418 FRANKLIN P. MALL 



question has been tested recently in Arbacia by F. R. Lillie,i^ 

 who makes the following interesting statements: The sperma- 

 tozoa are absolutely immobile while they are in the body of the 

 male, but become intensely active when suspended in sea-water. 

 They then become relatively inactive, but can be restored again 

 by the addition of fresh sea-water. When greatly diluted they 

 lose their fertilizing power completely in about an hour, and 

 when diluted by 250,000 times their volume in water this power 

 lasts but a few minutes. The loss of fertilizing power cannot be 

 due to a loss of motility, for long after the former occurs no 

 loss of vitality or motion is observed. In man the secretion 

 of the prostate gland maintains the motility of spermatozoa 

 much more effectively than does normal saline solution, and it is 

 said that the secretions of the mucous membrane of the uterus 

 and tubes have a similar influence. Thus it would seem that 

 when motility is accelerated it does not indicate that the power 

 to fertilize is prolonged, as asserted by Waldeyer. Lillie's 

 experiments certainly do not favor such a view, and Bryce and 

 Teacher infer the same when they state that were the spermatozoa 

 to retain for a long time their power of fertilization, no ovum 

 could escape fertilization. 



For the sake of argument Bryce and Teacher deduct 24 hours 

 from the copulation age of their specimen (16^ days) .and esti- 

 mate that it would have been 15| days old had it lived up to the 

 time of abortion. This seems to me to be reasonable, as are the 

 other statements in their admirable paper. 



In view of the difference between the fertilization power of 

 spermatozoa and their motility, as expressed in Lillie's report, 

 we may admit with considerable safety that the fertilization 

 power of sperm is of shorter duration than is the power on the 

 part of the egg to be fertilized. Furthermore, the theory that a 

 fruitful copulation should be accompanied by ovulation at about 

 the same time is a necessary one, in order to account for all of the 

 combinations which are encountered in human beings. Nor is 

 the assumption of Bryce and Teacher of an oestrus following 



1^ Lillie, F. R. 1915 Analysis of variation in the fertilizing power of sperm 

 suspensions of Arbacia. Biol. Bull., vol. 28. 



