616 STUDIES IN GENERAL PHYSIOLOGY 
the spermatozoa lose their power of fertilizing eggs in a very 
short time (in about five hours). But that it was absolutely 
excluded is proven by the following facts: 
1. None of the unfertilized eggs kept in normal sea-water 
developed or formed a membrane. J examined millions of 
eggs in each experiment. Not one was found that was fer- 
tilized. The sea-water used in this case was the same as 
that used for the unfertilized eggs that did develop. If the 
sea-water had contained spermatozoa, the unfertilized eggs 
kept in normal sea-water all the time should have been fer- 
tilized. 
2. None of the eggs which developed after treatment 
with MgCl, solution ever had amembrane. Fertilized eggs 
which were put immediately after fertilization into a mixture 
of equal parts of %,9 n MgCl, and sea-water and kept there 
for two hours did not lose their membrane. In the ninth 
series I made the following control experiments: Unfertilized 
eggs that had been in the above-mentioned #9 n MgCl, solu- 
tion for two hours were put into normal sea-water to which 
fresh sperm was added. In this case a number of eggs 
formed membranes. 
3. No blastula originated from an egg that had been kept 
for some time in one of the following solutions: 
(1) 100 cc. 4°" MgCl, 
(2) 30cec.22n “ -+ 70 c.c. sea-water 
(8) 40 “© “ +69 « 
(4) 100 c.c. sea-water + 33 gr. (wet) MgCl, 
and the solutions mentioned in chap. iii. Yet eggs of the 
same female that had been kept for some time in a mixture 
of 50 or 60c.c. 2°n MgCl, and 50 or 40¢.c. of sea-water 
developed into blastule or plutei. This happened in spite 
of the fact that the vitality of the latter eggs had suffered 
more than that of those in the above-mentioned solutions 
with more sea-water and less MgCl,. Moreover the water 
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