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 sories. Unfertilized eggs were put 

 into a solution of 50 c.c. 2 / n MgCl 2 + 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 2 solu- 

 tion reached the blastula stage. Hence the treatment with 

 MgCl% diminishes the power of development of eggs, but 

 does not increase it. 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. 1 



Morgan repeated my experiments, obtaining the same result. 2 

 Norman tried the effects of a slight increase of MgCl 3 upon 

 spermatozoa. 3 I repeat his statement: 



I put sperm at 8:30 into MgCl 2 solution 2| gr. to 100 c.c. 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 LOEB, Journal of Morphology, Vol. VII (1892), p. 253. 



2 MORGAN, Anatomischer Anzeigcr, Vol. IX (1894), p. 141. 



3 NORMAN, Archivfur Entwickelungsmechanik, Vol. Ill (1896), p. 106. 



