ARTIFICIAL PRopucTION OF NorMAL Larva 605 
about how long the eggs must remain in this solution. I 
now desired to verify these results and in addition find out 
accurately how far the proportions between sea-water and 
the 2° n MgCl, solution might vary without interfering with 
the results. The unfertilized eggs of one female were dis- 
tributed in the following solutions: _ 
(1) 60 cc. 4°20 MgCl, +40 c.c. sea-water 
(2) 30 « +70 “ 
(83) Normal sea-water 
At five different periods (one hour, one hour and forty 
minutes, one hour and fifty-five minutes, two hours and 
twenty minutes, two hours and forty-five minutes) portions 
of the eggs in solutions 1 and 2 were brought back into 
normal sea-water. After all that has been said, it seems 
superfluous to give all the details as explicitly as in the pre- 
ceding experiments, and I shall therefore confine myself to 
a description of the main results as they appeared next 
morning. The eggs in solution 3 (normal sea-water) had no 
membranes nor had any egg segmented. It is obvious that 
unfertilized eggs do not always undergo a beginning of seg- 
mentation in normal sea-water after twenty or twenty-four 
hours. Of the eggs that had been in solution 1 for one 
hour and fifty-five minutes, about 25 per cent. had developed 
into a blastula which swam about. About the same result 
was obtained in the lot that had been for two hours and 
twenty minutes in solution 1. The appearance of these 
blastulee was the same as in the previous experiments. Most 
of them were only fractions of one egg, and it was not 
uncommon to see four smaller blastulee swim together, each 
apparently having developed from one of the blastomeres of 
the four-cell stage. In the other lots which were taken from 
solution 1 a few blastulee were formed. The eggs that had 
been in this solution for one hour were practically all 
undivided, except that one in a thousand had segmented into 
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