244 L. V. HEILBRUNN. 



Time Eggs Remained Percentage of Eggs 



in Sea-water before Showing Membrane 



Treatment with Elevation. 



HgCh, Minutes. 



o o 



5 6J 



10 7 2 



15 I0 



20 10 



30 US 



40 13 



50 142 



60 17 



81 



103 . 



128 



158 16 



193 l8 i 



238 3oi 



268 21 



300 - 625 



345 -942 



Although the table is not as regular as might be wished, it 

 is clear that as the eggs lie in sea-water they become increasingly 

 susceptible to mercuric chloride. This fact is interesting for at 

 least two reasons. In the first place it apparently does not 

 harmonize very well with the fertilizin theory of fertilization as 

 developed by F. R. Lillie. 3 Aging of eggs, according to this 

 theory, involves a loss of fertilizin, a material which is regarded 

 as essential to fertilization, and yet in the experiment described 

 above, such aging favored a cortical change characteristic of 

 fertilization. But the case of mercuric chloride is certainly a 

 special one, and it is doubtful if any general conclusions for or 

 against the fertilizin theory can be derived from it. This will 

 be more obvious from the later discussion. 



Our main interest is elsewhere. Why do eggs after standing 

 in sea-water respond more readily to treatment with mercuric 

 chloride? Possibly in or around eggs fresh from the ovary there 

 is some substance present which exerts an interference. This 

 substance escapes on standing; it may be gaseous. On a priori 

 grounds one would suspect carbon dioxide. 



Experimental evidence favors this conjecture. When eggs 



