INFECTION AND IMMUNITY. 559 



almost instantly the peculiar disintegration of the bac- 

 teria, as observed in the peritoneum of the immune ani- 

 mal, could be detected. This latter observation is of 

 the utmost importance in its bearing on Buchner's 

 hypothesis, for we see here a serum from an immune 

 animal that is capable of conferring immunity ; capable, 

 on injection into a susceptible animal, of endowing its 

 fluids with the peculiar disintegrating, germicidal 

 function noted in the peritoneum of the immune ani- 

 mal from which the serum originated ; incapable of 

 bacteriolytic activity outside the body, but the influ- 

 ence of which in the peritoneum of a susceptible ani- 

 mal is to call forth at once this interesting phenomenon. 

 Manifestly the germicidal substance in this case is 

 contained neither in the protective serum nor in the 

 peritoneum of the susceptible animal before receiving 

 the serum, but either is generated by the tissues as a 

 result of the specific irritation by a something con- 

 tained in this serum — i. e., in consequence of a reac- 

 tion on the part of the peritoneal tissues, or possibly 

 those of the entire animal — or else it is, as Ehrlich 

 conceives it to be, a complex whose physiological 

 activity depends upon the union of at least two essen- 

 tial groups — the one present in the serum of the im- 

 mune animal, and the other in the fluids of the normal 

 animal. 



In more recent investigations Pfeiffer, in association 

 with Marx, has found that the antitoxic substances in 

 cholera-immune animals are much more abundant in 

 the blood-building organs — spleen, lymphatic glands, 

 and bone-marrow — than in either the blood or other 

 tissues.' 



1 Pfeiffer und Marx : Deutsche med. Wochenschrift, 1898, No. 3. 



