DR. MARTIN BARRY’S RESEARCHES IN EMBRYOLOGY. 
591 
nous Fishes to resemble the corresponding parts in Birds. His description of these 
parts in osseous Fishes, is essentially the same as that of the corresponding parts in 
naked Amphibia. 
435. On examining the germinal vesicle in a Bird'j~, in one of the Batrachian 
Reptiles;};, and in several osseous Fishes^, I find it in many instances to contain — not 
m6rely spots but — nucleated cells ; the “shining globules” in naked Amphibia de- 
scribed by Wagner as having a high refracting power, being obviously the nuclei of 
these cells. We thus find that, as in the mammiferous ovum at a certain period, the 
germinal vesicle of these animals contains cells. 
436. But this is not all. When more closely examined, and especially after the 
addition of dilute spirit, many of the objects in question present an analogy still more 
striking, and one indeed which it is not presumption to consider perfect. Not merely 
does the germinal vesicle contain nucleated cells, but these cells are arranged in 
layers around a point which appears to be situated at the periphery of the vesicle ; 
the layers nearest to this point being opaker than the rest. The interior of many of 
the contained cells also presents an appearance, indicating a process of the same kind 
as that implied by the state of the germinal vesicle or parent cell. In short, the 
contents of the germinal vesicle in Birds, Batrachian Reptiles, and osseous Fishes 
are often found to be in a condition so nearly resembling that of the contents of the 
mature germinal vesicle in Mammalia, that a description of the one would be almost 
applicable to the other; the difference consisting merely in the period at which the 
nucleus of the germinal vesicle resolves itself into incipient cells. 
437* The analogy extends also to the substance surrounding the germinal vesicle, 
which is seen to consist of nucleated cells. 
438. It is extremely satisfactory to be thus enabled to refer to ova which are so 
easily obtained, for a confirmation of my observations on the mammiferous ovum. 
439. I have already alluded (par. 327 Note.) to a conjecture of Professor R. Wagner, 
that the presence of “ minute scattered globules ” in the riper ova of certain animals j] 
may be referable to a division of the primary “ spot;” which conjecture I think it will 
be seen was very near the truth. A previous suggestion, however, of the same author, 
it will be obvious, does not accord with my experience. He says with reference to 
ova of the naked Amphibia : “ It is perhaps not unimportant for future investigations, 
if the views of Schwann should be confirmed, that sometimes in minute and unripe 
ova *«one spot is remarkable from its being larger and opaker than the rest. It is 
perhaps the nucleus of the cell, while the others belong to the contents of the cell [zel- 
leninhalt]5[.” I do not think that the smaller “ spots” just mentioned belong to the 
“ zelleninhalt” or “contents of the cell,” in the sense, in which this term is used in 
f The Pigeon ( Columba domestica, Linn.). + The Frog ( Rana esculenta, Linn.). 
§ Among which were the Turbot and Plaice (Fleur, maximus and Platessa, Linn.). 
|| Squamous Amphibia and cartilaginous Fishes. “Ei,”p. 3. 
