ANTHRAX IN ANIMALS 343 



may be said ' to occupy 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 sus- 

 ceptible. Adult carnivora are also very immune, and 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 







Fig. 103. — Portion of kidney of a guinea-pig dead of anthrax, 

 showing the bacilli in the capillaries, especially of the glomerulus. 

 Paraffin section ; stained by Gram's method and Bismarck-brown. 

 x300. 



artificial disease. This is especially the case when we consider 

 the distribution of the bacilli in the bodies of the less susceptible 

 animals. 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 sparsely scattered in organs such as the spleen 

 (which is often not enlarged), the lungs, or kidneys. Neverthe- 

 less the cellular structure of the organs even in such a case may 

 show changes, a fact which is important, when we consider the 

 essential pathology of the disease. 



