Abdominal Cavity and Uterus. 325 



be called an ovum in B. But it contained a mulberry-like 

 body such as I had seen rotating on its axis. 



These observations leave no doubt at all that the vesicles 

 containing a mulberry-like rotating body have, as Dr Keber 

 supposed, their origin in the ovary ; — that they are not, how- 

 ever, ova, as he supposed them to be, but ovisacs. 



The said vesicles then being ovisacs, it is to be presumed 

 that the former ovum is represented by the rotating mul- 

 berry. How does the one become converted into the other \ 

 From what I saw in the Hog, it would seem that some of the 

 first changes, after the expulsion of the ovisac from the ovary, 

 are liquefaction of the yelk, absorption of the vitellary mem- 

 brane, and enlargement of the germ vesicle and spot.* What 

 follows I cannot say. But it is difficult to believe that there is 

 anything in the ovum or ovisac so likely to produce a ciliated 

 rotating mulberry-like body as the dividing and sub-dividing 

 germ spot ; for I shewed this spot to fill its vesicle by such di- 

 visions, and this before fecundation. An altered form of the 

 germ spot, therefore, I believe to be represented by the said ro- 

 tating body. The spot, as I have already said, is that of an un- 

 fecundated ovum. And in harmony with this is the important 

 fact, that the rotating body in the vesicles in question, though 

 perfectly resembling the mulberry in the fecundated ovum, 

 is much smaller, and contains in its interior no large cell with 

 a nucleus, which nucleus, according to my observations, is the 

 first appearance of what can be called the embryo.\ 



As to what becomes of these escaped ovisacs with their 

 remains of unfecundated ova, I am by no means of the opinion 

 that any of them are ever fecundated in the Fallopian tube 

 or uterus. My belief is that they are finally absorbed, for 

 in the same localities you find corresponding vesicles con- 

 nected by bloodvessels with the part where they are found, 

 having a thinner membrane, and either no more than traces 



* Phil. Trans., 1839, p. 320, PI. V., fig. 102/. 



t Von Baer's " primitive trace" exhibits a later stage, an altered form of 

 the nucleus of my large cell first seen in the centre of the mulberry, and then 

 passing to the surface. 



