Researches in embryology. (Second series) / by Martin Barry.

Date:
1839
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Licence: Public Domain Mark

Credit: Researches in embryology. (Second series) / by Martin Barry. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    free from the dark granules or gloljules of the preceding- stage. One of the central vesicles in this figure presented an indistinct spot. The object in fig. 81. is from the ovary of the common fowl. Its central part resembled the objects in figs. 83 and 84, from the Rabbit (par. 292. Note.). Facts noticed by preceding Observers, cited to show the Accordance in various respects between the Development of Mammalia and that of other Animals. 243. I have copied from CARUs-f the drawing of a structure (Plate VIII. fig. 131.) occurring in the ovum of one of the MoUusca,— Unio tumida. With this I would com- pare fig. 130. The latter represents a structure of the same kind as that whicii in Mammalia closely invests the embryo, and seems to enter into the formation of the amnion; the foriuer exhibits an object which, in the molluscous animal above-men- tioned, appeared to Carus to be the foundation of the shell. The Professor saw a similar structure in ova of Anodonta. The rhombick fields in the figure from Carus, as that author terras them, (which appear to me to have been vesicles with nuclei) seemed to become more numerous as development pi'oceeded. With this ob- servation I would compare what has been stated (par. 174 to 178. 180. 314 to 318.) regarding the greater number and smaller size of the successive sets of vesicles in the mulberry-like structure met with in several stages of the mammiferous ovum, (Plate VI. figs. 1051 to 110., Plate VIII. fig. 130.). 244. In the ovum of some of the Crustacea, there occurs a striking resemblance in appearance to the structure, just referred to in the Mammalia, when it has attained a more advanced stage. Such for instance is the case in the ovum of the Crafish, Astacus fli(viatil(s\. Spiders present in their ova a resemblance equally remarkable. With Plate VI. fig. 114. am. I would compare, for example, the ova of Epeira diadema. as figured by Herold§. Now in those animals, the structure which I suppose to cor- respond to that marked am. in tny figures, appears to enter into the formation of the outer covering of the abdomen. 245. In none of the figures of the authors last referred to, iiave I been able to dis- cover any trace of what seems to me entitled to be denotninated a germinal mem- brane. But, on the other liand, there is to be recognised in a great number of tliose figures, an unquestionable similarity at the part where the embryo arises, to the cor- responding part in the ovum of Mammalia. 246. Rathke describes a depression in the ovum of the Crafishl], and also in that of Bopijrus squillarum^, which in some respects appears closely to resemble tliat wliich I suppose to be the corresponding part in Mammalia, as shown in Plate VI. fig. 114. a.p. t Neue Untersuchungen iiber die Entwickelunjjsgescliiclite unserer Fhissmuschel, Tab. il. fig. 1. + Rathke, Flusskrebs, Tab. I. § Untersucbiingen iiber die Bildungsgescliichte der Wirbellosen Thiere im Eie, Theil I. II Flusskrebs, Tab. I. fig. 2. ^ Zur Morphologie Reisebemerkungen aus Taurien, p. 44.
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