H. H. NEWMAN. 



peated and in this case the control showed two cleavages in 

 83 eggs while those treated with Na.,So 4 showed twenty normal 

 embryos in 95 eggs. 



Evidently, then, the antifertilization effect of the calcium ions 

 on the egg may be reversed by sodium sulphate. Probably the 

 CaCL, produces the gel condition in the egg membrane and the 

 Na 2 SO 4 redissolves the coagulum. 



In order to test the hypotheses that the calcium or magnesium 

 ions in sea water have the effect of slowly coagulating the mem- 

 brane of the egg and of thus rendering it impermeable to its own 

 sperm after a period of an hour or slightly more, the following 

 experiment was undertaken : 



Experiment VII. A lot of eggs were stripped into distilled 

 water, mixed thoroughly and then divided into five dishes con- 

 taining respectively 



A. Sea water. 



B. T " . KC1. 



C. T 'v ft. NaCl. 



D. Equal parts of B and C. 

 M Na 2 SO 4 . 



E. 



10 



After standing one and one-half hours a portion of the eggs 

 from each dish was transferred to sea water, washed and an 

 attempt made to fertilize, with the following result : 



After standing two and one-half hours another portion of the 

 eggs was transferred from the original five dishes, washed and 

 fertilized in sea water with the following result : 



