154 Chapter VI 



relative, not absolute. "The anthrax bacilli "—he says— "die in rat's 

 serum in vitro ; and in the cases where the inoculation of these 

 animals with the anthrax virus is not fatal, it is at least reasonable to 

 assume that the blood fluid likewise produces this protection in 

 the organism of the living rat. Now, an immunity that manifests 

 itself without the aid of any activity of the cell must undoubtedly 

 be regarded as being of a humoral character '' (loc, cit. p. 202). 

 Let us begin by analysing the facts as presented in rats into 

 [164] whose subcutaneous tissue we have injected anthrax virus. A certain 

 number of them resist, without exhibiting any lesion other than 

 a certain exudative inflammation at the seat of inoculation. The 

 exudation is, in this case, very rich in leucocytes which quickly 

 exert their phagocytic function and destroy the ingested bacilli. 

 In this reaction it is the microphages that play the chief part, the 

 macrophages intervening later and in a much less pronounced fashion. 

 Usually, however, the inoculated rats exhibit a more serious illness : 

 the bacilli multiply at the point of inoculation and excite the 

 formation of an extensive oedema, rich in serous fluid, transparent, 

 and very poor in leucocytes. It is only later that these cells inter- 

 vene in any considerable number. The exudation becomes thicker 

 and turbid, the numerous white corpuscles devour the bacilli and 

 cause their disappearance. Under the influence of this marked 

 reaction the animals in most cases recover, as has already been 

 established by Franks But even in those individuals which succumb 

 to anthrax death occurs more or less tardily, an examination of the 

 internal organs then revealing a considerable phagocytic reaction. 

 The spleen, often of enormous size, contains numerous macrophages 

 which are filled with normal or more or less altered bacilli. In the 

 liver these macrophages, which have devoured several microphages 

 and some bacteria, are also found (Figs. 22 and 23). 



When instead of bacteria in the condition of rods, anthrax spores 

 are inoculated subcutaneously or into the anterior chamber of the 

 eye, we can observe their germination. There is developed a whole 

 generation of bacilli which behave like those we have already 

 described, that is to say, they excite an exudation and are ultimately 

 digested within the phagocytes (Figs. 24 and 25). All these pheno- 

 mena of phagocytosis I described in detail more than ten years ago 

 in my memoir on the anthrax of rats 2. Since then not a single 



1 Centralhl.f. Bacterlol. u. Parasitenk, Jena, 188S, Bd. iv, SS. 710, 737. 



2 Ann. de VInst. Pasteur^ Paris, 1890, t. iv, p. 193. 



