CYTOTOXINS. 6 1 



destroys the spermatozoa of the animals whose 

 product was injected. This cytotoxin was named 

 spermotoxin. If animals are treated with spermato- 

 zoa there is produced a serum which is not only a 

 spermotoxin, but which is also haemolytic for the 

 red cells of that animal. This was demonstrated 

 by Metchnikoff and Moxter, and has already been 

 referred to in discussing haemolysins. If, for ex- 

 ample, we inject the spermatozoa of sheep into 

 rabbits, we shall obtain a serum that is spermo- 

 toxic for sheep, as well as haemolytic for sheep 

 red cells. This is the case even when the greatest 

 care is exercised to exclude every trace of blood 

 in obtaining and injecting the spermatozoa. The 

 haemolysin, however, differs somewhat from that 

 obtained by injecting sheep red cells, and its pro- 

 duction is not hard to explain if we hold fast to the 

 side-chain theory. We assume that these sperma- 

 tozoa possess certain receptors in common with the 

 red blood-cells of the same animal. 



Anti-spermotoxin Auto-spermotoxin. By treating 

 an animal with its spermotoxin we can produce 

 an anti-spermotoxin which will inhibit the action 

 of the former. Metalnikoff, a pupil of Metchnikoff, 

 has demonstrated the occurrence of auto-spermo- 

 toxin. This, however, is only of scientific interest, 

 and I mention it here only for the sake of com- 

 pleteness. 



Cytotoxin for Epithelium. v. Dungern has pro- 

 duced an anti-epithelial serum by treating animals 



