ST2 7 THE GERM THEORY OF DISEASE. A Paper read before the Irish Central Veterinary Medical Society, April 5th, 1883. BY JAMES LAMBERT, F.R.C.V.S., Inspecting Veterinary Surgeon for Ireland , Army Veterinary Department. PRICE ONE SHILLING Jtmrbon: BAILLIERE, TINDALL, & COX, KING WILLIAM.STREET, STRAND. 1883. THE GERM THEORY OF DISEASE.* BY JAMES LAMBERT, F.R.C.V.S., INSPECTING VETERINARY SURGEON FOR IRELAND, ARMY VETERINARY DEPARTMENT. Mr. President and Gentlemen, —Our subject this evening is the Germ Theory of Disease, and a more important doctrine, in its bearing on the health and welfare of mankind and the domesticated animals, has never been given to the world. It is disturbing and exercising both the scientific and the practical mind, and revolutionising our ideas of the consideration^ and treatment of disease. Every day new facts connected with it are brought to light, and every week hundreds of converts are en¬ rolled in its ranks. Its greatest aid is the microscope, which is the true Columbus of medical science, and which is continually bringing new worlds into our ken. We must not, however, be too sanguine about the Germ Theory of Disease, and we must learn to study it patiently, and without too much enthusiasm, for many and weighty matters have yet to be investigated and confirmed. At present, how¬ ever, we may reasonably say that we have in this theory already sufficient groundwork to inspire us with boundless hope. To the veterinary profession it is extremely gratifying to know that Professors Chauveau and Toussaint—two French veterinary surgeons—have taken most prominent and leading parts in its initiation and elucidation. Professor Chauveau is acknowledged to be one of its foremost pioneers, and of him Dr. Charles Cameron, M.P., in his very excellent paper on the “Microbes of Disease,” says: “Monsieur Chauveau, a veterinary surgeon of Lyons, who first demonstrated that infections were not liquid or gaseous, but particulate, and whose many invaluable researches are far too little known in this country.” * A paper read before the Irish Central Veterinary Medical Society in the Lecture Theatre of the Royal Dublin Society, on the 5th April, 1883. M. Toussaint is famous for many discoveries in this field, amongst others of the bacterium or microbe which produces Fowl Cholera, nor must we forget the great services of Professor Bouley, the distinguished Director-General of the French Veterinary Schools. We might also name many other Continental veterinarians, who are noted as original experi¬ mentalists in connection with the Germ Theory. We may, however, well quote what Dr. Charles Cameron, in an address to the Social Science Congress, in 1881, said about foreign mem¬ bers of our profession:—“ It is their investigations into the diseases of the domesticated animals which have enabled the veterinary surgeons of France, within the last few months, to make such preponderating contributions towards the solution of questions vitally affecting, not merely those animals, but man¬ kind.” Dr. Cameron, in the same address, urged the institution of Chairs of Comparative Medicine and Pathology, and the desirability of carrying this suggestion into effect must be very apparent to all careful students of our medical literature. Coming now to our British Islands, we have investigators who have made valuable contributions towards throwing light on the Germ Theory, and we may name Dr. Lionel Beale and Drs. Burdon-Sanderson and Klein, and Mr. Cheyne, as the most prominent. Professor Lister’s great discovery of antiseptic surgery—an outcome of the Germ Theory—has been of incal¬ culable benefit to mankind. In reading about researches connected with the doctrine we are considering, it will not fail to strike you how rarely any British names are mentioned. In some measure this may be, speaking for the moment of the medical profession, that any dis¬ coveries it may have made are dwarfed by the greater ones of the Continental investigators; nor must we forget under what restrictions and difficulties experiments on animals are here carried on. Professor John Gamgee and Mr. George Fleming, two veterinary surgeons, have been prominent in spreading information about contagious diseases, and Mr. Fleming is of European reputation as one of the foremost of comparative pathologists. But why do not the veterinarians of the United Kingdom come more to the 5 front in these matters ? The answer is not far to seek. On the Continent the veterinary profession receives great State aid and patronage, and is therefore abreast of the foremost as one of light and leading. In our own country it receives no State aid. Let that be duly given, and I have no doubt that it would soon equal all others in this and kindred matters which we have now under consideration. That it receives no State aid is, we believe, mistaken policy, for such assistance would be quickly repaid a hundred-fold. That the veterinary profession of the United Kingdom has, by its own unaided exertions, done such incalculable services to the country, redounds to its everlasting credit. The Germ Theory of Disease is so vast a theme, that we can only, in the limited time at our disposal to-night, briefly notice its most interesting features, and glance at some of the most important diseases of our domesticated animals to which it applies. I will endeavour to put what I have to say in plain language, and free from what are, to very many people, unintelligible words. Dr. Aitken, in his “ Outlines of the Science and Practice of Medicine,” gives the following excellent definition: “ The Germ Theory holds that each specific disease has a specific poison- germ, which lives, grows, and has a being specifically distinct from each and all other germs.” By a specific disease we mean one which has its own peculiar characters, which distinguish it from all other diseases. As an advocate of the Germ Theory, I will at once express my belief that every communicable, or transmissible, or con¬ tagious, or infectious, or specific disease depends on living organisms for its production and development. Permit me to say here, that throughout this paper I shall often use the words “ contagion ” and “ infection ” as conveying the same meaning. It is becoming recognized that all specific and contagious diseases are produced by a minute living organism—a parasite —supposed to be of low vegetable life, and that this parasite cannot be spontaneously generated, for, as Professor Tyndall says, “ As surely as a thistle rises from a thistle, as surely as the fW romes from the At. the sraoe from the grape, the thorn from BACTERIA or MICROBES. @ @© ©< 8 > @ Micrococcus, single and double. Micrococci are found in Small-pox, Erysipelas, Scarlet Fever, in putre¬ faction, in Septic diseases, and in Contagious Pleuro-pneumonia of cattle. Chains of micrococci. Zooglsea. A large number of micrococci collected together in a round mass. Tubercle Bacillus and Glanders Bacillus. Very small, not longer than half the diameter of a red blood corpuscle (a). Vibrio, found in putrefying pus; also in Septicaemia and Pyaemia. Spirillum, found in Relapsing and some other Malarious Fevers. Yeast Plant, developed by gemmation, or budding, or fission, one cell from another. BACTERIA OR MICROBES. s c£ Bacillus Anthracis, the Anthrax Bacillus, present in Splenic Fever. It is a large bacillus—compare it with the blood globule (a). A bacillus of similar form is also present in putrefaction. Bacillus dividing by transverse fission or segmentation. Matted rods of Bacillus Anthracis, extending in rows between fibres of sub¬ cutaneous tissue. Natural size of rods u*Wth to nrWth of an inch in length.— Carpenter. A© ( 2 > © <§> <§> C^> B Life History of Bacillus Anthracis. (a) Division of spore into four sporules. (b) Sporule developing into a rod. (c) Increase of rods by segmentation. (d) Filament produced by lengthening of rod. (e) Development of spores within filament.— Ewart . The Bacillus Anthracis therefore multiplies by transverse fission, and by spores, or seeds, or germs, whichever they may be called.—J. L. 8 the thorn, so surely does typhoid virus increase and multiply into typhoid fever, the scarlatina virus into scarlatina, the small¬ pox virus into small-pox. What is the conclusion that suggests itself here ? It is this—that the thing which we vaguely call a virus, is to all intents and purposes a seed.” Under the head of “Germs,” Bacteria of all kinds are included, and under the head of Bacteria are included bacilli, micrococci, vibrios, spirilla, etc. On the Continent these organisms are usually called Microbes, which is a much better term. I will now describe these disease-producing agents. There is first the bacterium, or bacterion, or bacillus, Greek and Latin words sig¬ nifying “ a little rod.” The Bacteria, then, are minute, rod- shaped bodies, which, in the diseases they produce, are found in the blood, fluids, and tissues of the body. They multiply them¬ selves with great rapidity by what is called transverse fission ; that is, one divides into two or more, and so on, and they also multiply by giving origin to spores, or germs, or seeds—three words here meaning the same thing—which develop into the likeness of the parent-organism. 'J Bacteria are very small, about the -^g-th of an inch in length, and many are even smaller. They are about the ^J^th °f an inch in diameter. If you look at the diagram, and compare them, you will see that a bacterium is very often not as large as a red blood-corpuscle. Now, it is calculated that if placed edge to edge, ten millions of red blood-corpuscles would lie on a square inch of surface ; yet, as we have just seen, many of the bacteria are much smaller than the blood-globules. This en¬ ables us to readily understand how germs are wafted about in the atmosphere, which may thus be—and doubtless often is—a disease-carrier. Then there is another disease-producing agent, or bacterium, called the micrococcus, which is an exceedingly minute round organism, and the diplococcus, a kind of double micrococcus. There is the vibrio, a sort of lengthened cell, which often moves about in a lively manner. There is also the spirillum, which is the cause of Relapsing Fever. There are numerous other microbes which it is unnecessary to mention here. Under the microscope many of these organisms are seen to 9 move about in different ways. All of them under favourable conditions rapidly multiply themselves. You will naturally ask, are they animals or vegetables ? The boundary-line between animal and vegetable life is extremely shadowy ; however, it is considered that they are of a low vegetable type. The bacteria are easily killed by heat, and by some chemical solutions, but their spores, or germs, or seeds—whichever you like to call them—are very tenacious of life. Some of the spores may be boiled for two or three hours without being killed, and if dried, they will keep for a long time, for months or even years, and show that they are still alive when they meet with suitable conditions. It should here be said that bacteria of different kinds are almost everywhere ; in our food, and water, and milk, and other fluids, and in the atmosphere. We also know that the putrefac¬ tion of animal and. vegetable substances is caused by bacteria. Keep these away, and those things will not rot. Professor Huxley says, “All the forms of putrefaction which are under¬ gone by animal and vegetable matters are fermentations set up by bacteria of different kinds ; therefore, putrefaction is a con¬ comitant, not of death, but of life.” Septicaemia, or blood- poisoning, and Pyaemia also depend on certain microbes being morbidly at work in the body. I have already expressed the belief that all transmissible and contagious diseases are caused by living organisms, and that each disease has its own particular germ, which only produces its like, just as we see wheat produce wheat or an acorn an oak. And we may reasonably believe that each specific or particular kind , of germ requires for its propagation suitable nourishment and favourable conditions, without which it will sooner or later perish. And it is highly probable that each kind of specific germ has, when it enters the body, a favourite locality, or resting-place, or nest, where it can best multiply itself. We may here remark that disease-germs can enter the blood-vessels, and even pene¬ trate the white blood-corpuscles. It is likewise probable that disease-germs must not only enter the body to produce their effects, but also that the body must afford them suitable condi¬ tions to enable them to multiply, and so powerfully attack their ID host. For this reason, perhaps, strong healthy animals often resist infection or bear it well, while the weak and debilitated fall an easy prey and succumb. We may ask, how is it that the bacteria attack the body, derange its functions, causing it to be ill, and then, after a time, frequently cease their operations ? May we not reasonably think that the body often recovers because the parasites have exhausted the suitable food and conditions for their existence, or, in other words, find the body uninhabitable, and perish ? To speak of recurring fevers, like ague and some others, the very probable suggestion has been offered, that successive crops of bacteria come to maturity, each coming to maturity being attended by a return of the illness. If not, how can we explain the periodical recurrence of some fevers; for instance, the tertian and quoti¬ dian, and the daily hectic access of Phthisis ? Dr. J. E. Pollock, in his recently-delivered lecture on the Modern Theories and treatment of Phthisis, speaking of this recrudescence, says: “ Chemical ferments would not act so, but would work through the whole system at once, and either kill the patient or exhaust themselves, by finding no more material to work on.”— Lancet , March, 1883. But very many observers, whose opinions are entitled to the greatest consideration and respect, will not yet give in their adhesion to the Germ Theory of Disease, and they stoutly maintain that the germs are a disease-product, or consequence, and not the cause. Some hold that what we call disease-germs may occur in the body without previous infection, and as a result of morbid processes ; and some maintain that they exist in all living and healthy animals, and that they are not causes of disease, but only become so when abnormally increased. As we proceed you can form your own opinions ; but I may at once say, that when we find that, if we take infected fluid and filter away the germs, it becomes harmless, it is difficult to look upon them as otherwise than the disease-producing agents. In rela¬ tion to this, it may be stated that M. Pasteur has lately published a rather remarkable experiment. He suspended a tube vertically in one of the cellars of the Observatoire at Paris. This tube contained an exalted culture of Splenic Fever virus, or bacteria. After a time the bacteria and their spores settled at the bottom of the tube. He first inoculated with the top liquid, and it proved inoffensive; then he inoculated with the lower liquid, and it killed the animals experimented upon. This is a suffi¬ ciently striking experience. He also adds that M. Vulpian, the physiologist, lately informed him that he had made the interest¬ ing observation that the filtration of a poisonous solution of strychnine can make the liquid harmless .—Revue Scientifique , 20th January, 1883. Disease-germs being, as we have seen, so exceedingly small, can be readily carried in the atmosphere, and so be deposited in wounds, or they may he breathed into the lungs, as in Scarlet Fever and Measles. Or they may be swallowed in the food or drink, as in Cholera, Typhoid Fever, and Dysentery. A third way of conveying infection is by bites, as of a rabid animal, or punctures, as in snake-bite, or by actual contact of the healthy with the sick, allowing germs to get access through the skin, and, as is also believed, sometimes by a rabid dog licking the hand. In describing the Germ Theory, it has become customary to select the action of the yeast-plant as an illustration. When the yeast germs, which are very small ovoid vegetable bodies, are added to any saccharine solution which is kept warm, they at once begin to rapidly develop and multiply themselves, and the result is what is called fermentation, and alcohol and carbonic acid are formed. Now mark this, a saccharine solution will not ferment unless yeast gets into it. If you filter yeast so as to catch the germs and then add its fluid without them, the saccharine fluid will not ferment. If you add a little yeast to saccharine fluid, then boil it and exclude air, unless it has pre¬ viously passed through cotton-wool, it will not ferment, because boiling has killed the yeast. So, as Professor Huxley says, “ These experiments afford evidence, 1st, that there is something in the yeast which provokes fermentation; 2nd, that this some¬ thing may have its efficiency destroyed by a high temperature ; 3rd, that this something consists of particles which may be separated from the fluid which contains them, by a fine filter; 4th, that these particles may be contained in the air, and that they may be strained off from the air by causing it to pass 12 through cotton-wool” (“Practical Biology.” Article, Yeast). We thus see that the yeast germs behave very like the disease- producing bacteria we are now considering. The cultivation of silkworms in France is a great source of wealth. In 1865, a disease was committing severe ravages among them. M. Pasteur was requested to investigate it, and discovered that it was caused by microscopic living organisms. We have not now time to describe how after five years of patient observation M. Pasteur showed the silk-growers what caused the disease, viz., microscopic living parasites, which invaded the silkworm's body, but he also pointed out to them the way to stamp out the malady by breeding the worms only from un¬ infected eggs. The successful result of his investigations was gratefully and duly acknowledged. In 1879 Professor Toussaint, of the Toulouse Veterinary School, discovered the bacterium of Fowl Cholera, a disease which annually causes great havoc in the poultry yards of France. This discovery turned M. Pasteurs attention to the malady. He cultivated the bacteria which caused it in suitable fluids, and in doing so found out what was indeed important, viz., his method of attenuating bacteria, or as he calls them, “ microbes.’* But before going further let us examine the process at some length, as it will show what M. Pasteur and his disciples mean by “ cultivation.” He took a minute drop of the blood of a fowl about to die of Chicken Cholera, on the end of a delicate glass rod, and put it into pure chicken broth, of course excluding all air germs, and having previously by effectual means made it sterile, or, in other words, barren, or free from germs. Then the chicken broth into which the infected drop has been introduced, is placed in a temperature of25 Q to 35 0 C. or77 c to 95° Fahr., and it soon becomes cloudy from the multiplication of the microbes of the infected drop. The microbes are shaped like the figure 8. From the vessel in which this first cultivation has been made he takes another very small drop, not more than can be carried on the point of a glass rod as sharp as a needle, and touches with the point another vessel of pure and sterilized chicken broth. This in its turn becomes cloudy from the rapid multiplication of the introduced microbes. You deal in the same way with a third cul- *3 ture vase, with a fourth, and so on, up to a hundredth, or even a thousandth with the same results. Now you will find that if you inoculate with even the hundredth or the thousandth of these culture preparations you reproduce the original disease as strongly and as virulently as ever. These culture preparations have been thus far made one after the other without interval. Now let us suppose that we allow intervals between each culture ; say that between the hundredth and the hundredth-and-first we allow the liquid to rest a fortnight, or more, even up to ten months. If we compare the virulence we shall find that each delay is followed by a weakening of the next culture, so that, if we now inoculate, the virus is not so powerful. With the •cultivation thus obtained by an interval we make another, and we find that each successive interval causes a weakening of the powers of the disease-producing microbe, and we therefore per¬ ceive that it is possible to prepare a culture of varying degrees of virulence. We can thus by successive cultivations with inter¬ vals between each, weaken the powers of virulence of the microbe to any degree we wish, and at last we have it fit for what M. Pasteur calls " vaccination ” with no ill-effects, and yet it confers immunity from another attack of the disease. It is necessary to note that, if we have arrived at a certain degree of strength of the microbe, and the cultures are still conducted without intervals, that strength is maintained ; but given another interval, and weakening ensues. To recapitulate in a few words, then ; if each cultivation is carried on without intermission we have the same strength of the bacteria kept up, but give intervals between each cultivation and they are gradually weakened or attenuated,” until at length they lose their virulence, and a little further, to use M. Pasteur’s own words, “we touch the principle of vaccination.” What causes the weakening, or, as M. Pasteur calls it, the *“ attenuation ” of the bacteria or microbes produced by cultiva¬ tion ? He ascribes it to the oxygen of the air, and he continues : “ The oxygen of the air would seem to be a possible modifying agent in the virulence of the microbe of Fowl Cholera, that is to say, it may modify, more or less, the facility of its development in the bodies of animals.” He asks, “ May we not here be in 14 the presence of a general law applicable to all kinds of virus ? ” and he goes on to say, “ We may hope to discover in this way the vaccine of all virulent diseases.” To give a resume of the principal points we have noticed, we may say :— 1. That all transmissible, and very probably many—if not all— specific diseases are produced by living organisms. 2. That most of these diseases are caused by microscopic organisms, collectively called microbes or bacteria, which may be of different shapes, such as round, or rod-like, or oblong, or spirally coiled, or figure of eight, etc. I have just said, “ most transmissible diseases,” because there are transmissible maladies, such as Measles in the pig, and Mange, for instance, and others, where a microscope is scarcely necessary to detect the disease-producing organism. 3. That the bacteria are supposed to be of low vegetable life, that they are more or less capable of movement, and that they have the power of rapidly multiplying themselves when they meet with suitable conditions. 4. That their spores, or germs, or seeds, whichever we like to call them, are very tenacious of life, but that their parent- organism, the bacterium, is readily destroyed by a comparatively low temperature, very often as low as 140° Fahr. It is a subject for great surprise to some people that contagious maladies break out long after the original disease has left a locality; but if we conceive the germs or seeds as readily springing into life, like a grain of wheat, for example, when they meet with suitable con¬ ditions, we shall perceive that there is nothing of the marvellous about the matter, nor is there any absolute necessity to fall back upon spontaneous generation for an explanation. 5. That bacteria are so extremely minute that they, and also their germs or spores, can be very readily carried about in the atmosphere. The greatest attention is invited to this observation as bearing upon outbreaks of contagious diseases amongst men and animals. 6. That each transmissible disease has its own particular living organism which cannot be spontaneously generated. When we look at the history and progress of contagious and 15 infectious diseases, and when we see that there is a period of incubation or hatching between the exposure to infection and the manifestation of the malady, we presume that the disease- producing organisms are then multiplying themselves until they become so numerous as to make their operations apparent. In short, it is difficult, in the light shed by the germ theory, to conceive how these diseases can be produced in any other way. Some of the principal diseases of the domesticated animals, due, we may assume, to the presence of bacteria or microbes are, to employ the common names, Cattle Plague, or Rinderpest; Splenic Fever, a form of Anthrax; Quarter-ill, or Symptomatic Anthrax ; Horse Sickness in South Africa, a form of Anthrax; P'oot-and-mouth Disease, Contagious Pleuro-pneumonia of cattle, Texas Fever of cattle, Tuberculosis, Variola, or Small Pox; Glanders and Farcy, Influenza in horses, Rabies, Distem¬ per in dogs, Swine Plague; and there are, of course, many others. As it is impossible this evening to notice all the above-named maladies in the time at our disposal, I will only offer remarks on what at present appear to us the most important and practical, viz., Splenic Fever, “ Horse Sickness,” Tuberculosis, Foot-and mouth Disease, Contagious Pleuro-pneumonia of cattle, Glanders and Farcy, and Rabies. Let us begin with Splenic Fever, which is a form of Anthrax, the most widely diffused disease of our globe. M. Pasteur, after his success with Fowl Cholera, turned his attention to Splenic Fever, or Charbon, as it is commonly called in France, and which annually causes enormous losses in cattle and sheep in that country. It is now a rare disease in England, but centuries ago it was very common and destructive. It depends on the presence in the body of a bacterium called the Bacillus Anthracis, and is a contagious malady. M. Pasteur cultivated the Bacillus Anthracis under the influence of oxygen, and it was thereby so weakened or “ attenuated ” that it has been by him largely used for protective inoculation, with, he firmly believes, most satisfactory results. He also believes that this “vaccination ” protects against natural attacks of this awfully destructive Splenic Fever, but his conclusions are vigorously contested by the celebrated German physician and experimentalist, M. Koch. A rather bitter contro- i6 versy is going on between them, but at present the weight of argument seems to be greatly in favour of M. Pasteur. Much good may arise in various ways from this conflict of opinion. We must not forget to say, that M. Pasteur ascribes an important part, in sometimes causing Splenic Fever, to earth¬ worms, which he has proved bring up disease-spores, or germs, from the deeply buried carcases of animals dead of the malady > •even for months and years after interment He has demonstrated that such germs being swallowed with the food by healthy animals grazing over the graves, have communicated Splenic Fever. This is a suggestive fact in dealing with contagious maladies. I was in Natal in 1879, an d again for ten months in 1881 and 1882, and there saw very many cases of that terribly fatal disease called the South African Horse Sickness. It is a form of Anthrax, and is different from any disease we see, except on very rare occasions, in this country. In many cases of it horses go out of the stable to work apparently quite well, are in a very short time suddenly taken ill on the road or plain, begin to breathe rapidly, froth at the nose, and sometimes within half an hour are dead. It is a disease generally of low-lying ground, and is mala¬ rious in its origin. We now know that malarious diseases depend onlivingorganismSjOrbacteria. Like many other diseases of whicfy the Germ Theory is supposed to be an explanation, one attack confers immunity, and an animal which has survived the Horse Sickness is said to be “salted,” and therefore worth a con¬ siderably enhanced price when offered for sale. There are many curious facts connected with this disease, “ Horse Sick¬ ness,” about which you will find rather an exhaustive paper of mine in the VETERINARY JOURNAL for February, 1882. Not long ago Dr. Koch announced his investigations into the nature of the Tubercle Bacillus, which he has isolated and cul¬ tivated, and which he maintains is the cause of Tuberculosis , or, as it is commonly called, Consumption. It is calculated that tuberculous disease causes one-seventh of the deaths of the human race. It is, as you know, a common enough disease in cattle, and M. Koch’s discoveries in connection with the Tubercle Bacillus have led very many pathologists to consider the malady a transmissible or infectious one ; in fact, it must be stated that 17 opinion is decidedly tending in that direction. It is thought probable that not only may it be transmitted amongst people living together, but that also it may be communicated to mankind by the consumption of the milk and flesh of tuber¬ culous cattle. Whether Tuberculosis is infectious or not in the British Islands is still a much-disputed point in the medical profession. It is regarded as infectious in Spain, Italy, and other parts of Southern Europe, and great precautions with regard to disinfection are there taken after a fatal case. The weight of evidence of our highest medical authorities on the subject appears to show that they are at present inclined to think, that only in rare and exceptional cases is it infectious within the limits of the United Kingdom. It is demonstrated that Tubercle can be given by inoculation from man to the lower animals, and from these again to each other. Dr. Kammerer, the City Physician of Vienna, has recently reported that Tuberculosis is in very many instances communicated to mankind by the flesh and milk of tuberculous cattle, and he states that he regards the infection by this channel as being quite as fruitful a source amongst the young as the heredity to which it is usually ascribed. Professor Toussaint, who has devoted much time and attention to the question, thinks it very probable that if children, and even adults, were inoculated with Tuberculosis, very few would escape infection. He says that Tuberculosis of mankind is exactly the same as that of the ox or cow. Of this he has convinced him¬ self, by administering to animals human tuberculous matter, and by inoculating them with blood from tuberculous human subjects. Like the Tuberculosis of the cow, that of man is, he continues, inoculable through the digestive canal, and by blood and secretion fluids ; and it always presents identical characters.. He further states that true Tuberculosis, no matter whether derived from man, the cow, pig, or rabbit, can be reproduced in an infinite series with absolutely identical characters; and passes from animal to animal without being impaired in virulency; nay, more, it becomes all the more energetic and rapid in its action, the more frequently it is inoculated. (“ The Contagiousness of Tuberculosis.” By Professor Toussaint, Toulouse Veterinary School; in the Veterinary Journal, June, 1882.) From these- opinions from such high authority it will be seen how great a subject for investigation Tuberculosis is, and how interesting it is to us as veterinarians, not only as a disease of cattle, but also as a question to be attentively considered in relation to our meat and milk supply. Foot-and-mouth Disease , or the Vesicular Epizootic, is a very contagious disease, and may well be mentioned this evening, as it is now at work in England and Ireland. Besides affecting cattle and sheep, it sometimes attacks pigs, goats, horses, and other domesticated animals, as well as human beings. All kinds of causes have been named as producing Foot-and-mouth Disease, such as changes of weather, bad sanitary conditions,, overcrowding, fatigue, bad food, etc. It is, however, almost needless to tell you that it is becoming the general opinion, as it is the opinion of the most careful observers of disease, that it can only be caused by contagion or infection, and that it cannot be spontaneously generated. On the question of the spontaneous generation of diseases I shall have a few words to say before we conclude. We have every reason to believe that specific living organisms or germs are the cause of Foot-and-mouth Disease. The virus is supposed to be very tenacious of life, and to remain active for some weeks. Anything may retain and carry it—forage,, straw, hay, clothes, etc. A striking case is related in Mr. George Fleming’s valuable work, “ Sanitary Science and Police,” in which it is stated that troughs which had been lying for four months exposed in the fields, but which had before been used by diseased animals, gave Foot-and-mouth Disease. Another instance is given in the same work. A farmer owned two farms in an out-of-the-way place, and some distance from each other. On one farm Foot-and-mouth Disease had prevailed severely the other farm was free from it. The disease disappeared from the infected farm, and nothing more was seen of it for five months, when one of the hay-racks was brought to the healthy one, and very soon the cattle which fed out of it sickened. There was no traffic in the locality, nor yet disease, until the tainted rack was carried down. 19 The infection of Foot-and-mouth Disease is probably carried in the air for a short distance. Some practitioners deny this; but it is good policy and very desirable to act as if we were sure of it. It is, doubtless, conveyed in straw, hay, men’s f clothes, railway trucks, etc., and is also communicated by using contaminated troughs or other feeding and drinking vessels. It has often been unconsciously carried by men who have been « in contact with diseased animals. Foot-and-mouth Disease was introduced into Australia in 1872 by a cargo of diseased cattle from England, but was, fortunately, detected in time, and at once stamped out. One attack of Foot-and-mouth Disease does not confer im¬ munity, for the same animal may have it several times. It is, however, believed by the majority of observers that animals are only attacked once in a season, but some cattle will take it at intervals of only a few months. Inoculation is practised in some places for Foot-and-mouth -*> Disease—not protective inoculation, but inoculation in order to give the disease to all the animals on a farm or in a herd at once, and so have quickly done with it. Impressed with some¬ thing like this idea, some stockowners in this country say that it would, in the present outbreak, be better to allow the disease to spread, and so let all the cattle get rapidly over it. I need hardly tell you that the objections to such a course are many and grave, and such as could not be entertained by any respon¬ sible authority. Pleuro-pneumonia Contagiosa .—The contagious Pleuro-pneu- monia of cattle is, as you know, a specific constitutional disease, 4 chiefly manifesting itself in the lungs and pleura, and a very dreadful scourge it is. When we look at it by the light of the germ theory, we at once conclude that] it depends on the * presence in the sick animal’s body of a specific living organism, or microbe, as, indeed, its whole course plainly indicates. We are consequently not surprised to learn that the bacterium has been discovered at the University of Louvain, in Belgium, by MM. Bemylants and Verriest. The bacterium exists in the form of micrococcus. As you all know, protective inoculation against this disease has 20 long been practised on the Continent and other parts of the world, but in the United Kingdom it has made comparatively little way, or only too often it has been tried to be condemned. It must be confessed that the failures have been mostly due to erroneous methods of procedure. Of late years, however, Mr. R. Ruther¬ ford, a talented Edinburgh veterinary surgeon, has extensively and most successfully practised the operation, and has shown how to perform it. He has fully explained all matters of detail, and how to avoid the mistakes and accidents whicii caused former failures. “ He has,” says Professor Williams in his last edition of “The Principles of Veterinary Medicine,” “proved that inoculation will at once and most effectively arrest the spread of Pleuro-pneumonia amongst horned cattle.” I was in Edinburgh in 1880, and from conversations with the keen-witted and practical dairymen I ascertained that they considered the operation a genuine success. You can see the modus operandi described at length by Mr. Rutherford in the VETERINARY Journal for July, 1882. I should state that some experimentalists in preventive ino¬ culation for Pleuro-pneumonia have recommended the injection of the lymph into the blood-vessels of the ear. Now this, as Mr. Rutherford has pointed out, is a most objectionable and unsuitable place, for if untoward complications arise, as they sometimes do, the important structures in and about the head are at once involved, and a fatal result is almost unavoidable. Mr. Rutherford therefore chooses the tip of the tail for the operation, it being the furthest removed from important organs, and, conse¬ quently, the safest place, besides being quite as effectual as any other situation. Of course, he employs lymph taken from a lung affected with Pleuro-pneumonia, and without any cultiva¬ tion, or so-called “ attenuation,” and therefore the method here is quite different from that of M. Pasteur for Splenic Fever. It is very remarkable that protective inoculation for Pleuro¬ pneumonia has not been more practised in this country. Glanders and Farcy are manifestations of each other. They rarely occur in the army, because as soon as they are detected they are rigorously stamped out, and all precautionary measures are taken. In a recent number of the Archives Veterinaires is a joint paper by MM. Bouchard, Capitan, and Charran, giving the results of researches from November, 1881, to the end of December, 1882, into the nature of Glanders. You will see a translation of this paper in the VETERINARY JOURNAL for the month of April, 1883. They have discovered that Glanders depends on a rod-shaped bacillus, very like the Tubercle bacillus of Koch, whicfi a reference to the diagram will show you is a very small one, especially if compared with the bacillus of Splenic Fever ( Bacillus Anthracis) , which you will see is a very large one. Their researches and cultivations of this Glanders bacillus were very elaborate. Shortly to state the principal facts of their report, I may say that horses, asses, cats, and guinea-pigs were inoculated with the cultivated fluid, and readily took the malady, showing after death the usual diseased lung signs, the miliary tubercles, nasal ulcerations, and tumefied glands. Some of the cultivations were made from the pus of an abscess of a man suffering from Farcy, and these being used on guinea-pigs and a donkey produced Glanders. It is unneces¬ sary to give details of their experiments, but the result is they conclude that they have demonstrated the parasitic nature of Glanders and Farcy. The most advanced pathologists now believe that Glanders and Farcy cannot be spontaneously generated, no matter how bad the sanitary conditions may be to which horses are exposed. Veterinary practitioners are becoming gradually converted to this opinion, which has long been entertained in some other parts of Europe. It is believed that Glanders and Farcy arise only from contagion or infection, and that they cannot be originated, either by debilitating diseases or bad sanitary con¬ ditions. Such bad circumstances undoubtedly render animals far more liable to contract disease, by weakening their powers of resistance, and therefore make them fit subjects for the reception of any contagion ; this may be said to be a general pathological law. We must also remark that bad sanitary conditions make houses, stables, and other buildings and places, much more suit¬ able for the propagation and preservation of disease germs , therefore cleanliness, and good ventilation, and drainage cannot be too much recommended and enforced. 22 It is, as we have already observed, becoming more and more the belief that before animals contract Glanders they must have in some way received the contagium of a previous case. The same remark of course applies to Farcy, it being only a modifica¬ tion of Glanders. The contagious matter of Glanders may be carried about by dogs, cats, goats, etc., and by grooms and other persons about their hands and clothes, and of course by articles used about in¬ fected animals. The dried matter may be carried about in a stable by the air, and horses may sniff its contained germs into the nostrils. It is instructive to note that Glanders has not yet appeared in Australia and New Zealand, although horses there, as here, are exposed to every kind of hardship and bad sanitary conditions. Now mark what follows. Horses in large numbers are exported from Australia to the East Indies (Hindostan), and when they get there and are exposed to the contagion, they readily con¬ tract Glanders. The inference therefore is that the germs on which the disease depends have not yet found their way to Australia and New Zealand, but that if they did so horses in those countries would be as likely to suffer as in other parts of the world. I have in two different voyages to Natal, of exactly forty days each, seen a very large number of horses, over two hundred and seventy in the one case, and two hundred and thirty-seven in the other, cooped up on board ship—that is for six weeks all but two days in each voyage, and a good part of this time was in the tropics, where all the circumstances of stifling heat, etc., would have led us to expect an outbreak of Glanders, but none occurred. Here, again, the inference is that there were no pre¬ viously infected animals on board; in fact, a very rigorous veteri¬ nary examination to assure ourselves of the healthy condition of the horses was made before they left barracks for the port of embarkation. It may be here stated that Professor Galtier, of the Lyons Veterinary School, has inoculated dogs with Glanders matter. The dogs recover from such inoculation, but the virus passed through their systems is weakened. By this, some considerations as to the possibility of protective inoculation are suggested. M. Galtier advises the inoculation test for Glanders to be made on the dog instead of on the ass. With respect to the impolicy of allowing that Glanders or Farcy, or any contagious or infectious disease, can be spontane¬ ously generated, I shall make some further remarks before we conclude. Rabies and Hydrophobia are believed to owe their existence to Germs, and if this be so we are entitled to assume that they cannot be spontaneously generated. The best authorities are gradually coming round to this view. As you know, Mr. George Fleming is our greatest authority on Rabies and Hydrophobia. He now believes that it is a purely contagious disorder, or in other words, that it does not arise spontaneously—an opinion which has long been held by many Continental observers. In support of this view I may state, that in some countries Rabies has never appeared. In the Island of Mauritius, where the impor¬ tation of dogs is permitted by our Government it exists, but in the neighbouring Island of Reunion, which belongs to France, and where importation of dogs is forbidden, it has never been seen. Australia and New Zealand are also free from it. It is well known that some individuals will resist some con¬ tagious diseases. There was a dog at the great veterinary school of Alfort, which could not by repeated inoculations be made to take Rabies. This immunity of individuals from some contagious maladies has often misled investigators who are content to base their conclusions on the result of one or very few experiments, and shows us that we should not hastily arrive at a decision. M. Galtier, in a paper presented to the French Academy of Sciences on the 1st August, 1881, proposes as a method of protective inoculation for Rabies to inject the virus of the disease into the circulatory current of healthy animals. He has performed some successful experiments in this direction, but further investigation is desirable. As to the tissues of the body which contain the virus of Rabies, it may here be mentioned that M. Pasteur and MM. Chamberland, Roux, and Thuillier, his assistants, in a joint 24 paper read before the French Academy of Sciences on May 30th, 1881, stated that they had communicated the disease by inoculating with portions of the brain and medulla oblongata. Rabies is quickly thus produced—in a week or a fortnight—and therefore for experimental purposes saves the trouble and delay of waiting for the long incubatory period, which frequently follows the bite of a rabid animal. M. Pasteur also states that the incubatory period of Rabies can be much shortened by inoculating direct into the brain, and this would make it appear that the virus has quickly reached its favourite locality, without having to go through various tissues, during which time it is inactive. We know that Rabies chiefly affects the brain and adjacent parts. It should be added that M. Pasteur is paying much attention to Rabies, and has recently announced some results ; but as a controversy on the subject is now going on between him and M. Koch, it is needless to further mention them to-night. This concludes our brief notice of a few of the most important transmissible maladies in which the veterinary practitioners of the United Kingdom are interested, but we cannot finish a paper on the Germ Theory without shortly noticing the doctrine of Spontaneous Generation. If, as we have endeavoured to show, every infectious and transmissible disease depends on its own particular living organism, it is difficult to conceive the spontaneous generation of such diseases. “ That a virus producing the peculiar symptoms of Small-pox or Scarlet Fever—symptoms so much alike in each case, in innumerable instances, and for so many centuries ”— should be spontaneously generated would be wonderful. That diseases occur where no previous case could have been is a truism, but contagion and infection are conveyed, as we every day see, in such remarkable and mysterious ways, that he is a bold man who accepts negative proof of spontaneous generation in the face of so many and constantly-recurring instances, where the malady is evidently due to contagion. On this subject Dr. Charles Cameron says: “ No one who has read the recent work of Professor Tyndall can doubt that the doctrine of spontaneous generation is dead.” 25 A favourite argument of the advocates of the spontaneous generation of disease is to ask how we account for the first case. Might we not just as well be asked how we account for the first oak tree ? Yet if we found one growing on a newly-discovered and ^ far-away solitary island, we should not dream of attributing it to spontaneous generation—we should feel certain that the seed of • a former oak tree had, by some means or other, reached the « island. In reply to such questions we may quote what Dr. William Aitken (“Outlines of Science and Practice of Medi¬ cine ”), speaking of specific diseases, says: “ The origin of all of them, so far as 4 how their respective first contagia arose/ is alike unknown, just as in physiology the exact ‘ origin of species ’ is unknown, Indeed, these speculations may be only two phases of one question.” But it is not good policy on our part as veterinary surgeons to admit the spontaneous generation of contagious and infectious diseases. If we do so we make people careless about preventing contagion, and we allow excuses for neglect of precautionary measures. Some able observers think that if we say contagious and infectious diseases cannot arise spontaneously, we afford an excuse for the idle, the dirty, and the ignorant for their neglect of sanitary measures; but when we know, as we have just pointed out in speaking of Glanders, that bad sanitary arrange¬ ments not only weaken subjects, but render them a comparatively easy prey to disease, besides giving suitable conditions for the preservation and propagation of disease germs, we have therein the strongest arguments for enforcing cleanliness, good drainage, and proper ventilation. We cannot too much insist upon these ^ essential requisites for good health. When we sometimes hear of mysterious outbreaks of some * malady, for instance, Foot-and-mouth Disease, in places where + no access of possibly infected animals has been allowed, we may be puzzled and the advocates of spontaneous generation may be triumphant. If, however, we remember, that human beings, horses, dogs, vermin, running game, and other animals can, and sometimes do, convey the virus, we should be very rash if we declared outbreaks to be spontaneously generated because we could not trace the channel of contagion. 26 The foregoing remarks appear to prove, that to admit the doctrine of the spontaneous generation of contagious and infec¬ tious diseases is to disregard the latest teachings of science and research. If we recognise this doctrine we make people, as before said, careless, reckless, and despairing about preventing and stamping out such scourges, for they will then argue that precautions are of little or no use, as disease may and will originate in spite of them. Let us avoid and discourage such impolitic and erroneous views, and consistently refuse to allow that contagious and infectious diseases can be spontaneously generated. FINIS. n * HAZELL, WATSON, AND VINEY, PRINTERS, LONDON AND AYLESBURY.