Lecture introductory to the course of general anatomy : delivered in the University of London, on Wednesday, October 6, 1830 / by James R. Bennett.

  • James Risdon Bennett
Date:
1830
Catalogue details

Licence: Public Domain Mark

Credit: Lecture introductory to the course of general anatomy : delivered in the University of London, on Wednesday, October 6, 1830 / by James R. Bennett. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    that variety in form and structure is determined.* Accord- ing to them ; animated bodies receive certain degrees of organization, which enable us to divide them into their respective genera and species. But in their formation, they all commence in a similar low origin, and as before observed, it is solely upon extent of development that the form and the functions, not only of the animal but of its several parts, depend. Let us suppose for instance,—and there may be some grounds for the supposition,—that the ova from which four different animals are to be produced, are perfecily idea'cicai; and that these being placed under the necessary favourable circumstances, set out at the same moment in the march of formation. Now, if after a certain progress, one of these ova be arrested in the course of its composition, the result is, that we shall have an animal of a low degree of organization, as, for instance, a fish ; from the second ovum, where the de- velopment has proceeded further, we shall have a reptile ; from a third, where it has been continued still, a bird; and from a fourth, a higher degree of perfection is attained in a mammiferous animal. But it is to be particularly observed, that at no period of its development, does an animal of a high class resemble in its totality an animal of a lower class, and this arises from the circumstance that all the organs are not synchronous in their development; one is more rapidly formed than another; while one organ resembles its corresponding organ in a low animal, another vol! be analogous to that of a much higher animal. Thus, at the very moment that the nervous system may be on an equality with the nervous system of a reptile, the heart may have surpassed the heart of a reptile, and be analogous wdth that of a quadruped. Again, the external form or * Reference was here made to a plate displaying a classification of the laws of variety, as determined by Meckel, in his work upon Com- parative Anatomy.
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