ARTIFICIAL PARTHENOGENESIS IN ANNELIDS 661 
(1) 5ec¢. 24m KCl + 95 cc. distilled water 
(2) 10 “ “ + 90 [73 iT4 
(8) 15 “ “ + 85 “ we 
(4) Normal sea-water (control) 
The eggs were left in these solutions seven minutes and 
were then put back into sterilized sea-water. The next 
morning about 1 per cent. of the eggs that had been in 
solution 1 were swimming about. The eggs that had been 
in solution 2 had practically all reached the larva stage, 
although not all of them were swimming. The eggs that 
had been in the third solution contained swimming larve, 
but fewer than the other two lots. The control eggs had 
remained absolutely unsegmented during the first nine to 
ten hours. They showed, however, a beginning of segmen- 
tation (2-3 cells) the next morning. 
Sixteenth series.— There was no longer any doubt 
concerning the fact that KCl is able to bring about the 
development of the unfertilized eggs of Chetopterus. It 
was, moreover, apparent from experiment 10 that if only 
dec. 24n KCl is added to 994c.c. of sea-water, no trocho- 
phores are formed. It was natural to conclude from this 
that a certain minimal amount of K ions must enter the egg 
in order to make it reach the trochophore stage. In order to 
decide this the following experiment was tried. The eggs 
of one female were put into a solution of 2c.c.24n KCl+ 
98¢.c sea-water, and put back into normal sea-water at 
various intervals, viz., after one minute, three minutes, seven 
minutes, nine minutes, thirteen minutes, twenty minutes, 
forty minutes. The results of this experiment were as defi- 
nite as could be desired. 
After from nine to ten hours the eggs of the first lot (that 
had been in the KCl sea-water for one minute only) were 
absolutely unsegmented. In the second lot (three miautes) 
a few eggs were segmented, but no trochophore was formed. 
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