifying power could be 
 increased to 50,000 diameters, there would still be 
 
DIRECT LIFE-FORMATION. 
 
 59 
 
 seen only more minute living particles growing and 
 dividing and giving rise to particles like themselves. 
 Are we to believe, then, on the mere dictum of autho- 
 rity, that living germs are formed in two ways upon 
 two distinct principles ? i. By being detached from 
 parent living matter ; and 2. By the direct combina- 
 tion of lifeless particles without the intervention of 
 any pre-existing living matter at all ? 
 
 It must be freely conceded that many facts are sus- 
 ceptible of more than one interpretation, and may be 
 regarded as being of different import by different 
 minds. Nay, in some instances, the very same facts 
 have been appealed to, and not in any way unfairly, 
 in support of opposite and conflicting doctrines. With 
 reference to the question of spontaneous generation, I 
 must, however, venture to remark, that to my mind 
 the case of those who at this time hold to the doc- 
 trine of the direct origin of living beings from non- 
 living matter appears so hopelessly opposed to facts, 
 that I should as soon think of believing in the direct 
 formation from lifeless matter of an oak, a butterfly, 
 a mouse, nay, man himself, as in that of an amoeba or 
 a bacterium. 
 
 After so many failures to force people to believe 
 that the phenomena peculiar to living beings are to 
 be explained by physics alone, it was natural to 
 expect that the language employed by those who 
 still entertain such doctrines would have become 
 more guarded, if not more exact. But, on the con- 
 
6o PHYSICAL LIFE. 
 
 trary, the more conclusively it is proved that the 
 physical facts yet discovered are incompetent to ex- 
 plain vital phenomena, the more do we find vague 
 but most positive assertion used, as if this were as 
 convincing as the results of observation and experi- 
 ment. The more desperate the case becomes the 
 more violently do its advocates affirm that their cause 
 is good ; the more strongly do they assert they are 
 in the right. And yet those who are determined to 
 support the physical theory of life need not care if 
 facts and arguments are against them, for, in order 
 to prove their case to the satisfaction of many per- 
 sons they have but to exclaim triumphantly, " In 
 the years yet to come new facts shall be discovered 
 which will demonstrate conclusively the truth of the 
 physical theory of life ! " 
 
 Since cosmic vapour has- produced worlds, shall not 
 air generate life ? Was not the announcement made 
 at the Royal Institution some years ago that the sun 
 formed the heart and built the brain, and that cattle, 
 and verdure, and lilies, were his workmanship ? Why, 
 then, shall not the air divide with the sun these mar- 
 vellous powers } May we not be indebted to the sun 
 for the formation of complex organs like the heart and 
 brain, and may not the air generate that much simpler 
 moving jelly-like matter of which the simpler beings 
 are composed '^. 
 
 In conclusion, the following suggestions shall be 
 offered as an unworthy contribution towards esta- 
 
SPECULATION. 
 
 blishing an hypothesis which may illumine the path 
 of the physicist until he arrives at the demonstra- 
 tion of the physical origin of life. Since it is well 
 known that the infinitely minute particles of cosmic 
 vapour, of which by mere aggregation worlds are 
 formed, are diffused through space, is it not reason- 
 able to imagine that between these, perhaps sup- 
 porting them as well as separating them, is a subtle 
 animated vapour ? Heat, as is well known, causes a 
 re-arrangement of material particles, which may be 
 scattered or condensed according as the cosmic forces 
 operate upon them. This scattering or condensation 
 would occur at a different temperature in the case of 
 different particles, according of course to the original 
 properties of the molecules. Certain particles of the 
 cosmic vital steam, would, at a given temperature, 
 gyrate upwards and distribute themselves, while 
 others might approach one another and form a 
 vital crystal. This, growing by aggregation, might 
 become a spontaneous ovum, the product of evolution 
 and formifaction, containing potentially not only a 
 fully developed organism, but whole generations of 
 altering forms, every one of whose specific characters 
 might be defined at this very time by a sufficient 
 intelligence ! The rapid increase of physical energy 
 encourages the physicist in his attempts to forecast 
 the future, while it enables him to secure some frae-- 
 
 o 
 
 ments of the real which, but for his successful efforts, 
 would have been for ever lost in the infinite void of 
 unfathomable nothingness. 
 
62 VEGETABLE GERMS 
 
 SUPPOSED INFLUENCE OF VEGETABLE GERMS IN 
 CAUSING DISEASE. 
 
 TJic inajiner in zvhich tJicy might enter the Body. — 
 No wonder that many of the diseases of man should be 
 attributed to microscopic fungus germs so very small 
 that they could readily enter his organism by any of 
 the numerous pores all over his body. Particles so 
 minute could easily pass into his blood through the 
 soft mucous covering of his mouth or stomach, enter- 
 ing these recesses with food and water. They would 
 not insinuate themselves into the chinks between the 
 epithelial cells of his cuticle and move towards the 
 blood, as is possible in the case of bodies which 
 possess the power of active movement, like an amoeba, 
 or a white blood corpuscle, or a pus corpuscle, but 
 they would extend inwards, by growth and free multi- 
 plication in the very substance of the protecting 
 epithelium. Each new particle produced would thus 
 get nearer and nearer to the blood, which would at 
 last be reached by the growth of particle after particle 
 in advance. Becoming immersed in a medium 
 adapted for their nutrition, the germs which had 
 gained access to the blood would grow and multipl}- 
 very rapidly. Countless myriads of such germs 
 might circulate to all parts of the body. Multitudes 
 of these becoming stationary in the capillary vessels 
 of the cutaneous and mucous surfaces would increase 
 
THE CAUSE OF DISEASE. 63 
 
 there, and might give rise to the morbid phenomena 
 which characterise fever. 
 
 Since it has been shown that Hving germs of entozoa 
 a thousand times larger than these vegetable germs 
 may traverse man's textures, and pass long distances 
 through the tissues and organs of his body, until the 
 particular locality suitable for their development into 
 a higher stage of being has been reached, it is im- 
 possible to oppose to this notion of the entrance of 
 vegetable fungus germs any serious objection, at least 
 from this point of view. But at the same time, before 
 anyone who is acquainted with the facts, and reflects 
 carefully, will accept this doctrine, he will desire to be 
 satisfied upon many points which unquestionably 
 require elucidation. It is not sufficient to show that 
 such particles migJit enter the body in the manner 
 suggested. But it is necessary to prove not only 
 that they really do enter, but that they give rise to 
 the changes in the way which is suggested by the 
 theory in question. If the vegetable germs which 
 have been referred to are indeed the active agents, 
 we ought to be able to demonstrate them, for there 
 is no difficulty whatever in demonstrating closely 
 allied organisms where they do exist, as for instance 
 in the epithelial cells on the mucous lining of the 
 mouth, in which millions can be seen at any time. 
 
 Of the Vegetable Germs aetiially diseovered in the 
 
 fluids and tissues of the higher Animals during Life. — 
 
 In every part of the body of man and the higher 
 
64 VEGETABLE GERMS 
 
 animals, and probably from the earliest age, and in all 
 stages of health, vegetable germs do exist. These 
 germs are in a dormant or quiescent state, but may 
 become active and undergo development during life 
 should the conditions favourable to their increase be 
 manifested. Indeed, if the flow of fluid which persists 
 in the normal state in the ultimate parts of the tissues 
 as long as life lasts be stopped, changes take place 
 exactly resembling those which are occasioned in 
 dead tissues removed from the body, and kept at a 
 temperature of lOO degrees. As has been remarked, 
 '' decomposition " takes place, and, if this decomposi- 
 tion is not a consequence of the multiplication of the 
 vegetable organisms, it is at any rate certain that 
 the growth and multiplication of these bodies are 
 constantly associated with the change in question. 
 There cannot be a doubt that vegetable germs exist 
 in the internal parts of the body which would grow 
 under the circumstances supposed. 
 
 The higher life is, I think, everywhere interpene- 
 trated as it were by the lowest life. Probably there 
 is not a tissue in which these germs do not exist, nor is 
 the blood of man free from them. They are found not 
 only in the interstices of tissues, but they invade the 
 elementary parts themselves. Multitudes infest the 
 old epithelial cells of many of the internal surfaces, 
 and grow and flourish in the very substance of the 
 formed material of the cell itself l^ut the living 
 germinal matter of the tissues and organs is probably 
 
GERMS.— BACTERIA IN INTIKJOR OF THE BODY. 
 Pig. 23. 
 
 PLATE IV. 
 
 
 .ftr,^ 
 
 lamnar epithelium from the jejunum of a child who died of cholera. The small bodies in every part 
 the field and many of those m the epithelial cells themselves are bacteria and bacteiia $erms. These 
 are not pecuUar to cholera. They were alive when the specimen -was exanained. x TOO. p. 66. 
 
 Fig. 24. 
 
 Summit of one of the epithelial cells represented iu 
 Fig. 23. containing germs in the interior, a, thick sum 
 mit of the cell. 6, free bacteria germs. X 1300. p. 66, 
 
 Yvzi. 2f 
 
 Fig. 25. 
 
 
 L-ierma :u tiiood trom the hepatic vein ot a co^v which 
 died of cattle plague. The round bodies 6 are growing 
 red blood corpuscles still containing bioplasm. The 
 large body a is a white blood corpuscle. The blood 
 was quite warm when examined. X 2800. p. 66. 
 
 of an inch 
 
 Obstructed vessel, with bulgxngs, from 
 the summit of a villus Case 3. Cholera. 
 In the interior were bacteria, oil globules, 
 blood corpuscles, and the sporules of 
 fungi. X 700. p. 63. 
 
 Fig. 27. 
 
 
 o 
 
 ^ very small portion of one of the con- 
 tracted and altered capillartes from the 
 summit of a villus Cholera, x 2800. a 
 is a small particle which somewhat re- 
 sembled a sporule of a fungus. 66, minute 
 particles of very smooth material (grow- 
 ing bioplasm). Oil globules are also seen 
 in considerable numbers, p. i;6. 
 
 S. B, 1566. 
 
 1500. 
 < 2500. 
 
 X 700. 
 
 [To face p. 64. 
 
IN THE BLOOD AND TISSUES. 65 
 
 perfectly free from vegetable germs. Some are, 
 however, not uncommonly met with on the free 
 surface of the germinal matter, where its death and 
 conversion into formed material are taking place. So 
 long as the higher living matter lives and grows, the 
 vegetable germs are passive and dormant, but when 
 changes occur and the normal condition departs, they 
 become active and multiply. Millions are always 
 present on the dorsum of the tongue and in the ali- 
 mentary canal, but they remain in what may be 
 termed a germ or embryonic state. The normal secre- 
 tions poured into the alimentary canal prevent their 
 growth, and the nourishment comes to us instead of 
 being appropriated by them. But what happens if 
 some of these fluids be suppressed or changed in 
 quality.'* The bacteria, grow and multiply, and the 
 nourishment is no longer absorbed into our bodies. 
 In infants a little derangement in digestion will 
 entirely prevent the assimilation of the milk, which 
 remains in the intestines a source of irritation, until it 
 is expelled, serving only for the nutrition of bacteria, 
 which are found in countless multitudes in every 
 particle of it. If more milk be introduced it soon 
 undergoes the same change, and the child might, 
 perhaps, be starved by the persistent introduction of 
 fresh food. If food is withheld for a time, the alimen- 
 tary canal soon becomes emptied of its contents, and 
 regains its natural healthy action, a process which is 
 expedited, as is well known, by the administration of 
 
 F 
 
66 BACTERIA IN THE BLOOD. 
 
 some simple purgative, which excites the glands to 
 pour out secretion, and so the passage is cleared from 
 the stomach downwards. 
 
 In many very different forms of disease these germs 
 of bacteria, and probably of many fungi, are to be dis- 
 covered in the fluids of the body, but the evidence 
 yet adduced does not establish any connection be- 
 tween the germs and the morbid process. In Plate 
 IV. these minute organisms are represented in the 
 contents of the alimentary canal, and in the interior 
 of the epithelial cells of the mucous membrane of the 
 intestine in cholera. In the contents of the blood- 
 vessels of the same disease, and in the blood taken 
 almost immediately after death from the vessels of 
 animals destroyed by cattle plague and other fevers, 
 similar bodies have been found, Plate III, figs. 15, 
 16, 21, though probably not of exactly the same kind 
 in every case, Figs. 25, 26, 27. 
 
 As has been already stated, germs apparently 
 of the same nature as those figured in Figs. 23 and 
 24 from cholera, are invariably to be found in the 
 old epithelial cells of the mouth of healthy persons, 
 and not rarely in those from many other surfaces. In 
 the intestinal contents in various slight derangements, 
 they are common enough, so that we cannot but con- 
 clude that their presence is due rather to alterations 
 in the fluids consequent upon morbid changes, than that 
 they are thcmselv^es the cause of the disease. They 
 follow the morbid change instead of preceding it. 
 
BACTERIA IN SECRETIONS. 
 
 67 
 
 And the same observations may be made with re- 
 gard to the presence of bacteria in the blood of man 
 and animals destroyed by various diseases. 
 
 Sometimes these germs grow and multiply in a 
 secretion not perfectly healthy, before it has left the 
 gland follicles, and they have been detected in the 
 milk as it issued from the breast, in the saliva, in the 
 bile and urine, as well as in other secretions. It will 
 no doubt be said in all these cases, " the germs have 
 been introduced from without— they pass from the air 
 into the orifice of the duct, and thus make their way to 
 the gland. From this point they might readily pass 
 into the blood." But it is more likely they are in the 
 blood and in the tissues at all times. They are met 
 with in the blood especially, in some instances in which 
 there is no reason whatever for concluding they made 
 their way into this fluid shortly before they were found. 
 Nay, little particles may be seen in the circulating 
 fluid which 1 believe to be these lowly germs, ready 
 to grow and multiply whenever the conditions become 
 favourable. I have seen such particles adhering to 
 the surface of the white blood corpuscles, and also to 
 the red blood corpuscles. In the fibrin of an aneuris- 
 mal clot I have found active bacteria in vast numbers, 
 and have observed the erosion resulting from their long- 
 continued action so very short a time after death, that 
 I feel quite certain they had been living upon the 
 coagulated fibrin, and growing and multiplying during 
 several weeks previously, and yet they had not passed 
 
68 MALIGNANT PUSTULE. 
 
 into the general mass of the blood. But if this had 
 accidentally happened, they would have been destroyed 
 instead of multiplying-, if the blood was in a healthy 
 state. In cases in which these organisms have been 
 discovered actively multiplying in the blood, that fluid 
 must have already undergone serious changes, which 
 had rendered it unfit for the nutrition of the body. 
 
 I cannot agree with those who consider that we 
 have evidence in favour of the view that the bacteria 
 are really the active agents in cases in which the 
 blood has been shown to exhibit the properties of a 
 specific contagioics vims. The disease called malignant 
 pnstnlc has been attributed by Davaine (Comptes 
 Rendus, 1864) to the presence of bacteria in the 
 blood, but this observer does not prove that the 
 bacteria were the poisonous agents, and many cir- 
 cumstances render it probable that other matters 
 suspended in the blood constituted the real virus, 
 while the vegetable organisms were but harmless con- 
 comitants. Polli, Tigri, and many others, have 
 attributed typhoid fever and allied diseases to bac- 
 teria in the blood acting after the manner of ferments, 
 but the objections raised to the fermentation theory 
 have not yet been disposed of by those who advocate 
 this doctrine. Indeed, many authorities who have 
 attributed various phenomena to fermentation, and 
 have spoken of the fermentation theory, ha\e not 
 explained what they mean by the terms they employ, 
 and appear to have x'cr}- vague notions concerning the 
 
BACTERIA AND CONTAGIOUS DISEASE. 
 
 69 
 
 nature of the process called ''fermentation." This 
 word is often employed very carelessly, and like "irrita- 
 tion," "nutritive irritability," "stimulus," and a number 
 of other terms, is supposed to account for many pheno- 
 mena, although its meaning has not been defined, 
 and those who use it do not tell us what they mean 
 by it. 
 
 It appears then that bacteria germs grow and 
 multiply whenever a change takes place in the 
 solids and fluids of the organism which develops 
 compounds suitable for the pabulum of these living 
 bodies. From the fact that bacteria grow and 
 multiply not only in a few special fevers, but 
 in a great variety of different morbid conditions, 
 it is evident they have nothing to do with any 
 particular form of disease. All attempts to demons- 
 trate various constant species of bacteria, representing 
 different contagious diseases — and many attempts have 
 been made — have completely failed. There is greater 
 difficulty than would appear at first in testing the 
 matter experimentally, for it is probably impossible 
 to introduce bacteria in quantity into the blood of a 
 healthy animal without introducing at the same time 
 putrescent matters which by themselves would occa- 
 sion the most serious derangement. Active bacteria 
 introduced into a healthy wound or amongst the living 
 matter of healthy tissues, will die, although the most 
 minute germs present, which escape death, may remain 
 embedded in the tissue in a perfectly quiescent state. 
 
70 
 
 PROFESSOR LISTER'S VIEWS. 
 
 Before the bacteria can grow and multiply, the death 
 of the higher germinal matter must occur ; as long as 
 this lives, it, and the adjacent tissues, are freely per- 
 meated by healthy fluids, and will efficiently resist their 
 assaults. Much as I admire the interesting observa- 
 tions of Mr. Lister, and firmly as I believe the facts 
 as stated by him, I venture to doubt if the efficacy of 
 the treatment he so ably advocates is due to the pre- 
 vention of the entrance from without of these germs. 
 There are germs out of number "a'ithin, which would 
 grow and multiply in the wound, however perfectly 
 those outside were excluded, provided only the wound 
 itself were in a state favourable to the process. Bac- 
 teria germs appear in close cavities in the substance of 
 tissues during life and within the blood-vessels, as has 
 been already stated. The true explanation of the 
 undoubtedly beneficial action of the carbolic acid 
 antiseptic treatment may be very different to the 
 explanation offered by Mr. Lister. To me it appears 
 much more probable that the carbolic acid acts 
 directly upon the growth and multiplication of the 
 bioplasm of the part ; but this question shall be con- 
 sidered in another part of this memoir, after the 
 mode of formation of pus has been referred to. 
 
 The virulent poison which sometimes produces such 
 terrible results upon the healthy (}) organism in cases 
 of dissection wounds cannot be attributed to the pre- 
 sence of vegetable germs, for the period of its most 
 virulent actixit}- is very soon after death, but before 
 
FUNGI FR OM HUM A /V BIO PL A SM. 7 j 
 
 the occurrence of putrefaction and the development 
 of bacteria. 
 
 It has been assumed that the poison in question is 
 not developed until after death has occurred. But no 
 one has shown that if inoculation were effected while 
 the patient yet lived, the results would be in any way 
 different. There is, I think, no more doubt that such 
 poison is developed during life than that the poison 
 of small-pox, syphilis, and many other poisons which 
 are allied to these, and probably crrow and multiply 
 in the same manner, increase during life. 
 
 When putrefaction has actually set in, and bacteria 
 germs arebeingdeveloped in immense numbers, apunc- 
 tured wound is not productive of the dire consequences 
 which too often result if inoculation takes place within 
 a few hours after death. In fact, the real virus loses 
 its power when decomposition commences. Before 
 vegetable germs appear the virus is active ; soon after 
 these have been developed it is harmless. Its power 
 cannot, therefore, be attributed to the germs but must 
 be due to something else which continues to live and 
 remains active for a short time after death, and then 
 for ever disappears. The nature, mode of origin, and 
 multiplication of this active material will be fully dis- 
 cussed in the second part of this work. 
 
 Question of derivation of Fungus Germs from 
 higher Germinal Matter of another kind. — As has 
 been already remarked, lowly vegetable germs appear 
 in closed cavities in the substance of dead animal 
 
72 
 
 DERIVA TIOX OF FUNGI 
 
 and vegetable tissues. I have often seen them within 
 vegetable cells in which not a pore could be discovered 
 when the tissue was examined by the highest powers. 
 I have detected them in the interior of the cells in 
 the tissues of animals, and in the very centre of cells 
 with walls so thick and strong that it seems almost 
 impossible that such soft bodies could have made thair 
 way through from the surrounding medium. How 
 are we to account for the presence of living particles 
 in such situations 1 I have no doubt that ere long the 
 theory will be advanced that the living matter of the 
 cell, and the formed material of which it is composed, 
 become changed, and assume the condition of bio- 
 plasm of a lower grade of organisation. Thus, it will 
 be said, from one form of living matter a lower and 
 more degraded form is evolved, the lowly germs spring- 
 ing from the living matter of the cell itself. And it 
 might be alleged that the same forces which were once 
 active in the cell, become active in the new organisms 
 which grow and multiply after it has ceased to live. 
 
 Such simple germs are, as has already been 
 stated, from time to time found in the blood of 
 man, and to them various disturbances, ending in 
 death, have been attributed. They have been looked 
 upon as the germs concerned in the production of 
 disease and in the destruction of life much higher 
 than their own ; but the matter on which they li\e 
 has ceased to take part in the actions of the higher 
 life, ajid instead of being decomposetl into noxious 
 
FROM HIGHER BIOPLASM. 73 
 
 gases inimical to all life, it becomes appropriated by 
 the vegetable organisms, which grow and multiply 
 enormously. But these having continued to increase, 
 at length cease to multiply, and in their turn die. 
 The products resulting from their death may serve as 
 food for beings a little higher in the scale. 
 
 But we have now to enquire, how, if they are 
 not actually formed there, these bacterium germs 
 get into the interior of a perfectly closed cell. There 
 is no real difficulty in accounting for the entrance of 
 these germs through the cell wall ; for although no 
 pores may be visible even with the aid of the highest 
 powers, still pores sufficiently large to permit the 
 passage of such very minute particles as the germs are, 
 necessarily may exist, if not in the fully-formed state 
 of the cell, at least at an early period of its develop- 
 ment. If we examine, under the highest powers of 
 the microscope, fluid exudation which w^e know may 
 pass through membrane, and which, when examined 
 by ordinary means, appears perfectly clear, like water, 
 we frequently find in it minute particles of living 
 matter. By the 5L the apparently clear fluid rotating 
 round the cells of vallisneria is resolved into multi- 
 tudes of extremely minute particles of colourless 
 matter, or bioplasm, every one of which possesses the 
 power of moving, and is alive. There is, then, nothing 
 improbable in the supposition that minute germs might 
 pass through the cell wall with the pabulum. They 
 would remain in the cell wall or tissue perfectly 
 
74 
 
 DISEASES DUE TO 
 
 inactive and dormant as long as the cell remained 
 vigorous and healthy, but sooner or later, if not from 
 disease, from old age, changes must occur by which 
 a state of things results which is favourable to the 
 germs whose turn invariably comes at last. These 
 grow and multiply and live upon the dead germinal 
 matter and the altered and softened formed mate- 
 rial of the cells. We must, in the absence of positive 
 demonstration, hesitate to accept the doctrine that 
 the lowest organisms may result from degradation of 
 the living matter, which at one time formed a part of 
 a higher being. But we may refuse to accept the state- 
 ments which have been made as to the direct conver- 
 sion of the fibrillae or discs of striped muscle into 
 bacteria, because such assertions are contradicted by 
 well-known facts. From the red blood corpuscles may 
 be made bodies which might be mistaken for bacteria ; 
 nay, if the most practised observer were to examine 
 one of these bodies only by itself, he might easily be 
 deceived. The little beaded filaments exhibit move- 
 ments which, though differing from the movements of 
 the bacteria, would certainly be mistaken for them 
 by an unpractised observer. But it ought not to be 
 necessary to state, that in microscopical research mere 
 resemblance in external form and general characters 
 should not be accepted as proof of identity of nature 
 any more than in ordinary observation. 
 
 Of Diseases knoivn to be due to Vegetable Orgauisins. 
 — The diseases of man and the hiijhcr animals, known 
 
VEGETABLE ORGANISMS. 75 
 
 to depend upon the growth and development of 
 vegetable organisms, are local affections confined to a 
 part of the body not involving the blood, while for 
 the most part, the different forms of contagious fevers 
 are general affections in which the whole mass of the 
 blood, and, in some cases, every part of the body, is 
 affected, and is capable of communicating the disease. 
 In fungus diseases, the structure of the v^egetable 
 organism can be made out without difficulty, and the 
 vegetable examined in every stage of its development. 
 The microscopic characters are distinct and definite 
 enough. No such success attends our efforts to prove 
 that vegetable organisms are truly the active agents 
 in contagious fevers. And in many of the diseases 
 which are at this time considered to be actually due 
 to the multiplication of vegetable germs, it is doubtful 
 if the tissues and organs invaded were perfectly 
 healthy at the time of invasion. For all persons ex- 
 posed are not attacked, and if not in all, at least in 
 the great majority of instances know^n, the view that 
 a morbid change must occur before the tissue is in a 
 state to be invaded by the fungus growth, is tenable. 
 In fact, it has been already shown that the fungi 
 which commonly grow on the surface, and in other 
 parts of the body, do not produce disease. The 
 germs of fungi may remain perfectly passive and 
 quiescent in healthy textures, growing and multi- 
 plying only in those which have already deteriorated 
 in consequence of disease or old age. The growth of 
 
7 6 DIFFICUL TIES IN A CCEPTING 
 
 the vegetable germs, therefore, instead of occasioning 
 the disease, may be dependent upon the occurrence 
 of phenomena altogether different. There are, T 
 think, very few morbid conditions that are unques- 
 tionably solely due to the growth and multiplication 
 of vegetable fungi. 
 
 Some difficulties wJiicIi prevent its from accepting 
 the Vegetable Germ Theory of Disease. — If con- 
 tagious diseases are due to the entrance into the 
 organism of such minute vegetable germs as those 
 described, is it not wonderful that any one escapes 
 disease } Multitudes of germs cf different species, as 
 numerous as are the contagious diseases from which 
 we suffer, must, if this theory be true, surround us. 
 And yet the fungus germs, which are to be detected 
 easily enough, and which indeed do exist in great 
 numbers, are not known to cause any disease. Still, 
 upon this view these must be the disease-producing 
 particles, for they are the only vegetable germs that 
 have been discovered. ' Passing into our lungs with 
 every inspiration, entering our stomachs with our food 
 and drink, everywhere in contact with our cuticle, in 
 the chinks of which they might grow and multiply, 
 these fungus germs must, one would think, pass in 
 vast numbers into our blood, and be carried to every 
 part of our bodies. Contagious diseases ought, there- 
 fore, to be more common than they are, and escape 
 from attack should be almost impossible. 
 
 Vegetable fungus germs are to be met with in every 
 
FUNGUS GERM THEORY. 77 
 
 country, and there are probably few substances in or 
 upon the earth which are entirely free from them. If 
 their introduction alone is sufficient to produce disease, 
 one malady ought to follow another, until the cata- 
 locfue of contagious diseases becomes exhausted, or 
 the organism is destroyed. But many fungi even 
 form articles of diet and medicine, and many animals 
 devour whole forests of living, growing fungi in every 
 mouthful of food they take. Of these not a few 
 are destroyed by the fluids poured into the alimentary 
 canal, digested, and the products appropriated by the 
 organism. The animal, in fact, lives upon them, in- 
 stead of the fungi living upon him ; and in various 
 cases in which certain fungi do actually invade our 
 tissues, the evidence of change in these last having 
 occurred prior to the development of the fungi, is 
 sometimes so distinct, that the conclusion is irresistible, 
 that, so far from the fungus attacking a healthy struc- 
 ture and damaging it, the structure itself had dete- 
 riorated and changed, or had undergone morbid 
 derangement ere it was invaded. By decay it would 
 appear that it had become converted into material 
 adapted for the nutrition of the fungi, the growth of 
 which had been effectually resisted as long as the 
 tissue remained healthy. If this be so, the fungi 
 cannot be regarded as the cause of the disease, any 
 more than the vultures which devour the carcase of a 
 dead man can be looked upon as the cause of his death. 
 Vegetable germs exist in countless multitudes 
 
y 8 DIFFICUL TV IN A CCEPTING 
 
 where contagious diseases arc unknown, as well as 
 where they are rife. Their sparing or abundant multi- 
 plication varies with altering temperature, moisture, 
 and other conditions, and does not always coincide 
 with the fluctuation of disease. If vegetable germs 
 are the seeds of disease, the seeds are everywhere, 
 while in many instances the diseases are remarkable 
 for being particularly local. If these be disease germs, 
 they are present in all climes, while the diseases them- 
 selves are limited to certain definite regions. We 
 may cultivate the vegetable germs without producing 
 disease, and disease may be raging while there is no 
 evidence of a corresponding increase of the vegetable 
 organisms upon which it is supposed to depend. If 
 vegetable organisms are really the contagious particles, 
 it is hopeless to attempt to protect ourselves from their 
 invasion, and to talk of extirpating them would be 
 absurd, for were a particular species destroyed over 
 half England to-morrow, the next breath of wind would 
 bring multitudes of germs to take the place of those 
 which had been swept away. Nor should we stand 
 any chance of escaping their ravages, by leaving our 
 dwellings in cities, and taking up our abode in the 
 country, or by taking refuge even in the highest 
 mountains, or other sequestered places far away from 
 the haunts of men. And if fungi are developed spon- 
 taneously, and disease germs consist of fungi, the 
 state of things is still worse, as in that case, if eradi- 
 cation were possible, it would be idle to attempt to 
 
FUXGUS GERM THEORY. 
 
 79 
 
 effect it ; for if all in existence at any one time were 
 utterly destoyed, new ones would soon spontaneously 
 emanate from the non-living, and we should be in as 
 bad a plight as before. ]\Iinute vegetable germs, re- 
 sembling those to which disease has been attributed, 
 are everywhere, though their presence may easily 
 escape observation. If, however, the pabulum 
 adapted for them be present, and the conditions 
 favourable to their development, they soon grow and 
 multiply, and abundant evidence is afforded of their 
 presence. 
 
 In answer to the observation, that if these fungus 
 germs constitute the morbid material of contagious 
 diseases everyone should be attacked, it might be 
 said, " the organism is not always in a state favourable 
 to invasion, and that it is only in exceptional cases, 
 or in exceptional states of health, that the presence 
 of fungi affects us deleteriously." To this the reply 
 might be that "there are many kinds of conta- 
 gious matter which give rise to characteristic effects 
 with unerring certainty." The introduction of as 
 much as would adhere to a needle point into the body 
 of a healthy subject, acting without a chance of fail- 
 ure. If, therefore, we accept this vegetable germ 
 theory of disease, we must hold that there are certain 
 fungi which affect all men in all conditions of health, 
 but which are at present undiscoverable, while other 
 fungi, which are very easily discovered, are not known 
 to affect the organism in any condition of health ; 
 
8o ^'O VEGETABLE ORGANISMS 
 
 and that other fungi, also unknown at this time, 
 exist, which are only able to produce their effects in 
 organisms changed by certain previous actions for 
 their reception, — and this, in spite of the fact that no 
 connection whatever has been shown to obtain between 
 any contagious disease and any kind of fungus germs. 
 
 But yet in favour of such a doctrine it might be 
 urged with truth, that some parasitic organisms affect 
 all indiscriminately, while others require certain preli- 
 minary changes to be carried out before the various 
 parts of the organism they delight in are adapted for 
 their habitation and are rendered favourable to their 
 increase. It must not, however, be forgotten that 
 parasites which are known exhibit at one or other 
 stage of existence certain well-marked characters by 
 which they may be recognised with the utmost cer- 
 tainty, and this is especially the case wdth parasitic 
 vegetable organisms, many of which can be grown 
 artificially without much difficulty, and studied in the 
 several different stages of their development. 
 
 Those who look with partiality upon the vegetable 
 germ theory of disease should consider how the absence 
 of any bodies like vegetable fungi in animal fluids and 
 solids, proved by experiment to possess active infectious 
 properties, is to be accounted for. Not only is it the 
 case that vegetable organisms arc not to be found 
 in the perfectly fresh virus when it is most active, but 
 no specific form of vegetable growth can be dc\-eloped 
 from the particles ^^'hich do exist, as would almost 
 
IN CONTAGIOUS VIRUS. 8i 
 
 certainly be the case if the particles present in the fluids 
 had been vegetable germs. Every kind of parisitic 
 germ known is capable of undergoing development 
 into a body having definite and well-marked charac- 
 ters. Though in the germ stage different species 
 would resemble one another, as indeed is the case as 
 regards creatures much higher in the scale, they do not 
 constantly retain indefinite characters. And when the 
 germs are so minute as to be readily passed over in 
 ordinary microscopical examination ( lOO to 300 ), by 
 the aid of higher powers excessively minute vegetable 
 germs may be recognised with certainty, if not by 
 their form., at least by their mode of multiplication. 
 The germs of many animal parasites are also to be 
 distinguished by careful examination, and from what 
 we know of the life history of these, we should not be 
 justified in attributing contagious diseases, in which 
 every drop of animal fluid in the body possesses con- 
 tagious properties, but for a fixed and definite period 
 of time only, to germs of a new class of animal or 
 or vegetable parasite of which not one species has 
 been discovered, and the germs of which are even 
 less than yooVoo" ^^ '^^ mch in diameter. It may, 
 therefore, be affirmed that the matter which forms 
 the active virus or poisonous material does not 
 exhibit the properties of any vegetable or animal 
 parasitic organism yet discovered and identified. 
 Neither can any organisms, having special and pecu- 
 liar characters, be developed from any definite virus. 
 
 G 
 
VEGETABLE GERM THEORY. 
 
 Will, then, the advocates of the vefjetable jjerm 
 theory of disease maintain that this view ought to be 
 accepted simply because, in some of the discharges 
 and fluids of diseased animals or man, vegetable 
 germs are to be found, in face of the fact that similar 
 
 C!:erms^are to be detected in all sorts of harnilc 
 
 t> 
 
 ss 
 
 animal fluids and even in foods zvhicJi are taken and 
 digested! As soon as fungi have developed them- 
 selves freely in animal fluids possessing special con- 
 tagious properties, such as vaccine lymph, or small- 
 pox lymph, the specific characters of the poison be- 
 come weak or disappear. This seems to negative the 
 view under consideration. In answer it might be 
 urged that, " because a few vegetable organisms ex- 
 cite the disease, it does not therefore follow that a 
 multitude should be more potent, — rather the con- 
 trary ; for a few might retain their vitality and propa- 
 gate themselves, while, if a great number were present, 
 the pabulum necessary for their activity would be in- 
 sufficient, and all would perish!" The advocates 
 of the theory may be permitted to enjoy an}- ad- 
 vantage that can be derived from this sort of argu- 
 mcnt ; for, however cleverly it may be put forward, 
 most people who know the facts of the case will be 
 of opinion that the vegetable organisms when present 
 arc but accidental concomitants, and that a potent 
 poison, not of the nature of a vegetable germ, is pre- 
 sent in the animal fluid or solid in which the contagious 
 properties are known to reside. 
 
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