MASS PHYSIOLOGY OF SPERMATOZOA 



275 



were emitted which, when the sperm are numerous enough or when 

 the volume of Hquid is small enough, is sufficient to protect the 

 group. This action is regarded as being similar to that obtaining 

 when Procerodes are isolated into fresh water in which other organ- 

 isms have lived and died. This is Drzewina and Bohn's hypothesis 

 of the production of an autoprotective substance applied here to 



TABLE XXXI 



Effect of Dilution of Sperm Suspension in Three Different Media 

 (Data from Drzewina and Bohn) 



* It is noted here that in weak doses and certain concentrations of sperm KCl increases survival of sperm. 



spermatozoa, and adds the j&fth explanation of the greater longevity 

 of relatively heavy sperm suspensions. 



The same workers (1926(1) reinvestigated the effect of carbon 

 dioxide upon the longevity of spermatozoa. They exposed sperm 

 suspensions of different dilutions, from 100 to 5,000 times diluted, to 

 sea-water kept saturated with CO2, with results which may be sum- 

 marized as follows: 



Diluted i/ioo No paralysis; sperm immediately gather around 



the eggs, but no fertilization membrane is formed. 



Segmentation is irregular, and larvae cytolyze 



easily. 

 More dilute Paralyzed ^ hour, but then recover and fertilize 



with normal membranes and development. 



