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DR. MARTIN BARRY’S RESEARCHES IN EMBRYOLOGY. 
the doctrine of “ cells,” namely, to denote a substance which is supposed to have arisen 
independently of the nucleus. From my observations, the smallei' “ spots” in the naked 
Amphibia and osseous Fishes also, are produced by a resolution of the nucleus; and 
the “larger and opaker” “spot” seen by Wagner may have been, net as he conjec- 
tures the entire nucleus of the cell, but the central, unresolved, and most important 
portion of that nucleus. — As to the “ zelleninhalt” or “ contents of the cell,” I may 
here remark that I do not recollect to have met with such a substance in a solid state, 
in which there was not every reason to believe that it had arisen from the resolution 
of more or less of a nucleus, or from that of the nuclei into which a nucleus becomes 
resolved -f. 
440. The following is the experience of R. Wagner on the germinal spot in the 
ovum of some of the Invertebrata. If, in the perusal of it, my observations on the cor- 
responding part in the mammiferous ovum be borne in mind, I think it will be found 
that here also the analogy is not wanting. 
441. In Insects, “ the germinal spot — or opaker portion of the contents of the ger- 
minal vesicle — in some instances appears as a single, dark, granular, spherical mass, 
which admits of being separated with the compressorium into different forms, ** # or 
it is an accumulation of minute isolated globules ; — in some instances also, it is a 
delicate, finely granular, almost membranous-like layer, near which there sometimes 
appear one or more dark spots ; or finally (in rare cases) there are present scattered 
germinal spots, as in osseous Fishes and naked Amphibia^.” In the Arachnida, “ the 
germinal spot** # sometimes appears as though it were an accumulation of grains, in- 
closed by a membrane ; sometimes there are several accumulations of granules, and 
among them one or two larger spots§ .” In the Crustacea, “ the germ-nucleus or spot 
is always present, and of manifold forms.” It is sometimes “a large heap of grains” 
— in some instances “circumscribed by a membrane, rarely with some accessory 
spots” — in others, “an accumulation of twelve and more grains §.” In Astacus and 
Gammarus, the same naturalist always found “ minute spots on the inner surface 
of the germinal vesicle, as in Batrachians and osseous Fishes §;” which spots he de- 
f The discoid objects constantly referred to in some parts of the foregoing paper, we have seen to pass into 
cells of the same form ; and it is not easy to say where the disc terminates and the cell begins : so that in 
many instances I have been obliged to use almost indiscriminately the terms “disc” and “cell.” I do not 
recollect indeed to have observed any of these discoid objects in the transition state in question, in which there 
was not an appearance in the most superficial part of the interior, denoting decomposition of the outer portion 
of the disc. So uniformly has this been met with, that I am ready to suppose the formation of the cell-mem- 
brane to be connected with such decomposition, or perhaps dependent on it. Valentin, though agreeing with 
other authors as to the order of formation of the parts connected with the cell, mentions not having observed 
the formation of the cell-wall to have taken place until the nucleus was everywhere surrounded with the future 
“zelleninhalt” or contents of the cell (Repertorium, 1839. II., p. 285.). Did not the “ zelleninhalt,” seen by 
Valentin, consist of the outer portion of the previous “ cytoblast ?” 
% “ Ei,” p. 4. § Ibid. p. 4. 
