RELATION OF LEUKOCYTES TO IMMUNITY 305 



Moxter, 32 a little later, working with cholera spirilla, also came 

 to the conclusion that the leukocytic bactericidal substances were not 

 identical with those found in the blood serum. Fetter son, 33 too, made 

 thorough investigations into the nature of the bactericidal substances 

 extracted from the leukocytes, and, working chiefly with B. proteus 

 and B. anthracis, found such substances in the leukocytes of dogs, 

 rabbits, and guinea pigs active against the bacteria mentioned above, 

 but failed to find them active, at least in guinea pig and cat leuko- 

 cytes, against B. typhosus or the cholera spirillum. He expresses the 

 opinion that bactericidal leukocytic substances are normally given 

 up to the blood in minute quantity only or not at all, and that these 

 substances hold no definite relationship to the bactericidal sub- 

 stances found in blood serum. In a later investigation he showed 

 that the "endolysins," as he now calls the leukocytic bactericidal 

 substances, may, like many enzymes and serum bacteriolysins, be 

 precipitated out of solution with alcohol and ether ; but he separates 

 them absolutely from serum lysins and complement. The latter, 

 while they may be, in part at least, secreted by the leukocytes, are, 

 according to Pe'tterson, induced easily to come out of the cells during 

 life by slight injury or other stimulation, while the endolysins them- 

 selves are abstracted from the cells only after extensive extraction or 

 maceration. 



Schneider 34 has come to similar conclusions and speaks of the 

 endocellular bactericidal substances as "Leukine." In a recent in- 

 vestigation of the same subject the writer 35 has in all essentials con- 

 firmed Schattenf roh's original conclusions regarding the heat sta- 

 bility of the extracted leukocytic bactericidal substances, and has 

 shown that after inactivation by heat these substances are not reacti- 

 vable by the addition of fresh leukocytic extracts, and that the yield 

 obtained from the leukocytes of immunized animals is not greater 

 than that obtained from normal leukocytes. 



It appears, therefore, that, contrary to Metchnikoff's first sup- 

 position, the enzymes which bring about the digestion of phagocyted 

 bacteria within the cell are not identical with those which bring 

 about a similar extracellular digestion. In addition to the demon- 

 stration of a definitely different structure possessed by the bacteri- 

 cidal leukocytic extracts, as evidenced by their heat stability, we have 

 the negative evidence that neither true alexin nor sensitizers have 

 ever been successfully extracted from such cells. 



It is still possible that this may eventually be done but, al- 

 though indirect evidence like that of Denys, Longcope's observations 

 in leukemia, and the occasional increase of the alexic, powers q serum 



32 Moxter. Deutsche med. Woch., 1899, p. 687. 



33 Petterson. Centralbl f. Bakt., i, 39, 1905; 46, 1908. 



34 Schneider. Archiv f. Hyg., Vol. 70, 1909. 



35 Zinsser. Jour. Med. Res., Vol. 22, 1910. 



