264 



LEIGH HOADLEY. 



Table lib. 



Viability test. 1 : 150,000 ZnCh. July 5, 1922. Eggs and sperm fresh. 

 Insemination 1 : 25 : 7.5. 9 A. Exp. 2 : 45 P.M. Temp. 20 C. 



of NaOH, the sperm could be reactivated. Because of this, I 

 made a few additional experiments on the sperm of Arbacia with 

 LaCl 3 solutions. In the case of the immediate insemination in 

 the lanthanum chloride solution, I found that, at a concentration 

 of N/4.,090 or 1 : 50,000, membranes are not raised. I then 

 made up a thick sperm suspension by adding a number of drops 

 of dry sperm to 7.5 c.c. of the LaCl 3 solution and observed that 

 the sperm clumped and that their activity was much inhibited. 

 The sperm in this solution were, however, reactivated by the 

 addition of a drop of iV/500 NaOH. I then made a similar 

 suspension and added one drop of concentrated egg sea-water. 

 The sperm immediately became very active and gave a very 

 definite agglutination reaction. 



After the membrane-inhibitory concentration had been estab- 

 lished as 1 : 50,000, this solution was made up replacing the 

 normal sea-water with concentrated egg sea- water, i.e., egg sea- 

 water of high agglutinating power. When eggs were inseminated 

 in such a solution, the percentage of membrane formation rose 

 from o per cent, to 64 per cent, to 72 per cent. It may thus be 

 seen that egg sea-water has a great protective action in lan- 

 thanum-inhibition. 



The viability test of the normally inseminated eggs in I : 50,000 

 LaCl 3 solution showed that this concentration is very slightly 

 toxic to cleavage. As will be recalled, a cleavage-toxic concen- 

 tration could not be determined because of the great amount 

 of precipitation. 





