192 Chapter VII 



that employed by Wassermann. Consequently the control guinea- 

 pigs which received such a huge quantity of the typhoid cocco-bacilli, 

 going beyond 40 times the limit of their natural immunity, require 

 to be preserved from death by the injection of a large quantity of 

 blood serum heated to 60 C. from the normal rabbit. This serum, 

 deprived of its cytase, retains its other properties, by which the 

 organism of the guinea-pig profits, especially exercising a stimulating 

 action on the phagocytes of the guinea-pig. The immunity of Wasser- 

 manri's control animals was, then, really an acquired immunity, the 

 result of the introduction into their organism of the stimulating 

 serum of the rabbit. For this reason an analysis of the work of this 

 observer must be postponed until we treat of the phenomena of 

 acquired immunity under the influence of normal serums. 



We must, then, persist in the opinion that the plasmas of the 

 normal animal, containing no cytases, cannot play a bactericidal part 

 in natural immunity, a part which devolves upon the cytase contained 

 within the phagocytes. 



This result accords well, also, with the whole of the facts bearing 

 on the destruction of micro-organisms in the animal body. The 

 transformation into granules of the attenuated cholera vibrios that 

 is sometimes observed in the peritoneal cavity during the period of 

 phagolysis, and the absence of this transformation under conditions 

 where the peritoneal leucocytes are protected against this injury, is 

 [203] clearly explained. In the first case, Pfeiffer's phenomenon is set up 

 by the bactericidal substance which has escaped from the leucocytes 

 that have been altered by the foreign substances injected into the 

 peritoneal cavity ; in the second case, this phenomenon is not pro- 

 duced because the leucocytes remain intact. The absence of this 

 granular transformation in the anterior chamber of the eye and in 

 the subcutaneous tissue is also readily explained by the fact that the 

 bactericidal substance, not being present in the blood plasma, cannot 

 pass into the exudations of the eye and subcutaneous tissue 1 . 



1 Since Nuttall's first paper appeared a certain bactericidal action of the aqueous 

 humour has been observed. This fact should be taken into consideration in the 

 study of the question of the phagocytic origin of the bactericidal substance of the 

 body fluids. If this substance really comes from the phagocytes, it should not be found 

 in the transparent aqueous humour that contains no, or almost no, leucocytes. Now 

 this fluid sometimes destroys a certain number of micro-organisms. This apparent 

 contradiction is explained by the fact that the bactericidal action may be exercised 

 by all kinds of fluids, such as physiological salt solution, nutritive broths, etc. The 

 bactericidal property of the aqueous humour comes into this category. Its action is, 



