COPPER, ENZYMES, AND FERTILIZATION. 8 1 



is possible by microscopic examination in suspensions of india ink, 

 and, as a matter of fact, I never employed material unless the eggs 

 appeared uninjured, nor unless at least 90 per cent, failed to reveal 

 the jelly. However, it was impossible to offset the fact that equal 

 volumes of normal and dechorionized eggs can not contain equal 

 numbers. It is not surprising, therefore, that comparisons with 

 normal material should prove variable; nevertheless, in view of 

 my other experiments, I did not expect to encounter the irregu- 

 larities actually found. These were so great that the results are 

 best appreciated in the following form: 



Excess Copper Removed 



in 75 minutes 



from 10 cc. w/1460 Solution by 



.2 cc. Normal Eggs .2 cc. Dechorionized Eggs 



Lot A 23.3% 



Lot B 11.5% 



Lot C . . . .' 29.5% 



Lot D 4.0% 



Lot E 2.0% 



Lot F 8.3% 



Lot G 13.7% 



Lot H 54-o% 



Ratio . . . 5.7 : 1 



. This clearly does not indicate that dechorionized eggs remove no 

 copper from solution, but that normal eggs, on the average, re- 

 move more. If we neglect the numerical differences in equal vol- 

 umes of the two classes of eggs — a handicap distinctly against the 

 normal material — we can say that the copper profit of normal was 

 to that of dechorionized eggs at least as 5.7: 1. 



It follows that the chorion is heavily involved in the removal of 

 copper from solution. Yet the amounts taken up can not be deter- 

 mined even from my original values ; nor can these be used as a 

 basis for predicting the precise outcome of any particular competi- 

 tion for copper between normal and dechorionized eggs. Indeed, 

 the results, though valid enough, once more mask a fundamental 

 source of error. 



V. Irregularities in the Removal of Copper from 

 Solution. 

 The irregularities encountered were of several sorts. Equal 

 quantities of eggs, during equal exposures, did not invariably ap- 



