276 ANIMAL AGGREGATIONS 



Apparently the sperm most severely affected give the better re- 

 sults in fertilization. The explanation of this paradoxical situation 

 is that CO2 determines a crisis. In the former case, the fertilization 

 occurred during the crisis with abnormal results; in the latter case, 

 fertilization took place after the crisis was over, and the results 

 were normal. 



By a longer exposure of 20 to 60 minutes the contrast between 

 concentrated and dilute suspensions is reversed. The concentrated 

 recover gradually and in proportion give normal development, while 

 the dilute sperm suspensions lose fertilizing power more and more. 

 The same results are obtained with one-half the dose of CO2. It is 

 scarcely possible even to suggest more rapid exhaustion of toxic 

 substance as the cause for the protective effect of numbers in this 

 case, since the CO2 is kept constant. Obviously Cohn's explanation 

 that the more concentrated sperm suspensions survive the longer 

 because of the greater CO2 tension which, by inhibiting activity, 

 promotes functional longevity, does not represent the whole story 

 of the protective action of the mass of spermatozoa, however true 

 it may be under many conditions. 



BIOELECTRICAL EXPLANATION OF MASS PROTECTION 



Again Drzewina and Bohn (1926) call attention to their experi- 

 ence that the more concentrated suspensions of sperm resist a raised 

 temperature better than the more dilute (see Young, 1929, on mam- 

 malian sperm). Also, with low temperature (1° C), if one compares 

 the effect on i/ioo or on 1/1,000 sperm, the cold activates the first 

 and inhibits the second, as if there were a change in the sign of the 

 reaction with the change in mass. Drzewina and Bohn report simi- 

 lar effects from darkening of sea-urchin sperm. They are particu- 

 larly interested in this protection furnished by the more concen- 

 trated masses of sperm, not only because of the similarities to their 

 observations on mass relations with various animals previously 

 cited, but the more so because they believe that the spermatozoa are 

 the bearers of electrical charges, which are not only associated with 

 the fertilization phenomena but are also concerned with the problem 

 of mass physiology of spermatozoa with which we are dealing here. 



