656 STUDIES IN GENERAL PHYSIOLOGY 
sea-water might increase the motility or fertilizing power of 
the spermatozoa. The contrary is, however, true. The 
eggs of the same female were divided into two lots. The 
one was put into normal sea-water, the other was exposed for. 
fifty minutes to a mixture of 70 c.c. sea-water+ 30 c.c. 24n 
MgCl,. At about the same time the sperm of one male was 
distributed into two solutions of exactly the same character. 
After fifty minutes the eggs that had been in normal sea- 
water were divided into three portions. To the first portion 
was added sperm from the normal sea-water; to the second 
was added sperm that had been for fifty minutes in a mix- 
ture of 30 c.c. 24n MgCl, + 70 ¢.c. sea-water. To the third 
portion no sperm was added; it was intended to serve as 
control material. The result was as striking as could be 
desired. While the eggs to which the sperm from the nor- 
mal sea-water had been added developed without exception 
into trochophcres, not one egg developed in lot 2, to which 
the MgCl, sperm had been added. The control eggs remained 
likewise undeveloped. 
A number of the unfertilized eggs that had been in the 
MgCl, for fifty minutes reached the trochophore stage. 
This experiment proves conclusively that the MgCl, solu- 
tion annihilates or certainly diminishes the fertilizing power 
of spermatozoa. Ina previous series of experiments I had been 
able to show that the same is true for the eggs of sea-urchins. 
In addition I convinced myself through microscopic ex- 
aminations that the females used were not hermaphroditic. 
III. THE SPECIFIC EFFECT OF K IONS ON THE DEVELOPMENT 
OF THE UNFERTILIZED EGGS OF CHETOPTERUS 
The preceding experiments seemed to indicate that KCl 
has a specific effect upon the development of the unfertilized 
eggs of Chetopterus. Mead had already found’ that if 4 per 
1MEAD, Biological Lectures, Woods Hole, 1898 (Boston: Ginn & Co.). 
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