STUDIES ON CYTOLYSINS— SPERMATOTOXINS 223 



fluenced specifically in vivo by the spermatotoxic serum of their 

 own host. 



6. Since an animal can thus on occasion build antibodies 

 against its own tissues when these have become misplaced or 

 altered, and since antibodies can directly or indirectly affect 

 the germ-cells, it is reasonable to suppose that such influences 

 may be the source of certain germinal variations. 



