case of any severity, a single joint of the meat will have an entirely different naked-eye appearance to healthy meat. In different parts there may be tumours which are filled with a collection of gelatinous, citron-coloured matter, infiltrating into the subcutaneous connective and intermuscular textures and destroying the tissues; in these parts decomposition is mostly more advanced than in others. The blood is black, fluid, and stains the tissues everywhere. The heart is soft and flaccid, with hemorrhages in its substance. There are special changes in the spleen. As a rule the spleen is enormously enlarged, sometimes ruptured, it is jet black, and from its cut surface flows a fluid which has been likened to china ink. The liver, the kidneys, the lungs, are all congested, and here and there minute hæmorrhages or larger extravasations of blood are to be seen. A microscopical examination of the blood of the heart, or the inky fluid, or the tissue of the spleen, shows innumerable little rods; the rods vary a little in size, according to the animal from whence they have been derived; they are usually from 5-20μ long and 1-1.25μ broad; within the body they do not form spores. The rods stain intensely with aniline dyes; they are straight, or sometimes slightly curved, rigid, and have no power of self-movement. They readily admit of cultivation in feebly alkaline broth, or in nutrient gelatin, or in blood serum, or on potatoes. All the cultivations have a more or less characteristic appearance, so that a bacteriologist can in not a few cases identify the growth by examination with a low magnifying power; for instance, in a stab culture in gelatin there is first a whitish line in the track of the inoculating needle, and from it fine filaments spread out in the gelatin. Occasionally a little isolated spot develops, from which rays extend in all directions like the silky filaments of thistle-down (Crookshank). The gelatin slowly liquefies and the growth subsides as a flocculent mass. By artificial cultivations the rods may develop into threads of great length. Rods cultivated on the surface of a solid medium form spores, or if a little anthrax blood be taken and allowed to dry with free access of air, spores are formed, and once formed preserve their vitality for years. An inoculation with these spores of a small animal, such as a mouse or guinea-pig, produces death in from twenty-four to forty-eight hours. Sheep fed on potatoes, which have been the medium for cultivating the bacillus, die in a few days. It used to be taught that pigs have an immunity from the disease, but this Prof. Crookshank has shown to be erroneous. He has produced anthrax in swine by feeding them on anthrax offal; by injection of the blood of a bullock which had died of anthrax, and by injection of artificial cultures, he has also reproduced the disease in guinea-pigs and mice by inoculation of blood from a pig which had died of anthrax. The general and post-mortem signs of anthrax in the pig he thus describes : From the point of entrance of the virus there extends a yellowish jelly-like ædema of the subcutaneous areolar tissue. If the disease is induced by ingestion of anthrax offal, the tonsils are found to be ulcerated, and constitute the point of access of the bacilli to the blood. In such cases the characteristic symptom is enormous swelling around the throat. If the inoculation is by hypodermic injection, the same oedematous infiltration of the tissues occurs at the place selected for inoculation. Death may occur very rapidly in twenty-four hours, or not until five or six days. There is usually a rash-like discolouration of the skin, sometimes loss of power over the limbs, and a general weakness and disinclination to move; or the animal may lie helplessly on its belly and utter plaintive cries when disturbed. At the post-mortem the most characteristic feature is the gelatinous oedema which in the case of ingestion of offal is found around the throat. There is usually congestion of all the organs and engorgements of the heart and large vessels, fluid in the cavity of the chest and abdomen, and enlargement and hæmorrhage into the lymphatic glands. There is in some cases inflammation of the intestines, and submucous and subserous hæmorrhages. The spleen may be normal in size, pale and flabby, and the liver also only slightly congested and friable; in other cases the condition is characteristic, the spleen is the seat of hæmorrhage, causing more or less local enlargement, superficially of a deep purple colour; the liver also may be greatly congested, very friable and marked with purple patches. The examination of the blood of the heart and spleen for anthrax bacilli must be carried out with great perseverance and discrimination, as they are only present in small numbers, and in some cases have given place entirely to septic organisms. Inoculation with the blood will correspondingly produce either typical anthrax or malignant oedema. or some other form of septicemia. Possibly in the cases from ingestion of offal the ulcerated condition of the throat affords a nidus and means of access for septic organisms also, and it is well known that blood in a state of putrefaction may contain the bacillus of malignant oedema. In the presence of putrefactive organisms the anthrax bacillus rapidly disappears. If, therefore, inoculation of guinea-pigs or mice is used as a test for ascertaining the nature of an outbreak in swine, it must not be concluded, if Pasteur's or some other form of septicemia result, that the disease was not anthrax; while, on the other hand, the discovery of the anthrax bacillus in the blood of the pig, or the production by inoculation of anthrax in guinea-pigs or mice with the blood of the pig, is positive evidence as to the nature of the original disease. (475) Charbon Symptomatique. This is a common epizootic in this country and the Continent; it has long been known under various names, such as quarter ill, black leg, and others, and has been confused with anthrax, to which it bears some resemblance. Our knowledge of the malady is derived from the researches of Arloing, Cornevin, and Thomas in France and by Dowdeswell in this country. The disease is caused by a special micro-organism-the clostridium of symptomatic anthrax. The microbes are rods specially distinguished from the bacillus anthracis by being rounded at the ends and having at one end mostly a shining spore, and by being motile. The rods can be easily cultivated, but contrary to the b. anthracis they grow best with exclusion of air because they are anærobic. The pathological signs after death differ from anthrax in at least two important characters-the spleen is neither enlarged nor black and the blood has not the black fluid appearance as in anthrax. Otherwise there is the same oedema, the same friability of the muscles, hæmorrhages into the tissues of organs, &c. There can be no doubt of the flesh being injurious, and any animal affected with the disease should not be used for the purpose of human food. Mr. Dowdeswell remarks,1 "In the case of "On the Etiology of Charbon Symptomatique," by G. F. Dowdeswell. M. A., F.L.S., F.C.S., &c. Thirteenth Annual Report of the Local Government Board, Supplement, 1883, 1884. 1 46 rodents I have found the flesh of infected animals, i.e., the tissues of the parts principally affected, to be distinctly toxical to others of the same species when eaten. Guinea-pigs, like rats, are omnivorous, and readily eat the flesh of their dead comrades however well they are supplied with other food; in two experiments I found that giving the limb of an infected animal to another, in each case occasioned its death some days subsequently. This agrees with the accounts in this country of persons who have been poisoned, though not fatally, by eating the flesh of infected cattle." |