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. 2^n NaCl, they will not 

 develop into blastulse when put back into normal sea-water; 

 but if left for some time or permanently in such a solution, 

 a small number of blastulse may be formed. A number of 

 the unfertilized Cha3topterus eggs were left permanently in 

 solutions 1-6. The next morning the eggs that had been 

 left in solution 2 (1 KC1 + 99 c.c. sea- water) had swimming 

 trochophores. The eggs in solution 1 did not reach the 

 trochophore stage. In the other solutions 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) 1 c:c. 2Jn KC1+99 c.c. sea-water 



(2) 1J " + 98J 



(3) 2 " " +98 ' " 



(4) 10 " " +90 



(5) Normal sea-water (control) 



