218 M. F. GUYER 



when observations were discontinued; in the serum of 32A2, 

 however, they were immobiUzed in a Httle over an hour; in the 

 serum of one of her young they remained active about thirty 

 hours; in the serum of the treated male they had ceased activity 

 by the end of forty-three minutes. The spermatozoa of the 

 sperm-treated male were also tried out in the various sera. In 

 his own serum they were immobilized in less than half an hour; 

 in the sensitized serum of female 32A2 most of them were immo- 

 bilized by the end of an hour, though a few were still moving 

 feebly two hours later, when observations were discontinued 

 for the day. Those placed in normal serum and in the serum of 

 the young of 32A2 still showed considerable motion at this time, 

 although their activity was noticeably more reduced in the 

 serum of the young one. Both lots had ceased to move by the 

 next morning, therefore the exact time at which each had become 

 inactive was not determined. 



The results of experiment 3 show that active spermatotoxins 

 can be built up in rabbits against the spermatozoa of rabbits. 

 Also, apparentlj^, male rabbits injected with rabbit spermatozoa 

 have their own spermatozoa greatly weakened. In this experi- 

 ment the serum of the male became more toxic than that of the 

 females, but it does not follow, of course, from a single experi- 

 ment, that this is the rule. The serum of a young rabbit three 

 days old, born of a sensitized mother, was toxic, but much less 

 so than that of its mother. 



Experiment 4 



The experiment was next made to determine whether or 

 not a given individual will form antibodies against its own sperma- 

 tozoa when these are introduced into the blood. On December 

 8th males 58 and 29A3 were bred to separate females and each 

 was then injected intravenously with his own semen. On 

 December 15th this was repeated with 58, but 29A3 seemed 

 unable to mate and he was abandoned. Male 53B2 was mated 

 instead (December 16th) and injected. On December 18th, 

 58 was mated again and injected as before with his own semen. 



