ANTHRAX. 473 



black. The various internal organs, as well as the other structures, 

 are, frequently, discoloured by the infiltration of dark, altered 

 blood. Generally, the spleen is distended with dark-coloured blood, 

 and its tissues are softened and broken up, almost to the con- 

 sistence of a fluid. The spleen in the large majority of cases, is 

 much heavier than usual, and is affected in almost every case of 

 this disease. When swellings have appeared about the neck, a 

 large quantity of thick yellowish fluid will be found under the 

 skin of that part. Similar fluid may be found in the interior of 

 the chest and belly. The mucous membrane which lines the wind- 

 pipe exhibits an inflamed appearance. The air-passages are often 

 filled with bloody foam. The rigor mortis (stiffness of the 

 muscles after death) lasts but a short time, and the body rapidly 

 decomposes. 



NATURE OF THE DISEASE.— Anthrax is caused by the presence, in the 

 blood and tissues, of the bacillus anthracis, which is one of the disease-pro- 

 ducing bacteria (p. 448), and may be found after death in great abundance 

 in the internal organs, and especially in the spleen. These microbes occur 

 in the shape of short rods, which appear incapable of forming spores in the 

 living body of an infected animal, or even after its death, as long as the skin 

 and mucous membranes remain intact ; a free supply of oxygen being seemingly 

 necessary for their spore formation. It appears that the cause of the symp- 

 toms of anthrax is the poison or poisons formed by the ferment or 

 ferments manufactured by the bacilli anthracis. In support of this view we 

 have the fact that all the symptoms of anthrax can become fully developed, 

 and even death ensue. Avithout the rods (bacilli) being found, except in very 

 small numbers, in the blood. 



The anthrax germ gains entrance into the blood, as a rule, by 

 means of the forage which the animal eats, or by the water he 

 drinks, as has been frequently proved by the fact of the disease 

 having been communicated by contaminated drinking water. 

 Pasteur, when experimenting on animals to whom he gave forage 

 moistened with a fluid containing these germs, found that the 

 animals' liability to contract the disease in this manner was greatly 

 increased when their mouths were sore, and when the food con- 

 tained rough substances, such as thistles, which are apt to wound 

 the mucous membrane of the mouth. He also found that the 

 mouth was almost always the part which first became affected. 

 These microbes can seldom gain entrance into the system of the 

 horse by means of the breathed-in air. Bollinger has shown that 

 flies taken from the dead body of an animal which had died of 

 anthrax, are capable of communicating the disease by inoculation. 

 Although the microbes of anthrax may be carried directly from 

 one animal to another, the vast majority of cases occur from trans- 

 ference at a time when they were living outside of the animal's 

 body, as, for instance, on infected pasture. We find in human 



