36 



cup has moved away from the egg-shell and that a strauid of sorae 

 substance hy which It was prohably attached to the hotton of 

 the capsule is drawn out with it. Sometimes the nuclear cup 

 breaks loose from the strand and leaves it projecting through 

 the shell into the capsule (Pig. 100). In eggs taken from 

 the oviduct or from the pleopeds Just after spawning, large 

 numbers of sperm-vesicles are found sticking to the inside 

 of the shells after the nuclear cup has fallen off (Pig. 101). 

 It is very clear then that in most cases at least the nuclear 

 cup does not enter the egg* But, does it thus fall off from 

 the particular sperm that fertilizes the egg^ or only from 

 those which have failed to perform the work of fertilization? 

 This question can best be answered by a further study of the 

 events of fertilization. 



VIII. PERTILIZATIOBT. 



In eggs taken from the oviduct or just after leaving it, 

 many sperm-vesicles may be found lying on the edge of the 

 cytoplasm as shown in Pigs. 102 and 103, while one is found 

 down in the cytoplasm (Pigs. 104-108). Here it is evident 

 that the movement of the cytoplasm has carried the vesicle 

 below the surface. Before the sperm-vesicle enters there is 

 a layer of cytoplasm Just inside of the egg-shell. The rest 

 of the egg is filled with spherules of food material in the 

 interspaces of which the cytoplasm extends from the peripheral 

 layer, by fine strands, all through the egg. The fact, that 

 the sperules of food move apart and a small mass of cytoplasm 



