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Originally appearing in Volume V28, Page 160 of the 1911 Encyclopedia Britannica.
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VIVISECTION, literally the cutting (sectio) of living (vivus) animals, a word which might be applied to all surgical operations whether practised upon the lower animals or on man. As conventionally used, however, it has exclusive reference to experiments upon the lower animals undertaken for the advancement of medical sciences. There are a number of people who, calling themselves anti-vivisectionists, strongly object to these experiments on the lower animals; and it must be conceded that the humane reasons which they advance against it can only be set aside as " sentimental " if considerations of a wider humanity can show that the arguments of the anti-vivisectionists really run counter to human progress. The supporters of vivisection, properly considered, must not be confused with those who would make a barbarous use of this means of research. What is at stake here is the right to use it properly and at all. It would be possible for cruelty of an unnecessary kind to result if the practice of vivisection were unrestricted; and the purpose of this article is to give some account of the method of experiments on animals as sanctioned by law in the United Kingdom, and to justify that method by setting forth the chief historical discoveries that have been made by the help of vivisection. Such experiments have for their object the advancement of the sciences of physiology and pathology. From the earliest periods experimental vivisections have occasionally been practised, but before the days of anaesthetics it was difficult to execute them,•and not less difficult to draw conclusions. The invention of anaesthetics has greatly extended the scope of the experimental method, because an animal can be kept unconscious and quiet, without even a quiver of a•muscle, during prolonged operations. Further, the introduction of the antiseptic method has made it possible to subject all tissues and regions of the body to surgical interference, and this has also had the effect of increasing the possibilities of experimental research. In 1906 a British Royal Commission was appointed to inquire into the whole subject under the chairmanship of Lord Selby, on whose death Mr A. J. Ram, K.C., took the chair. The Commission sat from October 1906 to March 1908, and heard no fewer than 21,761 questions and answers. In view of attempts on the part of the anti-vivisectionists to misrepresent the nature of the evidence given before the Commission, in January 1908 the supporters of experiments on animals founded the Research Defence Society, under the presidency of Lord Cromer; by July 1910 this society had some 3500 members. Its official address is 21 Ladbroke Square, London, W. I. METHODS EMPLOYED. :The present act relating to experiments on animals was passed in 1876. At that time the majority of these experiments were physiological. There was, it may be fairly said, no such thing as bacteriology, no general following up of Pasteur's work. A few experiments were made in pathology, for instance in tubercle; and a few in surgery, in pharmacology, and in the action of poisons, especially snake venom. But the chief use of experiments on animals was for the advancement of physiology. The evidence given before the Royal Commission (1875) was almost entirely on physiological matters, on the discoveries of Harvey, Bell, Magendie and Claude Bernard, on the Handbook f or the Physiological Laboratory, and so forth. The act, therefore, was drafted with a view to physiology, without much concern for pathology, and without foreknowledge of bacteriology. At the time of writing (191o), 95% of the experiments are inoculations. Every experiment must be made in a registered place open to government inspection. But inoculation experiments are sometimes permitted in non-registered places, for the immediate study of outbreaks of disease, or in circumstances which render it impracticable to use a registered place. Every experiment must be made under a licence; and every application for a licence must be recommended by the signatures of two out of a small body of authorities specified in the act—presidents of certain learned societies and professors of certain universities and colleges. The word " experiment " is not allowed to cover the use of more than one animal. Most experiments are made not under a licence alone, but under a licence plus one or more certificates, and the wording and working of these certificates must be clearly understood, because it is over them that the question arises as to the amount of pain inflicted by these experiments. Under the licence alone, the animal must be kept under an anaesthetic during the whole of the experiment; and " if the pain is likely to continue after the effect of the anaesthetic has ceased, or if any serious injury has been inflicted on the animal," it must be killed forthwith under the anaesthetic. Thus, under the licence alone, it is impossible to make an inoculation; for the experiment consists, not in the introduction of the needle under the skin, but in the observation of the results of the inoculation. A guinea-pig inoculated with tubercle cannot be kept under an anaesthetic till the disease appears. The disease is the experiment, and it is therefore an experiment made without an anaesthetic, and not authorized by the licence alone. Again, under the licence alone it would have been impossible to work out the thyroid treatment of myxoedema, or the facts of cerebral localization. For to remove the thyroid gland, or to remove a portion of the surface of the brain, is to inflict a serious injury on the animal. The operation is done under profound anaesthesia—it would be impracticable otherwise; the wound is treated and dressed by the antiseptic method—suppuration would invalidate the result. But a serious injury has been inflicted. Nevertheless, the animal must not be killed forthwith: the result must be watched. These and the like experiments cannot therefore be made under the licence alone. For the removal of such disabilities as these, the act empowers the home secretary to allow certain certificates, to be held with the licence. They must be recommended by two signatures, and various restrictions are put upon them by the home secretary. On July s1, 1898, the home secretary was asked, in the House of Commons, what were the conditions and regulations attached by the Home Office to licences and certificates; and he answered " The conditions are not always the same, but may vary according to the nature of the investigation. It is hardly possible, therefore, for me to state all the conditions attached to licences and certificates. The most important conditions, however (besides the limitations as to place, time and number of experiments), and the conditions most frequently imposed, are those as to reporting and the use of antiseptics. The latter condition is that the animals are to be treated with strict antiseptic precautions, and if these fail and pain results, they are to be killed Immediately under anaesthetics. The reporting conditions are, in brief, that a written record, in a pre-scribed form, is to be kept of every experiment, and is to be open for examination by the inspector; that a report of all experiments is to be forwarded to the inspector; and that any published account of an experiment is to be transmitted to the secretary of state. Another condition requires the immediate destruction under anaesthetics of an animal in which severe pain has been induced, after the main result of the experiment has been attained." The home secretary attaches to licences and certificates such endorsements as he thinks fit. The bare text of the act, now thirty-four years old, is a very different thing from the administration of the act; and the present writer is in a position to say that the act is administered with great strictness, under a careful system of inquiry and reference. The certificates are distinguished as A, B, C, E, EE and F. Certificate D, which permitted the testing, by experiments, of " former discoveries alleged to have been made," has fallen into disuse. Certificate C permits experiments to be made by way of illustration of lectures. They must be made under the provisions contained in the act as to the use of anaesthetics. Certificates E and EE permit experiments on dogs or cats; certificate F permits experiments on horses, asses or mules. These certificates are linked with Certificate A or Certificate B. It is round these two certificates, A and B, that the controversy as to the pain caused by experiments on animals is maintained. Certificate A permits experiments to be made without anaesthesia. It is worded as follows: " Whereas A. B. of [here insert address and profession] has represented to us (i.e. two authorities) that he proposes, if duly authorized under the above-mentioned act, to perform on living animals certain experiments described below: We hereby certify that, in our opinion, insensibility in the animal on which any such experiment may be performed cannot be produced by anaesthetics without necessarily frustrating the object of such experiment." All inoculations under the skin, all feeding experiments and the like, are scheduled under this certificate. They must be scheduled somehow: they cannot legally be made under a licence alone. Though the only instrument used is a hypodermic needle, yet every inoculation is officially returned as an experiment, calculated to give pain, performed without an anaesthetic. It is for inoculations and the like experiments, and for them alone, and for nothing else, that Certificate A is allowed (or A linked with E or F). This want of a special certificate for inoculations, and this wresting of Certificate A for the purpose, have led to an erroneous belief that " cutting operations' are permitted by the act without an anaesthetic. But, as the home secretary said in parliament, in March 1897, " Certificate A is never allowed except for inoculations and similar trivial operations, and in every case a condition is attached to prevent unnecessary pain." And again he wrote in 1898, Such special certificates (dispensing with anaesthetics) are granted only for inoculations, feeding and similar procedures involving no cutting. The animal has to be killed under anaesthetics if it be in pain, so soon as the result of the experiment is ascertained." Certificate B permits the keeping alive of the animal after the initial operation of an experiment. It is worded as follows: " Whereas A. B. of [here insert address and profession] has represented to us (i.e. two authorities) that he proposes, if duly authorized under the above-mentioned act, to perform on living animals certain experiments described below, such animals being, during the whoie of the initial operation of such experiments, under the influence of some anaesthetic of sufficient power to prevent their feeling pain: We hereby certify that, in our opinion, the killing of the animal on which any such experiment is performed before it recovers from the influence of the anaesthetic administered to it would necessarily frustrate the object of such experiment." Certificate B (or B linked with EE or F) is used. for those experiments which consist in an operation plus subsequent observation of .the animal. The section of a nerve, the removal of a secretory organ, the establishment of a fistula, the plastic surgery of the intestine, the sub-dural method of inoculation—these and the like experiments are made under this certificate. We may take, to illustrate the use of Certificate B, Horsley's observations on the thyroid gland. The removal of the gland was the initial operation; and this was performed under an anaesthetic, and with the antiseptic method. Then the animal was kept under observation: The experiment is neither the operation alone nor the observation alone, but the two together. The purpose of this certificate is set forth in the inspector's report for 1909. " In the experiments performed under Certificate B, or B linked with EE, 1704 in number, the initial operations are performed under anaesthetics from the influence of which the animals are allowed to recover. The operations are required to be performed antiseptically, so, that the healing of the wounds shall, as far as possible, take place without pain. If the antiseptic precautions fail, and suppuration occurs, the animal is required to be killed. It is generally essential for the success of these experiments that the wounds should heal cleanly, and the surrounding parts remain in a healthy condition. After the healing of the wounds the animals are not necessarily, or even generally, in pain, since experiments involving the removal of important organs, including portions of the brain, may be performed without giving rise to pain after the recovery from the operation; and after the section of a part of the nervous system, the resulting degenerative changes are painless. In the event of a subsequent operation being necessary in an experiment performed under Certificate B, or B linked with EE, a condition is attached to the licence requiring all operative procedures to be carried out under anaesthetics of sufficient power to prevent the animal feeling pain; and no observations or stimulations of a character to cause pain are allowed to be made without the animals being anaesthetized. In no case has a cutting operation more severe than a superficial venesection (the opening of a vein just under the skin) been allowed to be performed without anaesthetics." From this brief account of the chief provisions of the act, we come to consider the general method of experiments on animals in the United Kingdom, and the question of the infliction of pain on them. The figures for a representative year may be given. The total number of licensees in 19o9r in England and Scotland, was 483: of whom 135 performed no experiments during the year. The total number of experiments was 86,277, being 2357 less than in 1908. They were made as follows : Under Licence alone . Certificate C . Certificate A . Certificates A+E Certificates A+F Certificate B Certificates B +EE Certificate F . . The experiments performed under Certificate A (or A+E, or A+F) were mostly inoculations; but a few were feeding experiments, or the administration of various substances by the mouth or by inhalation, or the abstraction of blood by puncture or by simple venesection. Inoculations into deep parts, involving a preliminary incision, are required to be per-formed under anaesthetics (Certificate B). " It will be seen," says the report for 1909, " that the operative procedures in experiments performed under Certificate A, without anaesthetics, are only such as are attended by no considerable, if appreciable, pain. The certificate is, in fact, not required to cover these proceedings, but to allow of the subsequent course of the experiment. The animals most used for inoculations are mice, rats, guinea-pigs and rabbits. It is not once in a thousand times that a dog or a cat is used for inoculation. The act of inoculation is not in itself painful. A small area of the skin is carefully shaved and cleansed, that it may be aseptic, the hypodermic needle is sterilized and the method of hypodermic injection or of vaccination is the same as it is in medical practice. "A guinea-pig that will rest quietly in your hands before you commence to inject it, will remain perfectly quiet during the introduction of the needle under the skin; and the moment it is returned to the cage it resumes its interrupted feeding. Arteries, veins and most of the parts of the viscera are without the sense of touch. We have actual proof of this in what takes place when a horse is bled for the purpose of obtaining curative serum. With a sharp lance a cut may be, made in the skin so quickly and easily that the animal does nothing more than twitch the skin-muscle of the neck, or give his head a shake, while of the further proceeding of introducing a hollow needle into the vein, the animal takes not the slightest notice. Some horses, indeed, will stand perfectly quiet during the whole operation, munching a carrot, nibbling at a wisp of hay, or playing with a button on the vest of the groom standing at its head." These sentences, written in the Medical Magazine (June 1898) by Dr Sims Woodhead, Professor of Pathology at Cambridge, are sufficient evidence that inoculations and the like experiments are not painful at the time. In a few instances cultures of micro-organisms have been made in the anterior chamber, of the eye, by the introduction of a needle behind the cornea. This might be thought painful, but cocaine renders the surface of the eye wholly insensitive. Many operations of opfithalmic surgery are done under cocaine alone, and the anterior chamber of the eye is so far insensitive that a man may have blood or pus (hypopyon) in it, and hardly be conscious of the fact. The results of inoculation are in some cases negative, in others positive; the positive results are, in the great majority of cases, not a local change, but a general infection which may end in recovery, or in death. The diseases thus induced may, in many cases, fairly be called painless—such are septicaemia in a mouse, snake-venom in a rat, and malaria in a sparrow. Rabbits affected with rabies do not suffer in the same way as dogs and some other animals, but become subject to a painless kind of paralysis. It is probable that animals kept for inoculation have, on the whole, less pain than falls to the lot of a like number of animals in a state of nature or in subjection to work: they are well fed and sheltered, and escape the rapacity of larger animals, the inevitable cruelties of sport, and the drudgery and sexual mutilation that man inflicts on the higher domestic animals. The present writer has, of course, seen the mice that are used for the study of cancer (Imperial Cancer Research Fund), and the guinea-pigs that are used at the Lister Institute for thetesting of the London milk-supply, lest the milk should convey tubercle. He did not see, among all the many animals, one that appeared to be suffering: save that a very few of the mice were incommoded, or, if the word be applicable to mice, distressed, by large tumours. Of the guinea-pigs that had been inoculated, not one seemed to be in any pain. A nodule of tubercle, or a tuberculous gland, is painless in us, and therefore cannot be painful in a guinea-pig. It is not denied that the study of some diseases (plague, tetanus) causes some pain to rats and rabbits; but this pain is hardly to be compared with the pain and horror of these diseases in man. We come now to Certificate B. If it were lawful, under Certificate B, to make an incision under an anaesthetic, to call this the " initial operation," and then, without an anaesthetic, to make painful experiments, through the incision, on the deeper structures, doubtless much pain might be inflicted under this certificate. But experiments of this kind can be, and are, made under the licence alone, the animal being kept under an anaesthetic all the time, and killed under it. " No experiments requiring anything of the nature of a surgical operation, or that would cause the infliction of an appreciable amount of pain, are allowed to be performed without an anaesthetic" (Inspector's Report for 1899). " These certificates (B) are granted on condition that antiseptic precautions are used; and if these fail, and pain continues after the anaesthetics have ceased to operate, the animal is immediately killed painlessly" (Letter from the Home Secretary, 1898). Of experiments made under this certificate (which must be linked with Certificate EE for any experiment on a dog or a cat), three instances may be given here: an operation on the brain, a removal of part or the whole of a secreting gland, and the establishment of a fistula. It is to be noted that, for these and the like operations, profound anaesthesia and the strict observance of the antiseptic method are matters of absolute necessity for the success of the experiment: the operation could not be performed without anaesthesia; and the experiment would come to nothing if the wound suppurated. It is to be noted, also, that these operations are such as are performed in surgery for the saving of life or for the relief of pain. As to operations on the brain, it must be remembered that the surface of the brain is not sensitive. Therefore the removal or destruction, of a portion of the surface of the brain, or the division of some tract of central nervous tissue, though it might entail some loss of power or of control, does not, cause pain: a wound of the brain is painless. Tension within the ;cranial cavity, as in cases of cerebral tumour or cerebral abscess, may indeed cause great pain; and, if the aseptic method failed, in an experiment, inflammation and tension would ensue: in that case the animal must be killed. The removal of part or the whole of a secreting gland (e.g. the thyroid, the spleen, the kidney) is performed by the same methods, and with the same precautions, as in human surgery. Profound anaesthesia, and the use of a strict antiseptic procedure, are of absolute necessity. The skin over the part to be removed must be shaved and carefully cleansed for the operation; the instruments, sponges and ligatures must be sterile, not capable of infecting the wound; and when the operation is over, the wound must be carefully closed with sutures, and left to heal under a proper surgical dressing. The establishment of a fistula, again, is an operation practised, as a matter of course, in large numbers of surgical cases. The stomach, the gall-bladder, the large intestine, are opened for the relief of obstruction, and kept open, either for a time or permanently, according to the nature of the case. Under anaesthesia, the organ that is to be opened is exposed through an incision made through the structures overlying it, and is secured in the wound by means of fine sutures. Then, when it has become adherent there, it is opened by an incision made into it; no anaesthetic is needed for this purpose, because' these internal organs are so unlike the skin in sensitiveness that an incision is hardly felt : the patient may say that he " felt a -prick," or he may be wholly unconscious that anything has been done. A 1,980 196 81,566 595 1,385 319 8 fistula thus established is not afterward painful, though there may be some discomfort now and again. The classical instance is the case of Alexis St Martin, who was shot in the stomach in 1822, and recovered, but with a fistula. He let Dr Beaumont make experiments on him for nine years: " During the whole of these periods, from the spring of 1824 to the present time (1833), he has enjoyed general good health . . . active, athletic and vigorous; exercising, eating and drinking like other healthy and active people. For the last four months he has been unusually plethoric and robust, though constantly subjected to a continuous series of experiments on the interior of the stomach; allowing to be introduced or taken out at the aperture different kinds of food, drinks, elastic catheters, thermometer tubes, gastric juice. chyme, &c., almost daily, and sometimes hourly. Such have been this man's condition and circumstances for several years past; and he now enjoys the most perfect health and constitutional soundness, with every function of the system in full force and vigour " (Beaumont, Experiments and Observations on the Gastric Juice, 1838). We come now to the question, What anaesthetics are used in these experiments, and are they properly administered? The anaesthetics used are—(r) chloroform, ether, or a mixture containing chloroform and ether; (2) morphia, chloral, urethane. It is sometimes said that morphia is not an anaesthetic. That depends on the quantity given. Not a month passes in this country without somebody killing himself or herself with morphia or chloral. They die profoundly anaesthetized: they cannot,be roused; even the pain of a strong electric shock is not enough to rouse them. So it is with animals. The doses given to them are enormous and produce complete insensibility. On this point the evidence given before the Royal Commission of 1906-8 by Mr Thane, Professor Schafer, Sir Lauder Brunton, Sir Henry Morris, Professor Dixon, Dr Dudley Buxton and Professor Starling is absolutely conclusive. " As to the statements," says Sir Lauder Brunton, " that chloral and opium or morphia are not narcotics, and do not remove pain, there is no other word for it, it is simply a lie; you may as well say that chloroform does not remove pain. If you give any animal a sufficiently large dose of chloral or opium, you so completely abolish sensibility that there is nothing you can do that will awaken its sensibility. The animal is as senseless as a piece of board." With regard to chloroform, ether and the A.C.E. mixture (alcohol, chloroform and ether) it is absolutely certain that animals can be kept, with these anaesthetics, profoundly unconscious for three or four or more hours. Nothing on this point is more worthy of consideration than the evidence in veterinary surgery, given before the Royal Commission by Mr Hobday, one of the very foremost veterinary surgeons in this country (Reports of Evidence, vol. iv. Q. 16284-16523). The opponents of all experiments on animals are apt to believe that dogs and cats must be bound and fastened on boards, and then have the anaesthetic given to them. That is not the case. They can take the anaesthetic first, and then be put in position; just as we, for many of the operations of surgery, are bound in position. And, of course, dogs and cats cannot lie on their backs as we can. " The usual thing we do," said Professor Starling, in his evidence before the Royal Commission, " is to give the animal, half an hour before the experiment, a hypodermic injection of morphia, of about a quarter of a grain--from a quarter to a third. The effect of that is, that the dog becomes sleepy and stupid, and then sometimes it will lie down quietly, and if it is very sleepy you can put a mask over its nose containing the chloroform, alcohol and ether mixture, which it takes quite quietly. If, at the time one wants to begin the operation, the animal is not fully under the influence of morphia —if it still seems restless—it is put in a box, and there it has some wool saturated with the A.C.E. mixture put in the box. The air gradually gets saturated, the dog gets more and more sleepy, and finally subsides at the bottom of the box." A few words must be said here about curare. It was said, some years ago, by an opponent of experiments on animals, that " curare is used daily throughout England," whereas, it is seldom used at all, and is never used alone in any sort or kind of operation on any animal in this country: in every such case a recognized anaesthetic must be given, and is given. In large doses curare not only abolishes the movement of the voluntary muscles,. but also acts as an anaesthetic: in small doses it acts only on the voluntarymuscles, i.e. on the endings of the motor nerves going to these muscles. For example, suppose that the object of the experiment is to observe and record the action of a nerve on the contraction of certain blood vessels. The nerve gives off some branches to muscles, and other branches to blood vessels. If the animal be anaesthetized, and the nerve. stimulated, muscles and vessels will both contract; but, if curare be given, as well as an anaesthetic, the vessels alone will contract, without the muscles: for curare does not act on the endings of motor nerves going to blood vessels. But, as a practical matter, curare is very hard to obtain, and is often impure, and is very seldom used. One of the inspectors said to the Royal Commission that he had once seen it used, fifteen years ago. Professor Gotch said that he had not used it, in his own work, for twenty years. Professor Schafer said that he had not used it for years. And Sir Lauder Brunton said that he did not think he had used it at all since the passing of the act of 1876. The fear that, in a case where curare was being used, the effect of the anaesthetic might " pass off," and the animal be left under curare alone, is not reasonable. The dosage and administration of anaesthetics is not left to chance. If, for example, an animal is receiving a definite percentage of chloroform vapour, it is of necessity under the influence of the chloroform: and the anaesthesia will gradually become not less but more profound. (See the evidence given before the Royal Commission by Professor Langley and Professor Waller.) It may be interesting to compare the pain, or death, or discomfort among 86,277 animals used for experiments in Great Britain in 1909, with the pain, or death, or discomfort of an equal number of the same kinds of animals, either in a state of nature, or kept for sport, or used for the service of human profit or amusement. But it would be outside the purpose of this article to describe the cruelties which are inseparable from sport, and from the killing of animals for food, and from fashion; neither is this the place to describe the millions of mutilations which are practised on domestic animals by farmers and breeders. As one of the Royal Commissioners recently said, the farmyards, at certain times of the year, simply " seethe with vivisection." The number of animals wounded in sport, or in traps, cannot be guessed. Against this, vast amount of suffering we have to put an estimate of the condition of 86,277 animals used for medical science. Ninety-five per cent. of them were used for inoculation. In many of these inoculations the result was negative: the animal did not take any disease, and thus did not suffer any pain. In many more, e.g. cancer in mice, tubercle in guinea-pigs, the pain or discomfort, if any, may fairly be called trivial or inconsiderable. It could hardly be said that these small animals suffer much more than an equal number of the same kind of animals kept in little cages to amuse children. There remain 3888 animals which were submitted to operation under an anaesthetic . In the greater number of these cases the animal was killed then and there under the anaesthetic, without recovering consciousness. In the remaining cases the animal was allowed to recover, and to be kept for observation; but no further observation of any kind, which could cause pain, was allowed to be made on it, unless it were again placed under an anaesthetic. Many of these cases, thus allowed to recover after an operation, may fairly be compared to an equal number of domestic animals after one of the formal operations of veterinary surgery. These observations made under Certificate B form but a very small proportion of the total number of experiments on animals in the United Kingdom; and they have led, in recent years; to discoveries of the very utmost importance for human life and health. II. SCIENTIFIC RESULTS.—We come now to consider the results of experiments on animals, but we must remember that not we alone, but animals also, owe a great debt to them. Great epizootic diseases like anthrax, swine-fever, chicken cholera, silkworm disease, pleuro-pneumonia, glanders, Texas cattle fever, blackleg, tuberculosis in cattle, have killed yearly millions of animals, and have been brought under better control by these experiments. The advantages that have been obtained for man may be arranged under two heads—(A) :Physiology, (B) Pathology, Bacteriology and Therapeutics. A. PHYSIOLOGY 1. The Blood.—Galen (A.D. 131) confuted the doctrine of Erasistratus, that the arteries contained ,rv€Gµa, the breath of life, proving by experiment that they contain blood. " Ourselves, having tied the exposed arteries above and below, opened them, and showed that they were indeed full of blood." Realdus Columbus (1559), though he did not discover the general or " systematic " circulation of the blood, yet seems to have discovered, by experiment, the pulmonary circulation. " The blood is carried through the pulmonary artery to the lung, and there is attenuated; thence, mixed with air, it is carried through the pulmonary vein to the left side of the heart. Which thing no man hitherto has noted or left on record, though it is most worthy of the observance of all men.... And this is as true as truth itself; for if you will look not only in the dead body but also in the living animal, you will always find this pulmonary vein full of blood, which assuredly it would not be if it were designed only for air and vapours... . Verily I pray you, 0 candid reader, studious of authority, but more studious of truth, to make experiment on animals. You will find the pulmonary vein full of blood, not air or uligo, as these men call it, God help them." Harvey's treatise De Motu Cordis et Sanguinis in Animalibus was published at Frankfort in 1621. It begins thus: " When by many dissections of living animals, as they came to hand,—Cum multis vivorum dissectionibus, uti ad manum dabantur, —I first gave myself to observing how I might discover, with my own eyes, and not from books and the writings of other men, the use and purpose of the movement of the heart in animals, forthwith I found the matter hard indeed and full of difficulty; so that I began to think, with Frascatorius, that the movement of. the heart was known to God alone. . . . At last, having daily used greater disquisition and diligence, by frequent examination of many and various living animals—multa frequenter et varia animalia viva introspiciendo—I came to believe that I had succeeded, and had escaped and got out of this labyrinth, and therewith had discovered what I desired, the movement and use of the heart and the arteries. And from that time, not only to my friends but also in public in my anatomical lectures, after the manner of the Academy, I did not fear to set forth my opinion in this matter." Here, and again at the end of the Preface, and again in the eighth chapter of the De Motu, he puts his experiments in the very foreground of the argument. Take the headings of his first four chapters: 1. Causae, quibus ad scribendum auctor permotus fuerit. 2. Ex vivorum dissectione, qualis fit cordis motus. 3. Arteriarum motus qualis, ex vivorum dissectione. 4. Moms cordis et auricularum qualis, ex vivorum dissectione. He had, of course, help from other sources—from anatomy and from physics; but it is certain, from his own words, that he attributed his discovery, in a very great measure, to experiments on animals. Malpighi (1661), professor of medicine at Bologna, by examining with a microscope the lung and the mesentery of the live frog, made out the capillary vessels. He writes to Borelli, professor of mathematics at Pisa, that he has failed in every attempt to discover them by injecting fluids into the larger vessels, but has succeeded by examining the tissues with the microscope: " Such is the divarication of these little vessels coming off from the vein and the artery, that the order in which a vessel ramifies is no longer preserved, but it looks like a network woven from the offshoots of both vessels " (De Pulmonibus, 1661). Stephen Hales (1733), rector of Farringdon and minister of Teddington, and a Fellow of the Royal Society, made the first exact estimates of the blood pressure, the real force of the blood, by inserting one end of a vertical glass tube into the crural artery of a mare, and noting the rise of the blood in the tube (Statical Essays, containing Haemostaticks, &c., 1733). John Hunter, born 1738, made many observations on the nature and processes of the blood; and, above all, he discovered the facts of collateral circulation. These facts were fresh in his mind when he first ventured, in December 1785, to tie the femoral artery in " Hunter's canal " for the cure of aneurism in the popliteal space. The experiment that gave him his knowledge of the collateral circulation was made on one of the deer in Richmond Park: he tied its external carotid artery, to see what effect would be produced on the shedding of the antler. Some days later he found that the circulation had returned in the antler. He had the buck killed, and found that the artery had been completely closed by the ligature, but the small branches coining from it, between the heart and the ligature, were enlarged and were in communication with others of its branches beyond the ligature; and bye this Collateral circulation the flow of blood to the antler had en restored. Among later observations on the circulation must be mentioned the use of the mercurial manometer by Poiseuille (1828) and Ludwig (1849), the study of the blood pressure within the heart by Hering (1849) and the permanent tracing of the pressure curves by Chauveau and Marey (1863). Finally came the study of those more abstruse problems of the circulation that the older physiologists had left alone—the influences of the central nervous system, the relations between blood pressure and secretion, the automatism of the heart-beat, and the influence of gravitation. Professor Starling, in 1906, writes as follows of this part of physiology: " Among the researches of the last thirty years, those bearing on the circulation of the blood must take an important place, both for their physiological interest and for the weighty influence they have exerted on our knowledge and treatment of disorders of the vascular system, such as heart disease. We have learned to measure accurately the work done by the great heart-pump; and by studying the manner in which this work is affected by different conditions, we are enabled to in-crease or diminish it, according to the needs of the organ. Experiments in what is often regarded as the most transcendental department of physiology—i.e. that which treats of muscle and nerve—have thrown light on the wonderful process of ` compensation ' by which a diseased heart is able to keep up a normal circulation." And Dr James Mackenzie, writing in 1910 of certain irregularities of the circulation during pregnancy (venous pulse in the neck and irregular beat of the heart), says, very emphatically, that these conditions in patients have been interpreted by ex- Eeriments on animals. " The outcome of these researches [Wenckeach's clinical studies], as well as those of a great number of other observers, has been to elucidate the nature and meaning of a great number of abnormal conditions of the heart. It might be said with truth that, whereas a few years ago irregular action of the heart was one of the most obscure symptoms in clinical medicine, it is now one of the best understood. It is needless to repeat that this advance would have been absolutely impossible without the knowledge gained by experiment " (Research Defence Society, May 1910). 2. The Lacteals.—Asellius (1622) by a single experiment demonstrated the flow of chyle along the lacteals. The existence of these minute vessels had been known even to Galen and Erastistratus, but they had made nothing of their knowledge. Asellius says: "I observed that the nerves of the intestines were quite distinct from these white threads, and ran a different course. Struck with this new fact, I was silent for a time, thinking of the bitter warfare of words among anatomists as to the mesenteric veins and their purposes. When I came to myself, to satisfy my-self by an experiment, I pierced one of the largest cords with a scalpel. I hit the right point, and at once observed a white liquid like milk flowing from the divided vessel." Jehan Pecquet (1647), in the course of an experiment on the heart, observed the flow of chyle into the subclavian vein, and its identity with the chyle in the lacteals; and by further experiment found the thoracic duct, and the chyle flowing up it: " I perceived a white sub-stance, like milk, flowing from the vena cava ascendens into the pericardium, at the place where the right auricle had been I found these vessels (the thoracic duct) all along the dorsal vertebrae, lying on the spine, beneath the aorta. They swelled below a ligature; and when I relaxed it, I saw the milk carried to the orifices that I had observed in the subclavian vein." The existence of this duct, which is empty and collapsed after death, had been overlooked by Vesalius and all the great anatomists of his time. 3. The Gastric Juice.—Our knowledge about digestion dates back to the end of the 17th century, when Valisnieri first observed that the stomach of a dead animal contained a fluid which acted on certain bodies immersed in it—" a kind of aqua fortis." In 1752 Reaumur began his observations on this fluid, making birds swallow fine fenestrated tubes containing grain or meat, or sponges with threads attached; and observed that digestion consists in the dissolution of food, not in any sort of mechanical action or trituration. His observations were extended and perfected by Spallanzani (1777). Then came a period of uncertainty, with-out further advance; until in 1823 the French Academy offered a prize for the best work on the subject, and Tiedemann and Gmelin submitted their observations to them: " The work of Tiedemann and Gmelin is of especial interest to us on account of the great number of their experiments, from which came not only the absolute proof of the existence of the gastric juice, but also the study of the transformation of starch into glucose. Thus the theory of digestion entered a new phase: it was finally recognized, at least for certain substances, that digestion is not simply dissolution, but a true chemical transformation " (Claude Bernard, Physiologie opiratoire, 1879). Beaumont's experiments on Alexis St Martin (vide supra) were published in 1838. They were, of course, based on the work of the physiologists: " I make no claim to originality in my opinions as respects the existence and operation of the gastric juice. My experiments confirm the doctrines (with some modifications) taught by Spallanzani and many of the most enlightened physiological writers " (Beaumont's preface to his book). Eberle, in 1834, showed how this knowledge of the gastric juice might be turned to a practical use, by extracting it from the mucous membrane of the stomachs of animals after death: hence came the invention of the various preparations of pepsin. Later, Blondlot of Nancy, in 1842, studied the gastric juice by the method of a fistula, like that of St Martin. More recent observations have been made on the movements of the stomach during digestion, and on the influences of the nervous system on the process. The stomach is, of course not the only organ of digestion: the liver, the pancreas and the intestinal glands, all are concerned. The recent work of Pawlow and of Starling has greatly advanced our knowledge of the actions of the secretions from these organs. The whole chain of processes, nervous and chemical, psychical and physical, from the taking of food into the mouth to the expulsion of the waste residue, is now viewed in its entirety; and especial study has been given to the influences, nervous or chemical, which are exercised, as it were, on a particular tract of the digestive system, at the bidding of another tract. Pawlow, recognizing the importance of keeping the animals under the most normal conditions that were possible, and of studying the different tracts of the digestive system in animals not anaesthetized, yet free from pain or distress, made use of fistulae established at different points of the digestive canal, and was able to study the digestive juices at different stages during digestion, without causing pain to the animals. The work of Pawlow has been further developed by Professor Starling's recent work on the chemical substances produced in the body, during the act of digestion, to promote digestion. 4. Glycogen.—Claude Bernard's work on the assimilation and destruction of sugar in the body was begun in 1843. His discovery of the glycogenic action of the liver was made by keeping two dogs on different diets, one with sugar, the other without it, then killing them during digestion, and testing the blood in the veins coming from the liver: " What was my surprise when I found a considerable quantity of sugar in the hepatic veins of the dog that had been fed on meat only, and had been kept for eight days without sugar ! Finally, after many attempts—apres beaucoup d'essais et flusieurs illusions que je fus oblige de rectifier par des tdtonnementssucceeded in showing, that in dogs fed on meat the blood passing through the portal vein (from the stomach) does not contain sugar before it reaches the liver; but when it leaves the liver and comes by the hepatic veins into the inferior vena cava, this same blood contains a .;onsiderable quantity of a sugary substance (glucose) " (Nouvelle fonction du foie, Paris, 1853). 5. The Pancreas.—The 17th century was a time of very fanciful theories about the pancreas (Lindanus, Wharton, Bartholini), which need not be recalled here. But Sylvius (Francois de Bois) had the wisdom to see that the pancreas must be estimated, not according to its position, but according to its structure, as of the nature of the salivary glands. He urged his pupil, Regnier de Graaf, to study it by experiment, and de Graaf says: " I put my hand to the work; and though many times I despaired of success, yet at last, by the blessing of God on my work and prayers, in the year 1662 I discovered a way of collecting the pancreatic juice." By the method of a fistula he collected and studied the secretion of the pancreas; and by further experiment he refuted Bartholini's theory that the pancreas was a sort of appanage or " biliary vesicle " of the spleen. But he got no help from the chemistry of his time; he could no more discover the amylolytic action of the pancreatic secretion than Galvani could discover wireless telegraphy. Still, he did good work; and Claude Bernard, 18o years later, went back to de Graaf's method of the fistula. His observations, begun in 1846, received a prize from the French Academy in 185o. Sir Michael Foster says of them: " Valentin, it is true, had in 1844 not only inferred that the pancreatic juice had an action on starch, but confirmed his view by actual experiment with the juice expressed from the gland; and Eberle had suggested that the juice had some action on fat; but Bernard at one stroke made clear its threefold action. He showed that it on the one hand emulsified, and on the other hand split up into fatty acids and glycerine, the neutral fats; he clearly proved that it had a powerful action on starch, converting it into sugar; and lastly, he laid bare its remarkable action on proteid matters." At a later date it was discovered that the pancreas, beside its work in digestion, has an " internal secretion ": that it, like the thyroid gland and the suprarenal capsules, helps to keep the balance of the general chemistry of the whole body. Professor Schafer, writing in 1894, says on this subject: " It was discovered a few years ago by von Mering and Minkowski that if, instead of merely diverting its secretion, the pancreas is bodily removed, the metabolic processes of the organism, and especially the metabolism of carbo-hydrates, are entirely deranged, the result being the production of permanent diabetes. But if even a very small part of the gland is left within the body, the carbo-hydrate metabolism remains unaltered, and there is no diabetes. The small portion of the organ which has been allowed to remain (and which need not even be left in its proper place, but may be trans-planted under the skin or elsewhere) is sufficient, by the exchanges which go on between it and the blood generally, to prevent those serious consequences to the composition of the blood, and the general constitution of the body, which result from the complete removal of this organ." This fact, that complete removal of the pancreas, in a cat or a dog, may cause fatal diabetes, is of importance, because the pancreas in some cases of diabetes in man is diseased: but, at present, experiments on animals have not led to any certain or specific cure of diabetes in man. 6. The Growth of Bone.—The experiments made by du Hamel (1739-1843) on the growth of bone by deposit from the periosteum (the thin membrane ensheathing each bone) rose out of Belchier's observation (1735) that the bones take up the stain of madder mixed with the food. Du Hamel studied the whole subject very carefully, and discovered this bone-producing power of the periosteum, which is an important fact in all operations on the bones. As he puts it, in the title of one of his own memoirs, Les os croissent en grosseur par l'addition de couches osseuses qui tirent leur origine :du ptrioste, comme le corps' ligneux des Arbres augmente en grosseur par l'addition de couches ligneuses qui se foment dans l'tcorce. Byfeeding pigs at one time with dyed food, at another with undyed food, he obtained their bones in concentric layers alternately stained and unstained. His facts were confirmed by Bazan (1746) and Boehmer (1751); but his conclusions, unfortunately, were opposed by Haller. Still, he brought men to study the whole subject of the growth of bones, in length as well as in thickness, and the whole modellin of the bones, in adult life, by deposit and absorption. Bichat, John Hunter, Troja and Cruveilhier took up his work in physiology and in surgery. Later, from the point of view of surgery, Syme (1837) and Stanley (1849) made experiments on the growth of bone, and on the exfoliation of dead bone; and, after them, Oilier, whose influence on this part of surgical practice has been of the very highest value. 7. The Nervous System. A. The Nerve-Roots.—Through all the centuries between Galen, who lived in the time of Commodus, and Sir Charles Bell, who lived in the time of George III., no great advance was made in our knowledge of the nervous system. The way of experiment, which had led Galen far ahead of his age, was neglected, and everything was overwhelmed by theories. Bell in London and Magendie in Paris took up the experimental study of the nervous system about where Galen had left it. The question of priority of discovery does not concern us here: we may take Sir Michael Foster's judgment, that Magendie brought exact and full proof of the truth which Bell had divined rather than demonstrated, that the anterior and posterior roots of spinal nerves have essentially different functions—" a truth which is the very foundation of the physiology of the nervous system." The date of Bell's work is 1811, An Idea of a New Anatomy of the Brain, submitted for the Observation of the Author's Friends. In it he says: " Considering that the spinal nerves have a double root, and being of opinion that the properties of the nerves are derived from their connexions with the parts of the brain, I thought that I had an opportunity of putting my opinion to the test of experiment, and of proving at the same time that nerves of different endowments were in the same cord (the same nerve-trunk) and held together by the same sheath. On laying bare the roots of the spinal nerves I found that I could cut across the posterior fasciculus of nerves, which took its origin from the spinal marrow, without convulsing the muscles of the back; but that on touching the anterior fasciculus with the point of the knife, the muscles of the back were immediately convulsed. Such were my reasons for concluding that the cerebrum and cerebellum were parts distinct in function, and that every nerve.possessing a double function obtained that by having a double root. I now saw the meaning of the double connexion of the nerves with the spinal marrow, and also the cause of that seeming intricacy in the connexions of nerves throughout their course, which were not double at their origins." His other work, on the cranial nerves, which are " not double at their origins," bore fruit at once in surgery. Sir John Erichsen says of it: " Up to the time that Sir Charles Bell made his experiments on the nerves of the face, it was the common custom of surgeons to divide the facial nerve for the relief of neuralgia, tic douleureux; whereas it exercises, and was proved by Sir Charles Bell to exercise, no influence over sensation, and its division consequently for the relief of pain was a useless operation." B. Reflex Action.—The observations made by Sir Robert Boyle, Redi, Le Gallois and others on the reflex movements of decapitated vipers, frogs, eels and butterflies were of no great use from the point of view of physiology; but they led toward the discovery that nerve-power is stored in the spinal cord, and is liberated thence in action independent of the higher cerebral centres. Marshall Hall (1832-1837) discovered, by his experiments, that reflex actions are the work of definite groups of cells, set at certain points or levels in the cord; he proved the segmental structure of the cord, the existence of nerve-centres in it, and thus foreshadowed the discovery of the like centres in the brain. In his earlier writings (1832-33) he extended the principles of the doctrines of reflex action to the larynx, the pharynx and the sphincter muscles; later, in 1837, he demonstrated the course of nerve-impulses within the cord, from one level to another, and the effects of direct stimulation of the cord. Also he noted' the effects of opium and of strychnine on reflex action; and the reflex character of the 'convulsions that occur in certain diseases. C. The Medulla Oblongata and the Cerebellum.—Flourens, who was among the earliest students of the use of . chloroform, is best known for his experiments on the respiratory centre and the cerebellum. He localized the cells in the medulla that govern the reflex movement of respiration. Afterward came the discovery of cardiac and other centres in the neighbourhood of the respiratory centre. He showed also that the cerebellum is concerned with the equilibration and co-ordination of the muscles ; that an animal, a few days old, deprived of sensation and consciousness by removal of the cerebral hemispheres, was yet able to stand and to move forward, but when the cerebellum also was removed, lost all power of co-ordination (Recherches experimentales, Paris, 1842). And from the observations made by him and by others, it was found that the semicircular canals of the internal ears are the terminal organs of the sense of equilibration. D. The Vaso-Motor Nerves.—Claude Bernard, studying the sympathetic nervous system, discovered the vaso-motor nerves that control the calibre of the arteries. The question of priority between him and Brown Sequard need not be considered here. His first account of his work was communicated to the Societe de Biologie in December 1851. The following account of it is from his Lecons de physiologie operatoire (1870: 11 Let me remind you how I was led to discover the vaso-motor nerves. Starting from the clinical observation, made long ago, that in paralysed limbs you find at one time an increase of cold and at another an increase of heat, I thought that this contradiction might be explained by supposing that, side by side with the general action of the nervous system, the sympathetic nerve might have the function of presiding over the production of heat; that is to say, that in the case where the paralysed limb was chilled, I supposed the sympathetic nerve to be paralysed, as well as the motor nerves; while in the paralysed limbs that were not chilled the sympathetic nerve had retained its function, the systematic nerves alone having been attacked. This was a theory, that is to say, an idea, leading me to make experiments; and for these experiments I must find a sympathetic nerve-trunk of sufficient size, going to some organ that was easy to observe; and must divide the trunk to see what would happen to the heat-supply of the organ. You know that the rabbit's ear, and the cervical sympathetic of this animal, offered us the required conditions. So I divided this nerve; and, at once, the experiment gave the lie direct to my theory—Je coupai donc ce filet et aussitot 1'experience donna a mon hypothese le plus eclatant dementi. I had thought that the section of the nerve would suppress the function of nutrition, of calorification, over which the sympathetic system had been supposed to preside, and would cause the hollow of the ear to become chilled; and here was just the opposite, a very warm ear, with great dilatation of its vessels." The experiments of Budge and Waller (1853) and of Schiff (1856) threw light on the action of these vaso-motor nerves, and on the place of the vasomotor centre in the cord; and in 1858 Claude Bernard, by his experiments on the chorda tympani and the submaxillary gland, demonstrated their twofold influence, either to dilate or to constrict the vessels. " It is almost impossible to exaggerate the importance of these labours of Bernard on the vaso-motor nerves, since it is almost impossible to exaggerate the influence which our knowledge of the vaso-motor system, springing as it does from Bernard's researches as from its fount and origin, has exerted, is exerting, and in widening measure will continue to exert, on all our physiological and pathological conceptions, on medical practice, and on the conduct of human life. There is hardly a physiological discussion of any width in which we do not sooner or later come on vaso-motor questions " (Foster. Life of Claude Bernard). E. Cerebral Localization.—The study of the motor and sensory centres of the cerebral hemispheres began in clinical observation. Observation of cases, and examination of the brain after death (Bouillard, 1825, Dax,. 1836, Broca, 1861), led men to believe that a particular area of the left frontal lobe of the brain did indeed govern and permit the use of speech. Physiological experiments had nothing to do with the discovery of the speech centres. " Bouillard in 1825 collected a series of cases to show that the faculty of speech resided in the frontal lobes. In 1861 his views were brought by Aubertin before the notice of the Anthropological Society of Paris. Broca, who was present at the meeting, had a patient under his care who had been aphasic for twenty-one years, and who was in an almost moribund state. The autopsy proved of great interest, as it was found that the lesion was confined to the left side of the brain, and to what we now call the third frontal convolution. . . . In a subsequent series of fifteen typical cases examined, it was found that the lesion had destroyed, among other parts, the posterior part of the third frontal in fourteen " (Hamilton, Text-Book of Pathology). From this clinical fact, that the movements of speech depend on the integrity of a special area of the brain's surface, and from the facts of " Jacksonian epilepsy," and similar observations in medicine and surgery, began the experimental work of cerebral localization, by Hitzig, Goltz, Schiff, Ferrier, Yeo, Horsley, Beevor and many more. It would be hard to find a more striking instance of the familiar truth that science and practice work hand in hand. Again, the experimental method has thrown a flood of light on the minute anatomy of the central nervous system. For example, we have what is called Marchi's method; it was described to the Royal Commission (1906-8) by Dr Head and Sir Victor Horsley. It was found, by Professor Waller, that nerve-fibres, separated from the nerve-cells which nourish them, degenerate in a definite way. The application of this law experimentally has been of great value. Let me," says Dr Head, " just take a simile. Imagine a wall covered with creepers arising from several stems. If we wished to know from which of these stems any one branch takes its origin, we could cut one stem, and every leaf arising from it would die, marking out among the healthy foliage the offshoots of the divided stem. This is the principle that has been used in tracing the paths in the nervous system. owers, by applying this method, discovered the ascending tracts in the lateral columns of the spinal cord." If a microscopic section of a spinal cord, containing some fibres thus degenerate, be treated with osmic acid (Marchi's method), the degenerate fibres show dark: and in this way their course may be traced at all levels of the cord. Indeed, it may truly be said that, alike in anatomy and in physiology, the whole present knowledge of the brain, the spinal cord and the nerves, is in great measure due to the use of experiments on animals. And this knowledge is daily applied to the diagnosis and treatment of diseases and injuries of the central nervous system. " In the case of operations on the brain, you have to form your opinion as to what is going on entirely from your knowledge of the physiology of the brain: and that we owe, of course, in the greatest measure to the discoveries of Hitzig and Fritsch and Ferrier. That has all happened since 187o; and we are now able to cure epilepsy, we are able to cure abscess of the brain, and we are able to cure tumours of the brain. Then, in operations on the spinal cord, the same thing prevails. In fact, the first operation on the spinal cord I am responsible for, so that I know the history of the subject. The technique of that operation I owe entirely to experiments on animals. As regards operations on the peripheral nerves, Bell's operative treatment of neuralgia was guided entirely by his experiments on animals. Then we. come to the great subject of nerve suture. The initial work bearing upon that subject was carried out by Flourens, who was the first, to my knowledge, to make experiments on animals, to suture nerves together, to investigate their function " (Sir Victor Horsley, evidence before the Royal Commission, vol. iv. p. I24)., [These notes cover a part only of the results that have been obtained in physiology by the help of experiments on animals. The work of Boyle, Hunter, Lavoisier, Despretz, Regnault and Haldane, on animal heat and on respiration; of Petit, Dupuy, Breschet and Reid, on the sympathetic system; of Galvani, Volta, Haller, du Bois-Reymond and Pfluger, on muscular contraction—all these subjects have been left out, and many more. In his evidence before the Royal Commission (1875), Mr Darwin said: " I am fully convinced that physiology can progress only by the aid of experiments on living animals. I cannot think of any one step which has been made in physiology without that aid."] B. PATHOLOGY, BACTERIOLOGY AND THERAPEUTICS 1. Inflammation.—Pathology is so intimately associated with the work of the microscope, that it is a new study, in comparison with physiology. In 1850 the microscope was not in general use as it Is now; nor did men have the lenses, microtomes and staining fluids that are essential to modern histology. Bacteriology, again, is even younger than pathology. In 1875 ,it had hardly begun to exist. For example, in the evidence before the Royal Commission (1875) one of the witnesses said that they " believed they were beginning to get an idea of the nature of tubercle." Anthrax was the first disease studied by the methods of bacteriology; and in his evidence concerning this disease, Sir John Simon speaks of bacteriology as of a discovery wholly new and unexplored. Then, in 1881, came Koch's discovery of the bacillus of tubercle. But a great advance was made, in days before 1875, by the more general use of the microscope. Every change in the tissues during inflammation—the slowing of the blood stream in the capillary vessels, the escape of the leucocytes through their walls into the surrounding tissues, the stagnation of the blood in the affected part—all these were observed in such transparent structures as the web or the mesentery of the frog, the bat's wing, or the tadpole's tail, irritated by a drop of acid, or a crystal of salt, or a scratch with a needle. It was in the course of observations of this kind that Wharton Jones observed the rhythmical contraction of veins, and Waller and Cohnheim observed the escape of the leucocytes, diapedesis, through the walls of the capillaries. From these simple experiments under the microscope arose all our. present knowledge of the minute processes of inflammation. Later came the work of Metschnikoff and others, showing the importance of diapedesis in relation to the presence of bacteria in the tissues. 2. Suppuration and Wound-Infection.—Practically every case of suppuration, wound-infection or " blood-poisoning," all abscesses, boils, carbuncles, and all cases of puerperal fever, septicaemia, or pyaemia, are due to infection, either from without or from within the body, by various forms of micro-organisms. The same is true of every case of erysipelas, or cellulitis, or acute gangrene—in short, of the whole multitude of " septic " diseases. The work done on these micro-cocci, and on other pathogenic micro-organisms, involved the study of the phases, antagonisms and preferences of each kind, their range of variation and of virulence, their products, and the influences on them of air, light, heat and chemical agents. The beginning of Lister's work was in Pasteur's study of the souring of milk, about 1856. Pasteur's discovery, that lactic fermentation was due to a special micro-organism, opened the way for modern surgery. Lister had been long studying the chemical changes in decomposing blood and other animal fluids; now he brought these studies into line with Pasteur's work. Thus, in T867, In his first published writing on the antiseptic treatment of compound fractures, he speaks as follows: " We find that a flood of light has been thrown upon this most important subject by the philosophic writing of M. Pasteur, who has demonstrated, by thoroughly convincing evidence, that it is not to its oxygen, or to any of its gaseous constituents, that the air owes this property (of producing decomposition), but to minute particles suspended in it, which are the germs of various low forms of life long since revealed by the microscope, and regarded as merely accidental concomitants of putrescence; but now shown by Pasteur to be its essential cause." The present antiseptic method includes the aseptic method. That is to say, the instruments and other accessories of an operation are " sterilized " by heat; and, where heat cannot be applied, as to the patient's skin and the surgeon's hands, antiseptics are used. Modern surgery is both antiseptic and aseptic. 3. Anthrax.-The bacillus of anthrax (charbon, malignant pustule, wool-sorter's disease) was the first specific micro-organism discovered. Rayer and Davaine (185o) observed the petits bdtonnets in the blood of sheep dead of the disease; and in 1863, when Pasteur's observations on lactic-acid fermentation were published, Davaine recognized that the bdtonnets were not blood crystals, but living organisms. Koch afterward succeeded in cultivating the bacillus, and in reproducing the disease in animals by inoculation from these cultures. Pasteur's discovery of preventive inoculation of animals against the disease was communicated to the Academie des Sciences in February 1881; and in May of that year he gave his public demonstration at Pouilly-le-Fort. Two months later, at the International Medical Congress in London, he spoke as follows of this discovery: " . La methode que je viens de vous exposer pour obtenir des vaccins du charbon etait a peine connue qu'elle passait dans la grande pratique pour prevenir 1'affection charbonneuse. La France perd chaque annee pour une valeur de plus de vingt millions d'animaux frappes du charbon, plus de 30 millions, m'a dit une des personnes a.utorisees de notre Ministere de l'Agriculture; mais des statistiques exactes font encore defaut. On me demanda de mettre a 1'epreuveles resultats qui precedent par une grande experience publique, a Pouilly-le-Fort, pres de Melun. . . Je la resume en quelques mots; 50 moutons furent mis a ma disposition, nous en vaccinames 25, les 25 autres ne subirent aucun traitement. Quinze jours apres environ, les 5o moutons furent inocules par le microbe charbonneux le plus virulent. Les 25 vaccines resisterent; les 25 non-vaccines moururent, tous charbonneux, en cinquante heures. Depuis tors, dans mon laboratoire, on ne peut plus suffire a preparer assez de vaccin pour les demandes des fermiers. En quinze jours, nous avons vaccine clans les departements voisins de Paris pres de 20,000 moutons et un grand nombre de bceufs, de vaches et de chevaux." The extent of this preventive vaccination may be judged from the fact that a single institute, the Sero-Therapeutic Institute of Milan, in a single year (1897-98) sent out 165,000 tubes of anti-charbon vaccine, enough to inoculate 33,734 cattle and 98,792 sheep. In France, during the years 1882-93, more than three million sheep and nearly half a million cattle were inoculated. In the Annales de l'Inslitut Pasteur, March 1894, M. Chamberland published the results of these twelve years in a paper entitled " Resultats pratiques des vaccinations contre le charbon et le rouget en France." The mortality from charbon, before vaccination, was 10 % among sheep and 5% among cattle, according to estimates made by veterinary surgeons all over the country. With vaccination, the whole loss of sheep was about 1%; the average for the twelve years was 0.94. The loss of vaccinated cattle was still less; for the twelve years it was 0.34, or about one-third %. The annual reports sent to M. Chamber-land by the veterinary surgeons represent not more than half of the work. " A certain number of veterinary surgeons neglect to send their reports at the end of the year. The number of reports that come to us even tends to become less each year. The fact is, that many veterinary surgeons who perform vaccinations every year content themselves with writing, 'The results are always very good ; it is useless to send you reports that are always the same.' We have every reason to believe, as a matter of fact, that those who send no reports are satisfied; for if anything goes wrong with the herds, they do not fail to let us know it at once by special letters." The following tables, from M. Chamberland's paper, give the results of Pasteur's treatment against charbon during 1882-93, and against rouget (swine-measles) during 1886-92. It is to be noted that the mortality from rouget among swine, in years before vaccination, was much higher than that from charbon among sheep and cattle: " It was about 20%; a certain number of reports speak of losses of 6o and even 8o%; so that almost all the veterinary surgeons are loud in their praises of the new vaccination." It would be too much to say that every country, in every year, has obtained results with this anthrax-vaccine equal to those which have been obtained in France. Nor would it be reasonable to advocate the compulsory or wholesale use of the vaccine in the British Islands, where anthrax is rare. For the general value of the vaccine, however, we have this striking fact, that the use of it has steadily increased year by year. A note from the Pasteur Institute, dated November29, 1909, says: Depuis 1882 jusqu'au Janvier 1909, 'I a ete expedie, pour la France, 8,400,000 doses de vaccin anti-charbonneux pour moutons, 1,300,000 pour bceufs. Pour 1'etranger, 8,5oo,000 doses pour moutons, 6,200,000 pour bceufs. Le nombre de doses augmente d'annee en annee, de sorte que pour I'annee 1908 seule it faut compter en tout 1,500,000 doses pour moutons (France et etranger) 1,100,000 pour bceufs." (Two doses are used for each animal.) It remains to be added that a serum-treatment, introduced by Sctavo, has been found of considerable -'alue in cases of anthrax (malignant pustule) occurring in man.
End of Article: VIVISECTION

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