LEUCOCYTIC PRODUCTION OF ANTITOXIN. 321 



in typhoid. During the process of immunization 

 and at a time when amboceptors were absent from 

 the serum they could be demonstrated in the blood- 

 forming organs (spleen, lymph glands, bone-mar- 

 row) . Metchnikoff suggests that they may be pro- 

 duced in these organs by the microphages which 

 have wandered in after having englobed the micro- 

 organisms. In contrast to cytase the fixators read- 

 ily abandon the leucocytes which produced them 

 and become a constituent of the plasma. 



The leiicocytes have also been brought in rela- JJJJJJJ 

 tionship to antitoxic immunity and the formation Toxins. 

 of antitoxins. In experimental tetanus exudates 

 which are rich in leucocytes contain more toxin 

 than does a similar quantity of blood. That is to 

 say, the leucocytes have the power of absorbing 

 toxins, and it is held that the natural immunity 

 of the animal depends on the degree to which this 

 power is present. The immunity of the chicken 

 to tetanus depends not on non-susceptible nerve 

 cells nor on the presence of natural antitoxin, but 

 on the absorbing power of the leucocytes for the 

 toxin. Not only do leucocytes absorb toxins, but 

 it is held that they also are the producers of anti- 

 toxins. As compared with the side-chain theory, 

 it is a peculiarity of the view of Metchnikoff that 

 antitoxin does not represent a constituent of the 

 tissue cells, but rather the toxin itself, which has 

 been altered by leucocytic activity in a manner as 

 yet obscure. 



In passive antitoxic immunity the idea of a passive Anti- 

 chemical union between toxin and antitoxin does n *uy? Immu " 

 not meet with general acceptance among the up- 

 holders of the phagocytic theory. It is sometimes 



