152 Chapter VI 



detailed investigation in ray laboratory to answer these questions. 

 He was able to convince himself, in agreement with the statements 

 of his predecessors, that not only was the serum of dog's blood not 

 bactericidal for the anthrax bacillus, but that the plasma of the blood 

 is no more so. The fluid of the aseptic pleural exudation obtained 

 after injection of gluten-casein, was likewise incapable of killing the 

 anthrax bacillus. When Gengou, by means of centrifugalisation, 

 isolated the leucocytes from these exudations, washed them in 

 physiological salt solution, froze them, and then macerated them in 

 broth, he obtained suspensions of white corpuscles, to which he 

 added bacilli. He was able to demonstrate that when the exudations 

 contained macrophages principally, as is observed in exudations 

 taken at the end of two or three days, the bactericidal power of 

 the suspensions was nil or insignificant. When, on the other hand, 

 the leucocytes came from exudations only twenty-four hours old and 

 were composed almost exclusively of microphages, the destructive 

 action on the bacilli of the extract of the microphages in broth 

 was most marked. Now it is fully demonstrated that in the 

 exudation set up in the refractory dog by the injection of anthrax 

 bacilli, it is especially the microphages which exhibit the phagocytic 

 reaction against this bacillus. 



This is how the question of the immunity of the dog from 

 anthrax stands at present. The natural immunity of this species, 

 which although not unlimited, is very real, depends on the activity 

 of phagocytes. These elements, under the stimulus of the bacillus 

 and its products, exhibit a positive chemiotaxis of the most marked 

 character, they approach the bacilli, ingest them by a physiological 

 act, and destroy them by means of a substance which is not found in 

 either the plasma or the blood serum, but which can be demonstrated 

 in an extract of the microphages. 



In spite of the uniformity and precision of these data, it is 

 impossible to rest satisfied with describing, as an example of natural 

 immunity from anthrax, the single case of the dog. If the resistance 

 of the rat against this disease was merely of historical interest because 

 of the large number of works devoted to this question, we might 

 [162] relegate it to the chapter reserved for the history of our knowledge 

 on immunity. But it is not so. The anthrax of rats is a subject 

 full of very valuable instruction, and von Behring was quite justified 

 in saying that whoever wished to get a true conception of natural 

 immunity from a virus should pay special attention to this example. 



