550 
DR. MARTIN BARRY’S RESEARCHES IN EMBRYOLOGY. 
these cell-like nuclei. But a decision of the question is obtainable only through de- 
monstration that the whole relation of such a cell-like nucleus is to a cell, the same 
as that of the ordinary nuclei of cells, namely, it must be shown that such a nucleus 
arises before the cell, that the cell forms itself as a layer around the nucleus, and that 
finally the nucleus is absorbed in the cell.” Again, referring to the experience of 
Schleiden, that in plants it is nearly if not quite universal that new cells arise within 
previously existing cells, Schwann remarks'^-, “ In animals — the formation of cells in 
cells is the rarer case, but happens in so far as that a three to four-fold generation 
may successively form in one cell. — In cartilage by far the most cells arise in the cy- 
toblastema external to the cells already present.” I shall think myself fortunate if 
any of the observations recorded in this or the preceding memoir, should contribute 
towards the solution of these and other questions. 
387- In my “Second Series,” after having applied the term “nucleus” to certain 
germinal vesicle-like objects observed in the cells of various parts j:, I suggested 
that perhaps the granules or globules surrounding those objects might, rather, have 
been the remains of a nucleus. I have now to state, that facts observed in the pre- 
sent “Series” confirm the view then taken. Thus the germinal vesicle-like objects 
in Plate XXVIII. fig. 245. a and |3 certainly correspond to those just referred to ; and 
they are situated in that which had been the nucleus of the cell. 
388. Now should it prove that I am right in considering the germinal vesicle-like 
objects of my “Second Series,” and those in Plate XXVIII. fig. 245. of this memoir, 
as corresponding to the pellucid cavity in a nucleus, it will be obvious that the relation 
of such an object to a cell, is not “the same as that of the ordinary nuclei of cells.” 
And since I cannot but regard those germinal vesicle-like objects as corresponding 
also to some of the “ hollow,” “pellucid,” and “cell-like nuclei” of Schwann, I ven- 
ture to believe that some light may have thus been thrown upon one of the difficul- 
ties left by that observer for future explanation. 
389. From these remarks, however, it will be seen that I cannot adopt the opinion 
of Schwann, that the pellucid object in epithelium-cells is a “ cytoblast.” And facts 
made known in the foregoing pages show that the germinal vesicle itself cannot be so 
considered. 
390. Schwann conjectures that the contents of the cell (“ zellen-inhalt”) may con- 
tribute to the secondary deposits observed to take place in plants on the inner surface 
of the membrane of the cell ; and which, according to Valentin, always occur in 
spiral or other lines. Schwann had not observed such secondary deposits in animal 
cells; yet from the correspondence he has pointed out between elementary structures 
in the two kingdoms, I think the following may perhaps be worthy of considera- 
tion. Schleiden remarks §, “The formation of secondary deposits on the inner sur- 
f L. c., p. 204. 
t L. c., Plate VI. fig. 110, Plate VII. figs. 120. 121, Plate VIII. figs. 129. 130. 132. 150. 
§ L. c., p. 146. 
