48 Dr. M. Barry's Remarks on a Work by Prof. Bischoff. 



have shown the mode of origin of the spot, " Fruchthof," or 

 tache embryonnaire, — and the supposed "original foundation of 

 the body of the embryo" ( Bischoff'' s fig. 48) to be merely a 

 st age in the growth of what had come into existence some time 

 before: Bischoff would have seen the "primitive trace" of 

 authors to be an accumulation of the cells, or foundations of 

 cells, continually arising in what had been a pellucid space, 

 and marking the locality of the nucleus of the embryonic cell, 

 — the central pellucid groove or channel (" Primitivrinne") in 

 Bischoff 's " original foundation of the body of the embryo " 

 being no other than the elongated pellucid centre of that 

 nucleus. 



Bischoff adopts the views of others, that the germinal mem- 

 brane "thickens" at a certain part, and that in this thickened 

 portion the embryo has its origin. What is the cause of this 

 supposed thickening of a membrane? It is no other than that 

 continual origin of new cells in the pellucid centre of what had 

 been the nucleus of the embryonic cell, and the continual re- 

 production of the cells so arising. As the embryonic cell 

 exists in the mulberry while the mulberry is in the centre of 

 the ovum, its nucleus is no part of any membrane. Had in- 

 vestigators begun with smaller ova, — i. e. at an earlier period, 

 — and had they left no " small [?] hiatus " in their observa- 

 tions, they would have found that it is not a previously exist- 

 ing membrane which gives origin to the embryo, but a previ- 

 ously existing mulberry-like body, which, by certain changes, 

 assumes the form of a membrane, in a certain part of which 

 the development of the already existing embryo proceeds, in 

 the way I have described — from the nucleus of a cell. 



It might appear remarkable that Bischoff should not attach 

 much importance to the "small [?] hiatus" just referred to, 

 since in the same page (p. 91) he had only just said that the 

 changes follow one another with such rapidity that "an accu- 

 rate understanding is scarcely possible, if all the intermediate 

 stages have not been observed." But, notwithstanding this 

 most just remark, a "small [?] hiatus" seems to be no un- 

 common thing in the observations of Professor Bischoff. Thus 

 it appears (p. 54) that his "conclusions" respecting figs. 185, 

 188, 189, 190, 193, 194, 195, 199, 200, &c. in the "Third 

 Series" of my "Researches in Embryology" (Phil. Trans. 

 1840), were drawn from an examination of the ova of only 

 three rabbits (pp. 53, 54); the ova of one of these having lain 

 in water, and those of another not having been taken out of 

 the oviduct until "nine hours" (p. 57) "after the rabbit had 

 been killed." Again, on the subject of what is stated in my 

 "Third Series" concerning changes following fecundation 

 before the ovum leaves the ovary, he ventures to pronounce 



