284 ANTHRAX. 



The lymphatic system generally is much affected. The 

 glands, especially the mediastinal, mesenteric, and cervical 

 glands, are enlarged and surrounded by oedematous tissue, 

 the lymphatic vessels are swollen, and both glands and 

 vessels may contain numberless bacilli. The heart may be 

 in a state of acute cloudy swelling, and the blood in its 

 cavities contains bacilli, though in smaller numbers than in 

 the capillaries. The intestines are enormously congested, 

 the epithelium catarrhal and the lumen filled with a bloody 

 fluid. From all the organs the bacilli can be easily isolated 

 by stroke cultures on agar. 



It is important to note the existence of great differences 

 in susceptibility to anthrax in different species of animals. 

 Thus the ox, sheep (except those of Algeria), guinea-pig, 

 and mouse are all very susceptible, the rabbit slightly less 

 so. The last three are of course most used for experimental 

 inoculation. We have no data to determine whether the 

 disease occurs among these in the wild state. Less sus- 

 ceptible than this group are the horse, deer, goat, in which 

 the disease occurs from time to time in nature, as it also 

 does, though rarely, in the pig. The human subject may 

 be placed next in order of susceptibility, man thus occupy- 

 ing a medium position between the highly susceptible and 

 the relatively immune animals. The white rat is highly 

 immune to the disease, while the brown rat is susceptible. 

 Adult carnivora are also very immune, and the birds and 

 amphibia are in the same position. 



With these differences in susceptibility there are also great 

 variations in the pathological effects produced in the natural 

 or artificial disease. This is especially the case when we 

 consider the distribution of the bacilli in the body of an 

 animal dead of the affection. Instead of the widespread 

 occurrence described above, they may be confined to the 

 point where they first gained access to the body and the 

 lymphatic system in relation to it, or may be only very 

 rarely scattered in organs such as the spleen (which is 

 often not enlarged), the lungs, or kidneys. Nevertheless the 

 cellular structure of the organs even in such a case may 



