344 ANTHKAX 



Experimental Inoculation. — Of the animals commonly used 

 in laboratory work, mice and guinea-pigs are the most susceptible 

 to anthrax, and are generally used for test inoculations. If a 

 small quantity of anthrax bacilli be injected into the sub- 

 cutaneous tissue of a guinea-pig, a fatal result follows, usually 

 within two days. Post mortem, around the site of inoculation the 

 tissues, owing to intense inflammatory oedema, are swollen and 

 gelatinous in appearance, small haemorrhages are often present, 

 and on microscopic examination numerous bacilli are seen. 

 The internal organs show congestion and cloudy swelling, with 

 sometimes small haemorrhages, and their capillaries contain 

 enormous numbers of bacilli, as has already been described in 

 the case of the ox (Fig. 103) ; the spleen also shows a corre- 

 sponding condition. Highly susceptible animals may be infected 

 by being made to inhale the bacilli or their spores, and also by 

 being fed with spores, a general infection rapidly occurring by 

 both methods. 



Anthrax in the Human Subject. — As we have noted, man 

 occupies a middle position in the scale of susceptibility to anthrax. 

 It is always communicated to him from animals directly or in- 

 directly, and usually is seen among those whose trade leads them 

 to handle the carcases or skins of animals which have died of the 

 disease. It occurs in two principal forms, the main difference 

 between which is due to the site of entrance of the organism into 

 the body. In one, the path of entrance is through cuts or abra- 

 sions in the skin, or through the hair follicles. A local condition 

 called a " malignant pustule " develops, which may lead to a 

 general infection. This variety occurs chiefly among butchers 

 and those who work among hides (foreign ones especially). In 

 Britain the*workers of the latter class chiefly liable are the hide- 

 porters and hide-workers in South-Eastern London. Occasion- 

 ally the disease has been contracted from anthrax spores in 

 shaving-brushes. In the other variety of the disease the site of 

 infection is the trachea and bronchi, and here a fatal result 

 almost always follows. The cause is the inhalation of dust or 

 threads from wool, hair, or bristles, which have been taken from 

 animals dead of the disease, and which have been contaminated 

 with blood or secretions containing the bacilli, these having 

 afterwards formed spores. This variety is often referred to as 

 " woolsorter's disease," from its occurring in the centres of the 

 woolstapling trade (in England, chiefly in Yorkshire), but it also 

 is found in places where there are hair, brush, or carpet factories. 

 (1) Malignant Pustule. — This usually occurs on the exposed 

 surfaces — the face, hands, forearms, and back, the last being a 



