MUSEUM OF COMPARATIVE ZOOLOGY, 



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tivo force, since they swarm about it ; and great numbers become 

 attached to it, as well as to the wall of the branchial sac in its vicin- 

 ity, as shown in Figs. 9, 10, 11, and 12. A few of them penetrate 

 the gubernaculum, and work their way up towards the egg (Fig. 10) ; 

 and, although none were actually seen which had travelled over much 

 more than half the distance between the tip of the gubernaculum and 

 the egg, there seems to be no obstacle in their way, and they prob- 



-4. 



Successive stages of segmentation : c, branchial tunic of male : A, cavity of branchial sac of male; 

 i, sinus system of male ; 4, yolk ; S, food-yolk ; 9, germ-yolk ; 10, orifice of brood-sac ; 11, 

 invagination orifice. 



ably reach the yolk ; but the subsequent changes follow so rapidly 

 that no egg was found showing them so situated. 



Immediately after impregnation the germinative vesicle disappears, 

 but as the actual process was not observed, nothing can be stated 

 as to the manner in which the disappearance takes place. Soon 

 after this is lost sight of, the gubernaculum becomes irregularly 

 swollen and shortened, as shown in Figs. 11 and 12, and the yolk 



