ARTIFICIAL PRoDUCTION oF NorMAL Larva&é 607 
osmotic pressure was not sufficient. Moreover I wished 
once more to repeat the former experiments. The unfer- 
tilized eggs of one female were distributed in the following 
solutions ; 
(1) 60 cc. 44% MgCl, + 40 c.c. sea-water 
(2) 100 c.c. sea-water + 34 gr. (wet) MgCl, 
(3) 100 c.c. sea-water-+ 8 gr. (wet) MgCl, 
(4) Normal sea-water 
At various intervals a lot of the eggs were taken out of 
each of the four solutions and put into normal sea-water. 
The eggs that had been in solution 1 from one and one-half 
to two hours had developed into blastule the next norning. 
The number of blastule was comparatively larger than in 
any of my previous experiments. The eggs that had been 
in solutions 2 and 3 contained no blastule. Solution 2 is, by 
the way, the one Norman and Morgan had used in their ex- 
periments. In solution 4 no egg was even segmented the 
nextday. In none of the four solutions had any egg formed 
amembrane. These experiments show that the substitution 
of a number of Mg ions for one-half of the ions naturally 
contained in the sea-water is either necessary or more favor- 
able than the mere addition of Mg ions. This experiment 
explains why Morgan did not succeed in getting live larve, 
having treated the eggs with solution 2. But I intend to 
determine in my future experiments whether the addition 
of a little more than 34 gr. of MgCl, and a little less than 
8 gr. of the solution to 100 c.c. of sea-water may not give 
more favorable results. 
Fifth series.—I next wished to try whether it would not 
be possible to carry the artificial development of the unfer- 
tilized egg one step farther. The blastule thus far obtained 
were by no means healthy, and although some of them looked 
normal, they died before they had time to reach the pluteus 
stage. This latter result I was inclined to ascribe to the 
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