214 M. F. GUYER 



discontinued. The serum of the third fowl (May 26th) immo- 

 bilized normal spermatozoa in from five to seven minutes. In 

 a 2-to-l dilution of the sensitized serum with normal saline 

 solution normal spermatozoa were immobihzed in thirty minutes, 

 while in a similar dilution of normal serum they were still active 

 at the end of forty minutes. The undiluted serum of the fourth 

 sensitized fowl immobilized normal rabbit spermatozoa in ten 

 minutes; normal fowl-serum did the same in thirteen minutes. 

 Sensitized senmi of the fourth fowl, diluted with an equal volume 

 of normal saline solution, immobilized normal rabbit spermato- 

 zoa in ten minutes; sunilarly diluted jiormal fowl serum did so in 

 twenty-three minutes. Diluted with 3 parts of normal saline 

 solution, this same sensitized serum immobilized normal rabbit 

 spermatozoa in ten minutes; normal fowl-serum similarly diluted 

 did so in thirty minutes. One part of the sensitized serum and 

 5 parts of normal saline solution produced immobility in such 

 spermatozoa in seventeen minutes; in a similar dilution of the 

 normal serum, some activity was observable nearly two hours 

 later, when observations were discontinued. 



In the meantime tests were also being made on the spermatozoa 

 of a guinea-pig with the serum from the fourth fowl sensitized 

 against the spermatozoa of the rabbit. This serum diluted with 

 5 volumes of normal saline solution immobilized the spermatozoa 

 of the guinea-pig in twenty-five minutes; in normal fowl serum 

 similarly diluted such spermatozoa were still active three hours 

 later, when observations were discontinued. In a mixture of 

 1 part of the sensitized serum to 10 parts of normal saline solu- 

 tion, the spermatozoa of the guinea-pig were immobilized in a 

 little over thirty minutes, while in the control of normal fowl 

 serum similarly diluted they were still active three hours later. 



Nearly a year later, April 5, 1921, males 25 and 83 were 

 again tested for fertilitj^ Male 25 had many active spermatozoa 

 in his semen, although the total number was below normal. A 

 mating made with him on this date yielded six young. The 

 semen of male 83, however, when examined microscopically, 

 appeared to be free from spermatozoa and the female bred to him 

 bore no young. 



