352 EICHARD ASSHETON. 



intervals, some singly, others in groups of two, three, or, in 

 one case, as many as seven cells, upon the lower or ab- 

 embryonic pole. 



Figs. 40 and 41 are drawings of some of these seen in 

 section. The trophoblast layer is thick {T. R.), the hypoblast 

 layer [H.) is very uncertain, and is probably a network, and 

 on the outer surface of the trophoblast a few isolated cells 

 (7^. R.") form conspicuous objects. These cells are in every 

 way exactly comparable in their colour, texture, and size of 

 nucleus with the cells of the trophoblast layer. They are 

 never present before this time ; they disappear very quickly 

 afterwards. 



I am quite sure they are not derived from the walls of the 

 uterus. They are not leucocytes, nor are they corpuscles of 

 the secretion of the uterine glands. Such are, indeed, present 

 at this and an earlier period, but cannot be mistaken for 

 embryonic cells. The epithelium of the uterus is still per- 

 fectly sound, and shows no sign of degeneration until after 

 the fourteenth day. It becomes detached about the seventeenth 

 day. 



I have very little doubt of the origin of these scattered cells. 

 I think they are the detached fragments of the trophoblast 

 from the embryonal area. 



The uterus at this time contains ciliated cells, whose action, 

 no doubt, helps the passage of the blastodermic vesicles down 

 the uterus. It seems very likely that the broken fragments 

 are swept along by the action of the cilia, and adhere for some 

 time to the walls of the blastodermic vesicle until ultimately 

 swept or rubbed off altogether. 



Fig. 42 represents a section taken through a larger piece, 

 which was only a short distance from the embryonal area 

 of another specimen. The clear line which invariably 

 marks them off from the walls of the blastocyst makes it 

 unreasonable to suppose that they have been budded off 

 in situ. 



I think there can be no doubt that the cells which I find and 

 have just described are the same as those described by Weysse. 



