1880.] 



in the common Foivl and in the Rabbit. 



239 



germinal vesicles were observed in close contiguity. They were of 

 unequal size, and each had a relatively large macula. In another, 

 a figure of which is given (fig. 8), there are also two vesicles, but 

 one of these is evidently in process of disappearance, for the mem- 

 brane has become absorbed and the contents of the vesicle, including 

 the macula, are becoming assimilated in appearance to the vitellus. 



Yolk. — In all the ova the yolk seems composed of a network of 

 closely interlacing filaments ( 3 ). The network may be coarser or finer ; 

 it is very fine indeed in the peripheral layers of the largest ova (those 

 above a millimetre in diameter) which generally have a finely granular 

 aspect (fig. 10, I, II) ; coarser in the smaller ova and in the central 

 parts of the larger, but in the latter the coarse appearance of the net- 

 work seems chiefly due to the accumulation here of the large spherical 

 yolk globules, which being left clear in the sections, give a reticulated 

 appearance to the substance in which they are imbedded. In the 

 smallest ova there is nothing but clear fluid in the meshes of the net- 

 work, which is comparatively open. But in almost all there are con- 

 densations of the network (fig.6, c,) to be seen, in which the filaments are 

 far more closely interlaced, the appearance presented being very like that 

 which might be produced by gathering up a net made of string into a 

 bunch at one part. The filaments of the vitelline substance are but 

 slightly stained with logwood, but since they are more closely placed 

 in the condensations here spoken of, these are more stained than the 

 rest of the yolk. Eventually as the ova increase in size the conden- 

 sations seem to become more numerous (fig. 5), and to spread, and 

 the vitelline network to become eventually closer and finer everywhere, 

 but especially at the periphery of the ovum and around the germinal 

 vesicle, the deposit of the yolk globules producing, as we have seen, a 

 coarser appearance in the more central parts. 



Other condensations (fig. 9) of vitelline substance occur in some ova 

 which are more circumscribed and definite than those just mentioned. 

 They are nucleus-like, spheroidal patches, which stain deeply with 

 magenta, less deeply with logwood, are homogeneous in appearance, and 

 are usually encircled with a corona of short, straight, radiating fila- 

 ments, which do not interlace with one another like those of the 

 vitelline substance around, but may however (I am not sure of this) be 

 continued into the vitelline network of these pseudo-nuclei, as I will 

 term the structures in question. There may be one, two, or even a 

 greater number in the vitellus of the same ovum, with the germinal 

 vesicle of which they have no apparent connexion. 



I am unable to conjecture the meaning of these pseudo-nuclei, or to 

 decide whether they are of the same nature as the " yolk-nuclei " which 

 have been mentioned by several observers as occurring in the ova of 

 fish and Amphibia ( 4 ) . 



In the largest ova the yolk exhibits several distinct layers which 



