658 STUDIES IN GENERAL PHYSIOLOGY 
been in solution 1 reached the trochophore stage. None of 
the eggs that had been only five minutes in the second solu- 
tion reached the trochophore stage. But the lot of eggs that 
had remained one hour in the second solution yielded a small 
number of swimming trochophores. The eggs that had 
been in solutions 3 and 4 differed widely from the preceding 
lots. They were teeming with swimming trochophores, those 
that had been in these solutions five minutes as well as those 
that had been in the solutions one hour. 
The control eggs and the eggs of lots 5 and 6 did not 
develop, although a number went through the first stages of 
segmentation. 
I had observed in my former experiments that the eggs 
of sea-urchins can develop parthenogenetically if left per- 
manently in sea-water whose concentration is raised but 
little. If the eggs of sea-urchins are put for two hours into 
a mixture of 92 c.c. sea-water + 8 c.c. 24” NaCl, they will not 
develop into blastule when put back into normal sea-water; 
but if left for some time or permanently in such a solution, 
a small number of blastule may be formed. A number of 
the unfertilized Chetopterus eggs were left permanently in 
solutions 1-6. The next morning the eggs that had been 
left in solution 2 (1 KCl + 99 cc. sea-water) had swimming 
trochophores. The eggs in solution 1 did not reach the 
trochophore stage. Intheothersolutions everything was dead. 
Eleventh series.—This series was practically a repetition 
of the preceding one, with the exception that the eggs 
remained from twenty to thirty minutes in the solutions, 
which were as follows: 
(1) lee. 24% KC1+99 c.c. sea-water 
(2) 14 “ “co + 984 “ 
(8) 2 “cc “ + 98 “ 
(4) 10 iT4 ce + 90 “ce 
(5) Normal sea-water (control) 
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