Dr Martin Barry's Researches in Embryology, 45 



of animals. Then the first change after their expulsion from 

 the ovary seems to be the disappearance by liquefaction of 

 the " zona pellucida ; M * which is not surprising, for it arises 

 as a mere fluid,f and seems never to reach more than a gela- 

 tinous consistence in the ovary. In the Rabbit, when the ovi- 

 sacs thus expelled with their unimpregnated ova do not pass 

 into the cavity of the abdomen, but enter the uterus, they 

 become connected therewith by bloodvessels, and seem to 

 exist for a while therein as parasites. The mulberry-like re- 

 volving body they contain, no doubt consists of the group of 

 cells arisen from nuclei into which the germinal spot divides 

 and subdivides ; which divisions and subdivisions, therefore, 

 I believe to take place without fecundation. But when this 

 happens, they do not lead to the formation of a cell larger 

 than the rest, which I have compared to a queen-bee in the 

 hive. The epithelium with vibrating cilia seen by Keber on 

 the inner surface of the membrane of these vesicles, appears 

 to me to have been what Von Baer denominated the mem- 

 brana granulosa; each granule having become an epithe- 

 lial cell. The membrane of the vesicles in question, there- 

 fore, lined by such an epithelium, / believe to be that of my 

 ovisac. 



From these remarks it will be seen that, though not taking 

 the same view as Keber on one point, I believe that physi- 

 ologist to have shewn that the mulberry-like body described 

 by myself in the Philosophical Transactions for 1839, as re- 

 volving on its axis, was the essential part of an unfecundated 

 mammiferous ovum. That observation of mine was quite 

 incidental, but I have the satisfaction to know from Bischoff's 

 own remarks that it was that observation that led him to 

 look for a revolving body in the ovum of the Mammalia,J 

 and which he was so fortunate in one instance as to find. It 

 was the fibrous membrane, — the layer of granules on its inner 

 surface, — the connection by bloodvessels with the uterus, — 



* See a drawing I gave of such an ovisac from the infundibulum in the Hog. 

 Phil. Trans. 1839. Part ii., Plate 5, fSg. 102, h and /. 

 t Phil. Trans., 1838. Part li., Plate 8, fig. 70,/. 

 % See a paper of his in Muller's Archiv for the following year, 1840. 



