On the unity of structure in the animal kingdom / by Martin Barry.

Date:
[1837?]
Catalogue details

Licence: Public Domain Mark

Credit: On the unity of structure in the animal kingdom / 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.

    12/34 (page 6)
    Fig. 2. a, b, c, d, e, f, as above. p Fluid contained in the Graafian Vesicle. A Graafian Vesicle. The following table* shews how generally, the more difficult to discover of these parts, have already been met with in the animal kingdom. Germinal Vertelrata. Mammalia,including Man, Aves, Eeptilia, Pisces, Mollusca, Arliculata. Annelida, . Crustacea, Arachnida, Insecta, Zoophyla, Entozoa, Infusoria, Vesicle. Spot. Layer. It is then fair to presume,—since this table contains both ends, as they have been termed, of the animal world,—viz. In- fusoria and Man,—that wherever there exists what is called a perfect ovum, all the above parts are present. There are reasons for supposing- that the Germinal Vesicle is formed before the Yolk,—one of which is afforded by its rela- tively greater size; + and, if so, the Germinal Vesicle, with its contents, constitute the primitive portion of the ovum, which in all animals, where found, appears to be essentially the same. % It has thus been shewn, that in all classes of animals, from Infusoria to Man, germs at their origin are essentially the same in character; and that they have in common a homogeneous or general structure. ' Compiled from various sources. t The Germinal Vesicle is met with in those ova only, that are not quite ready for impregnation ; as it bursts on the latter taking place, and pours its contents among the granules of the Germinal layer, by which it is surrounded.