666 STUDIES IN GENERAL PHYSIOLOGY 



Twentieth series. The following solutions were used: 



(1) 100 c.c. sea-water + 2 c.c. -^n XaHO 



(2) 100 +2 " KHO 



(3) 96 +4 \n Na 2 CO 3 



(4) 100 +2 iVwHCl 



(5) 100 +3 " 



(6) Normal sea-water (control) 



The eggs of one female were distributed in these solu- 

 tions. One portion of the eggs was taken out of these solu- 

 tions and put back into normal sea-water ; the others remained 

 permanently in these solutions. Twenty-four hours later 

 the results appeared to be as follows: Of the eggs that had 

 remained in the solutions for twenty-four hours, those in 

 solutions 2 and 4 had well-developed trochophores that swam 

 about. In solution 1 several eggs seemed to have developed, 

 but I was unable to find one swimming or with cilia. Those 

 in the other solutions were undeveloped. The eggs that had 

 been in solutions 2 and 4 for only five to ten minutes had a 

 few trochophores; the others were undeveloped. 



It is evident that KHO is more effective than NaHO, and 

 it is natural that the effect of the K ions should have been 

 added to the effect of the HO ions. But the fact is very 

 striking that the addition of a small amount of HC1 to the 

 sea-water caused the parthenogenetic development of the 

 Chsetopterus eggs. 



Twenty-first series. The unfertilized eggs of a Cheetop- 

 terus were distributed in the following solutions: 



(1) 100 c.c. sea-water + 1 c.c. -fan HC1 



(2) 100 +2 



(3) 100 +3 



(4) Normal sea-water (control) 



One portion of eggs remained in the solutions five minutes, 

 the others permanently. The eggs that were taken from the 

 solutions after five minutes were undeveloped, with the 



