II. CYTOTOXINS. 



Cytotoxins Definition Leucotoxin Nature of the 

 Cytotoxin Anti-cytotoxin. After it had been found 

 that the injection of an animal with red blood- 

 cells of another animal was followed by the produc- 

 tion of definite, specific reaction substances, investi- 

 gators experimented to see whether this was also 

 the case if other animal cells were used. Injections 

 were made with white blood-cells, spermatozoa of 

 other animals, etc., and there resulted a series of 

 reaction substances, entirely analogous to the hag- 

 molysins, which were specific for the cells used for 

 injection. These sera Metchnikoff calls cytotoxins. 

 After Delezenne had published a short article on a 

 serum haemolytic for white blood-cells, Metchnikoff 

 undertook a study of the substances produced in 

 sera of animals treated with leucocytes of another 

 species. He injected guinea-pigs with the mesen- 

 teric glands and bone marrow of a rabbit. He 

 also injected for several weeks half an Aselli's pan- 

 creas at a time, at intervals of four days. If he 

 withdrew serum from such a guinea-pig he found 

 this to be intensely solvent for white blood-cells of 

 a rabbit. He called this serum leucotoxin. This 



59 



