608 STUDIES IN GENERAL PHYSIOLOGY 
poisonous effect of the Mg ions, and it seemed possible to me 
that a decrease in the amount of MgCl, and a slight increase 
in the amount of sea-water might allow the eggs to reach 
the pluteus stage. The eggs of two females were distributed 
in the following solution: 
(1) 60 cc. 4° n MgCl, + 40 c.c. sea-water 
(2) 50 cc. fe +50 eS 
(83) Normal sea-water 
The eggs were brought back into normal sea-water after 
one hour and five minutes, one hour and thirty minutes, and 
i hb > 5 | ‘ 
55 Z: 2.04 2:06 
3 | C Sp ¢ 
2:07 2:09 ac 2:18 
one hour and forty minutes. Only the eggs of the last lot 
that had been in the solution one hour and forty minutes 
showed the beginning of a development. I believe that I 
took out the eggs too soon. In some cases such eggs are 
able to develop, but in others they are not, and I think it 
probable that if the eggs had been left a little longer in so- 
lution 1 or Z they would have developed further. I made 
some camera drawings of the way in which the eggs were 
segmented (Fig. 148). The successive stages of the segmen- 
tation of one and the same egg up to the six-cell stage 
were drawn. The reader will see from the drawings that the 
egg went within twenty minutes from practically an undivided 
FIG. 148 
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