664 STUDIES IN GENERAL PHYSIOLOGY 



minutes showed the following condition the next morning: 

 Those that had been for thirty minutes in the first solution 

 had no trochophores ; only a few had begun to segment. 

 The eggs that had been taken out of solution 2 after thirty 

 minutes had formed many larvae, but fewer than the eggs 

 that had remained in the solution. Those that had been 

 taken out of solution 3 after thirty minutes had formed 

 many swimming larvse. The control eggs were undeveloped, 

 save a few that had begun to segment. 



While a stay of thirty minutes in a mixture of 1 c.c. 2-| 

 KC1 + 99 c.c. sea- water suffices to cause the eggs to develop 

 parthenogenetically, a stay of thirty hours in a solution of 

 ^ c.c. 2^w KC1 + 99^ c.c. sea-water remains without any 

 effect. This may mean that a minimal quantity of K or KC1 

 must enter the eggs in a certain minimal time or rather sud- 

 denly. It may, however, find a different explanation. 



Nineteenth series. Is the fertilizing power of the KC1 

 due to the K ions or to the KC1 molecules? The unfertil- 

 ized eggs of one female were distributed into the following 

 solutions : 



(1) 1 c.c. 2^n KBr + 97 c.c. sea-water 



(2) 2 " " +98 " 



(3) 1 " KNOs+99 



(4) 2 " " +98 " 



(5) 3 1.2nK 2 SO 4 +97 " 



(6) Normal sea-water (control) 



The eggs remained in these solutions thirty minutes, and 

 were then put back into normal sea- water. The eggs that 

 had been put in solutions 2, 4, and 5 formed a large number 

 of swimming larvae, .the others remained undeveloped. This 

 experiment proves that the K ions and not the KC1 mole- 

 cules produce the parthenogenetic development of the eggs 

 of Chaetopterus. 



Conclusions. These experiments confirm the conclusion 



