1880.] On the Structure of the Immature Ovarian Ovum, Sfc. 237 



March 18, 1880. 



THE PRESIDENT in the Chair. 



The Presents received were laid on the table, and thanks ordered for 

 them. 



The following Papers were read: — 



I. " On the Structure of the Immature Ovarian Ovum in the 

 common Fowl and in the Rabbit. To which is appended 

 some Observations upon the Mode of Formation of the 

 Discus Proligerus in the Rabbit, and of the Ovarial Glands 

 or 'Egg-tubes' in the Dog." By E. A. Schafer, F.R.S. 

 Received March 3, 1880. 



[Plates 2, 3, 4.] 



The Ovarian Ovum of the Bird. 



In the ovary of a laying hen, Graafian follicles are to be found in 

 almost every stage of growth, and the fundamental parts — germinal 

 spot, germinal vesicle, yolk, and follicular epithelium — exhibit dif- 

 ferences both in relative size and in structure at various stages of 

 growth. I will proceed to consider the structure of each fundamental 

 part in detail, as it is presented in sections of the ovary prepared 

 after hardening in picric acid and alcohol, and stained with log- 

 wood or with magenta. 



Germinal Spot. — In larger ovarian ova, those which are already 

 •5 millim. and upwards in diameter, the germinal spot appears homo- 

 geneous and stains of a uniform dark colour with logwood (fig. 1). It 

 is either completely spherical in shape, or somewhat ovoid. In the latter 

 case it is very commonly eccentric and placed close to the wall of 

 the germinal vesicle, with which it may appear to be blended. When 

 spherical it is often situated near the centre of the vesicle ; and from 

 its periphery, in what may be considered a typical condition, filaments 

 of great tenuity radiate outwards to the wall of the vesicle, to the 

 inner surface of which they are again attached, and that so closely 

 that it frequently happens that when shrunken from the action of 

 reagents, the filaments may break in the middle rather than suffer 

 themselves to be dragged away from the wall (fig. 1, g). These radi- 

 ating filaments ramify and intercommunicate in such a way as to form 

 a delicate network (intra-nuclear network) which as we have seen 



