28 Dr Martin Barry's Researches in Embryology. 



which his views have received from corresponding observa- 

 tions made by subsequent inquirers on the ova of other ani- 

 mals. He more particularly adverts to a recently published 

 memoir by Dr Keber, in which that physiologist describes 

 the penetration of the spermatozoon into the interior of the 

 ovum in Unto and Anodonta, through an aperture formed 

 by dehiscence of its coats, analogous to the micropyle in 

 plants. 



Small pellucid vesicles, lined with ciliated epithelium and 

 inclosing a revolving mulberry-like object, such as the author 

 discovered imbedded under the mucous membrane of the Rab- 

 bit's uterus, and described in the Philosophical Transactions 

 for 1839, have been likewise observed by Keber, not only 

 under the mucous membrane, but also and most frequently 

 in some part of the cavity of the abdomen. Keber considers 

 these bodies to be fecundated ova. The author agrees with 

 Keber in considering them to be ova, but he does not suppose 

 them to be fecundated, nor does he think that their mem- 

 brane is the vitellary membrane (" zona pellucida"), which 

 he believes to have been absorbed. He considers such ova 

 to have been detached from the ovary along with their con- 

 taining ovisac, which in their new situation constitutes the 

 ciliated capsule ; and as they present themselves in unimpreg- 

 nated animals, he now believes that the formation of a mul- 

 berry-like group of cells from the germinal spot, and the 

 process of division and subdivision of the latter, take place 

 without fecundation ; but when this happens, the mulberry is 

 not found to contain one cell larger than the rest, the nu- 

 cleus of which, according to his observations, is the embryo. 

 He is further of opinion, that in all cases of separation of 

 ova, the ovisac, or internal coat of the Graafian follicle, is 

 detached from the ovary, either entire and along with the 

 ovum, as in the instances alluded to, or after the ovum has 

 first escaped by rupture, as in the instance of the fecundated 

 ovum. 



The author is led to the following conclusions with refe- 

 rence to the structures connected with the ovum in different 

 animals : — 1. That in the Mammalia, the vesicle he described 

 as the foundation of the Graafian follicle, and termed the 

 ovisac, does not remain permanently in the ovarii, but is ex- 



