618 STUDIES IN GENERAL PHYSIOLOGY 
fertilizing power of the spermatozoon. Both possibilities 
must, however, be discarded. As far as the liability of the 
egg to impregnation is concerned, I made the following 
experiments in the last series. Unfertilized eggs were put 
into a solution of 50 ec. 2°n MgCl, + 50 c.c. sea-water 
and left in this solution for two hours. They were then 
taken out and fertilized with fresh spermatozoa. At the 
same time another lot of the eggs of the same female which 
had been kept for two hours in normal sea-water were fer- 
tilized with sperm of the same male. Practically every egg 
of the latter lot developed into a blastula, while only about 
50 per cent. of those eggs that had been in the MgCl, solu- 
tion reached the blastula stage. Hence the treatment with 
MgCl, diminishes the power of development of eggs, but 
does not increase tt. As far as the spermatozoa are con- 
cerned, former experiments by Norman, Morgan, and myself 
showed that a slight increase in the concentration of the 
sea-water destroys the fertilizing power of spermatozoa very 
rapidly. In my experiments I added 2 gr. of NaCl to 100 
c.c. of sea-water. 
The spermatozoa which had been in this solution for only a few 
hours, when brought back into normal sea-water, fertilized only 
a thousandth part or less of the normal eggs, while the spermatozoa 
of the same animal which had remained in normal sea-water 
fertilized at the same time almost all the eggs.) 
Morgan repeated my experiments, obtaining the same result.’ 
Norman tried the effects of a slight increase of MgCl, upon 
spermatozoa.’ I repeat his statement: 
I put sperm at 8:30 into MgCl, solution 24 gr. to 100 ce. of 
sea-water. At 8:30 some of the sperm was mixed with normal 
unfertilized eggs, and within three minutes the eggs were fertilized. 
At 8:42 eggs and sperm were again mixed. In two minutes egg 
membranes began to become visible, showing normal fertilization, 
1 Logs, Journal of Morphology, Vol. VII (1892), p. 253. 
2 MorGAN, Anatomischer Anzeiger, Vol. IX (1894), p. 141. 
3 NoRMAN, Archiv fiir Entwickelungsmechanik, Vol. III (1896), p. 106. 
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