STUDIES IN THE PHYSIOLOGY OF SPERMATOZOA. 189 



In suspensions with the highest concentration of weak acids 

 the spermatozoa lived for the shortest time. For the higher the 

 concentration of weak acids the smaller the change in the hydro- 

 gen ion and carbon dioxide concentration of the suspensions due 

 to the carbon dioxide produced by the spermatozoa. Conse- 

 quently spermatozoa in more alkaline solutions, where they were 

 most active, lived for the shortest time. In order the better to 

 prevent spermatozoa from being inactive, a borate mixture that 

 was slightly more alkaline than sea water was employed in the 

 first three experiments reported (Experiments 205, 208, 209). 

 The hydrogen potential of the borate mixture is recorded in the 

 last column of Table VII. 



That even this slight change in the hydrogen potential of the 

 borate effects spermatozoa is demonstrated in Experiment 223 

 where slightly different mixtures of borates w r ere used in the same 

 concentration. It will be seen that spermatozoa in the suspen- 

 sion to which had been added the more alkaline mixture, lived 

 the shorter time. 



VI. THE EFFECT OF THE HYDROGEN ION CONCENTRATION OF 



THE SUSPENSION UPON THE ACTIVITY AND UPON THE 



LONGEVITY OF SPERMATOZOA. 



The activity of spermatozoa is a function of the hydrogen ion 

 concentration. Repeated observation has confirmed this rela- 

 tion. Since there is a definite relation between the activity 

 and the length of life of spermatozoa, the latter is also a func- 

 tion of the hydrogen ion concentration. The hydrogen ion 

 concentration of the ocean at Woods Hole, Massachusetts, 

 is about o.i X io~ 7 (Ph 7.95 to Ph 8.15). The weak acids 

 (Henderson. L. J., and Cohn, E. J., 1916) and the currents pre- 

 vent the hydrogen ion concentration of the ocean from appre- 

 ciably changing. In such a solution the length of life of sperma- 

 tozoa is short. 



Loeb has observed the simultaneous spawning of the sea ur- 

 chins (Strongylocentrotiis purpuratus) at the shore of Pacific 

 Grove. "At such spawning seasons the sea water becomes a 

 suspension of sperm" (Loeb, J., 1916, p. 94). It would be inter- 

 esting to know whether the hydrogen ion concentration of such 

 a suspension increases. 



