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 larve, 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 larve. The control eggs were undeveloped, 
save afew that had begun to segment. 
While a stay of thirty minutes in a mixture of 1 c.c. 24 
KCI + 99 ¢.c. sea-water suffices to cause the eggs to develop 
parthenogenetically, a stay of thirty hours in a solution of 
$cc. 24n KCl+ 994 c.c. sea-water remains without any 
effect. This may mean that a minimal quantity of K or KCl 
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 KCl 
due to the K ions or to the KCl molecules? The unfertil- 
ized eggs of one female were distributed into the following 
solutions: 
(ly lee. 23n KBr +97 c.c. sea-water 
(2) 2 “c “ +98 “ 
(3) 1 “ KNO; +99 “ 
(4) 2 “cc “cc +98 “ 
(5) 8 1.2nK.,80,+ 97 a 
(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 larve, the others remained undeveloped. This 
experiment proves that the K ions and not the KCl mole- 
cules produce the parthenogenetic development of the eggs 
of Cheetopterus. 
Conclusions.—These experiments confirm the conclusion 
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