174 OVARY AND PAROVARIUM, BY W. WALDEYER. 



be allowed to stand for twenty-four hours, so that the debris of the 

 cells may settle to the bottom. The albuminous substance it holds 

 in solution consists, according to my investigation, exclusively of that 

 termed paralbumen by Scherer (123). 



In the discus proligerus, -which indeed only exists in the 

 Graafian follicles of Man and Mammals, we must distinguish 

 between the epithelium of the follicle and that belonging to 

 the ovum. The latter (fig. 191, /, and fig. 193, G a) forms an 

 uninterrupted circlet of columnar cells around the ovum, 

 arranged in the form of an epithelial investment to the 

 zona pellucida. In young follicles there is no internal cavity 

 containing fluid, the ovum with its single epithelial investment 

 completely filling up the space. Successive layers of epithelial 

 cells gradually appear, in which the ovum lies imbedded ; it is 

 only at a later period that a nearly semilunar space, filled 

 with fluid, occurs at a part remote from the ovum, and which 

 constitutes the first trace of the follicular cavity ; a large 

 collection of epithelial cells remains, surrounding the ovum, 

 and forming the rudiment of the discus proligerus. 



In regard to the position of the ovum in the follicle of the 

 Mammalian ovary, it may be mentioned that it does not by 

 any means appear to be constant ; various inquirers, as Schrb'n 

 (102) and Henle (50), have constantly found the discus pro- 

 ligerus near the deepest part of the follicle, where the latter is 

 most intimately connected with the ovarian stroma, and where 

 the supply of blood may be expected to be most free. Others, 

 again, as Coste (33), consider that the position occupied by the 

 discus is close beneath the most superficial part of the follicle. 

 I have met with it occupying both situations. 



In the above description of the structure of the ovum, those of 

 Invertebrata may be included, since the ova of all animals are 

 similar in their essential features, however much they may 

 externally appear to differ. 



The earliest rudiment of every ovum consists of a simple 

 cell, with soft granular protoplasm unenclosed by a membrane, 

 a nucleus, and a nucleolus. The peculiarities of the youngest 

 ova, that I, with His, term "primordial ova" will be more 

 minutely discussed in speaking of their development. Since 



