THE EGG 25 



around the stalk of the capsule, seemed to exert some pressure 

 on it, in other cases the ruptured capsule still partly enclosed 

 the egg which projected from the opening; in others finally 

 the empty capsule had just deposited the egg in the entrance of 

 the oviduct." 



The existence of double-yolked eggs renders it probable that 

 the oviduct can pick up eggs that have escaped into the body- 

 cavity. But in some cases ova that escape into the body-cavity 

 undergo resorption there. 



Immediately after the ovum is received by the oviduct it 

 appears to become softer and more flexible (Coste). The upper- 

 most portion of the oviduct then secretes a special layer of albu- 

 men which adheres closely to the vitelline membrane and is 

 prolonged in two strands, one extending up and the other down 

 the oviduct; these strands become the chalazse; the layer to which 

 they are attached may, therefore, be called the chalaziferous 

 layer (Coste) of the albumen. The ovum then passes down the 

 oviduct, rotating on the chalazal axis, and thus describing a 

 spiral path; the albumen which is secreted abundantly. in advance 

 of the ovum is therefore wrapped around the chalaziferous layer 

 and chalazae in successive spiral layers and the chalazse are re- 

 volved in spiral turns. The main factor in propulsion of the 

 ovum along the oviduct appears to be the peristaltic movements 

 of the latter; it is probable that the cilia which line the cavity 

 have something to do with the rotation of the ovum on its chalazal 

 axis. 



The line joining the attachments of the chalazse is at right 

 angles to the main axis of the ovum (that passing through the 

 germinal disc); it is obvious, therefore, that there must be some 

 antecedent condition that determines the position of the ovum 

 in the oviduct; probably the position of the ovum in the follicle, 

 i.e., the relation of the germinal disc to the stigma, for the fol- 

 licular orientation is apparently preserved in the oviduct. The 

 question is of considerable importance because, as we shall see, the 

 axis of the embryo is later bisected by a plane passing through 

 the chalazae, and is therefore certainly determined at the time 

 that the chalazse are formed. Is the embryonic axis determined 

 before or after ovulation, and how is it determined in either event? 

 This question, to which there is at present no answer, furnishes 

 an interesting problem for investigation. 



