THE ANTHRAX BACILLUS 387 



the capillaries will be seen to be stuffed full of bacilli, and hemor- 

 rhages, probably due to rupture of capillaries by the mechanical pressure 

 of the bacilli which are developing within them, may occur. The patho- 

 logical lesions in animals infected by anthrax are not marked except 

 in the spleen, which, as in other forms of septicaemia, is greatly enlarged. 



Occurrence in Cattle and Sheep. Cattle and sheep are affected chiefly 

 with the intestinal form of anthrax, infection in these animals com- 

 monly resulting from the ingestion of food containing spores. The 

 bacillus itself, in the absence of spores, is quickly destroyed by the 

 gastric juice. The disease usually takes a rapid course, and the mor- 

 tality is high 70 to 80 per cent. The pathological lesions consist of 

 numerous ecchymoses, enlargement of the lymphatic glands, serous, 

 fatty, and hemorrhagic infiltration of the mediastinum and mesentery, 

 of the mucous membranes of the pharynx and larynx, and particularly 

 of the duodenum, great enlargement of the spleen, and parenchymatous 

 changes in the lymphatic organs. The blood is very dark and tar-like. 

 Bacilli are present in enormous masses. 



Sheep are also subject to external anthrax, infection taking place 

 by way of the skin ; cattle are seldom infected in this way. At the point 

 of inoculation there develops a hard, circumscribed boil the so- 

 called anthrax carbuncle; or there may be diffuse oedema, with great 

 swelling of the parts. When death occurs the appearances are similar 

 to those in intestinal anthrax, except that the duodenum is usually 

 less affected; but in all cases metastasis, occurs in various parts of the 

 body, brought about, no doubt, by previous hemorrhages. 



Occurrence in Man. The disease does not occur spontaneously in 

 man, but always results from infection, either through the skin, the 

 intestines, or occasionally by inhalation through the lungs. It is usually 

 produced by cutaneous infection through inoculation of exposed sur- 

 faces the hands, arms, or face. Infection of the face or neck would 

 seem to be the most dangerous, the mortality in such cases being 26 

 per cent.; while infection of the extremities is rarely fatal. 



External anthrax in man is similar to this form of the disease in 

 animals. There are two forms: malignant pustule or carbuncle, and, 

 less commonly, malignant anthrax oedema. 



In malignant pustule, at the site of inoculations, a small papule 

 develops, which becomes vesicular. Inflammatory induration extends 

 around this, and within thirty-six hours there is a dark-brownish eschar 

 in the centre, at a little distance from which there may be a series of 

 small vesicles. The brawny induration may be extreme. There may 

 also be considerable oedema of the parts. In most cases there is no fever; 

 or the temperature at first rises rapidly and the febrile phenomena are 

 marked. Death may take place in from three to five days. In cases 

 which recover the symptoms are slighter. In the mildest form there 

 may be only slight swelling. 



Malignant anthrax oedema occurs in the eyelids, and also in the head 

 and neck, sometimes the hand and arm. It is characterized by the 

 absence of the papule and vesicle forms, and by the most extensive 



