Homologue. The same organ in different animals under every variety of form and function.

No naturalist has devoted more painstaking attention to the structure of the barnacles than Mr. Darwin.

The laws of Coexistence;-the adaptation of structure to function; and to a certain extent the elucidation of natural affinities may be legitimately founded upon the examination of fully developed species;-But to obtain an insight into the laws of development,-the signification or bedeutung, of the parts of an animal body demands a patient examination of the successive stages of their development, in every group of Animals.

That the variability of an organism to a certain extent is a constant and certain condition of life we admit, otherwise there would be no distinguishable individuals of a species.

Homologue. The same organ in different animals under every variety of form and function.

Analogue. A part or organ in one animal which has the same function as another part or organ in a different animal.

Cuvier had preceded Lamarck in specifying the kinds and degrees of variation, which his own observations and critical judgment of the reports of others led him to admit.