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.

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    he part so called, obviously corresponding to the aorta in other aniraals; and, according to the above diagram, having a truly thoracic and abdominal locality.* Of the development of molluscous animals, we know very lit- tle : enough, however, to render it quite safe for us to extend to them the laws already laid down ; viz. of the heterogeneous ari sing only out of the homogeneous, and of identity in the manner of histological and moi-phological separation (the manner of de- velopment),-]- whatever may be the direction which the latter takes, and however limited its degree. Even to Zoophytes, the same laws may be applied. The Germinal Granule of the Polype—a homogeneous, shapeless mass —separates into a softer portion, on the one hand ; and a more rigid, a horny, or calcareous substance, on the other ; and as- sumes its proper, more or less special, form. Even shoots themselves—those, for example, of the Hydra | —are at firs simple swellings, then cone-like, afterwards somewhat cylindri- cal, and gradually become funnel-shaped, like the parent : pro- cesses then appearing wart-like, at the circumference of the common cavity, and these by degrees elongating into arms.§ The whole animal kingdom then, (perhaps all organized beings.?), rnay be considered as directed in development by the above laws; and all animals present besides, the antithesis of an ' The Germinal Membrane separates, as well in invertebrated, as in verte- brated animals, primarily into a Serous or Animal, and a Mucous or Vegeta- tive lamina; between which, sooner or later, there is found a third, the Vascular lamina (Valentin, 1, c, p. 605). The above figure (10.) is not intended to present the fwrn of anj of the Arthrozoa. The form, indeed, of an Osteozoon, has been as far as possible adopted, in order to admit of an easy comparison of corresponding parts; the only purpose here, being to shew the appropriation of the Animal layer of the germinal membrane in the two Classes. We do not at present enter into any comparison in form, of parts of the external skeleton of the Arthrozoa, with the osseous system of Vertebrated animals (Osteozoa). t See Von B'dr^s researches on Snails, already mentioned: also those of Stiebel and Carus, alluded to by Burdach, Physiologie als Krfahruiigswissen- schaft, Band ii. S. 179-180. + Carm. plate i, fig. 1. § Burdach, 1. c. p. 1G4-1.