loo PROBLEMS OF FERTILIZATION 



spermatozoa show no movement, and it is not until a 

 dilution of o . 33 per cent is reached that normal activity 

 is possible. Arbacia sperm exhibits traces of movement 

 at 2.5 per cent and Chaetopterus at over 20 per cent. 

 There is thus considerable variation in this respect 

 (Lillie, 1913). 



Acids decrease the activity of spermatozoa up to 

 complete paralysis, and at higher concentrations cause 

 death. Alkalies have in general the reverse action, 

 increasing activity up to the lethal point. The death 

 phenomena of sperm suspensions under acids and alka- 

 lies exhibit a striking difference in gross appearance, 

 the acid-killed sperm suspension remaining in a condi- 

 tion of dispersal, whereas in the alkali- (KOH or 

 NaOH) killed sperm suspensions the spermatozoa are 

 fused in strands which tend to anastomose; a similar 

 gross effect upon sperm suspensions is also produced by 

 the salts of trivalent metals (Gray, 1915). 



The degree of activity of spermatozoa is a function 

 of the H ion concentration of the medium, other things 

 being equal. Kolliker (1856), Giinther (1907), Gray 

 (1915), and Cohn (1918) have all recorded similar obser- 

 vations. It is important to note a fact emphasized by 

 Gray that spermatozoa inactivated by acid can be 

 reactivated by the addition of alkali if the concentra- 

 tion of acid used in the experiment has not been too 

 great; the inactivation and agglutination produced by 

 excess of alkali, on the other hand, is irreversible. 



Cohn (1918) has shown that the inactivation by H 

 ions has very important consequences for the func- 

 tioning of the spermatozoa, because they are constantly 

 giving off C0 2 into the medium. If the sperm sus- 



