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. I 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 2 solution ever had a membrane. Fertilized eggs 

 which were put immediately after fertilization into a mixture 

 of equal parts of 2 n MgCl 3 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 2 g- n Mg01 3 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) lOOc.c. VnMgClo 



(2) 30c.c. 3 n + 70 c.c. sea-water 



(3) 40 " +60 



(4) 100 c.c. sea-water + 3i gr. (wet) MgCl 2 



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 60 c.c. 2 ttMgCl 2 and 50 or 40 c.c. of sea-water 

 developed into blastulse 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 2 . Moreover the water 



