376 



OTTO GLASER. 



Such experiments therefore are not capable of deciding whether 

 more or less soluble substance is secreted at fertilization than 

 before. That no agglutinin is secreted after fertilization is 

 complete, has been demonstrated by Lillie's ('i3 2 ) later work. 



The second possibility, that of utilizing the xanthoproteic test 

 suggested itself, for in case the yellow color were not due to 

 traces of dissolved jelly, it might increase as the result of fer- 

 tilization. As a matter of fact the yellow color gotten from sea- 

 water over eggs inseminated as above is deeper than that given 

 by an equal quantity of sterile water exposed to an equal quantity 

 of unfertilized eggs for the same length of time. This was con- 

 sidered a promising result until it was found that the addition 

 of even a small quantity of sperm increases the density of the 

 color to a marked degree. 



A third test however gave comparative results which are not 

 open to this difficulty. In these experiments I made use of the 

 fact that the unfertilized eggs of Arbacia discolor the sea-water. 

 Three sets of observations were made. In each of these I c.c. 

 of an egg-suspension of given concentration in which the ova were 

 uniformly distributed, was added to each of three tubes, one of 

 which contained 5 c.c. of sterile sea-water, the second 5 c.c. of 

 sea-water infected with just enough spermatozoa to be very faintly 

 opalescent, whereas the third contained 5 c.c. of "double" 

 sea-water, i. e., sea-water which had been boiled down to half its 

 original volume. Color tests were made in the usual way, and 

 the discoloration produced by the unfertilized eggs in a given 

 time was taken as unity. On this basis the following results 

 were obtained in an experiment exactly representative of the 

 others : 



ABC 



The extra c.c. of eggs was added at 9.56 to see whether the first 

 difference between A and B could be the result of either the slight 



