homologous

(h6-mol’6-gus), a. [=F. homologue = Sp. homélogo= Ve: homologo = It. omologo, ¢ NL. homolog us, Aéyoc, proportion, ete.] Having the same relative position, proportion, value, or struecture; having correspondence or likene . specifically —(a) In geom., corresponding in relative position and proportion; also, homological or in homology. (0) In aig., having the same relative proportion or value, as the two antecedents or the two consequents of a proportion. (c) In chem., being of the same chemical type or series; differing by a multiple or an arithmetical ratio in certain constituents, while the physical qualities are analogou with small differences, as if corresponding to a series of parallels: as, the species in the several groups of alcohols, fatty acids, and aromatic acids are homologous with the others in the same group. (d) In zodl. and bot., corresponding in type of structure; having like relations to a fundamental type. Thus, the human arm, the fore leg of a horse, the wing of a bird, and the swimming-paddle of a dolphin or whale, being all ea ee e entially of the same structural elements, are said to be homologous, though they are adapted for quite different functions, All physiologists admit that the swim-bladder is homologous, or ‘ideally similar” in position and structure, with the lungs of the higher vertebrate animals, Darwin, Origin of Species, p. 183. The ti ues themselves, in some cases of di imilar structure, may be homologous, but they are homologous ti ues, and not homologous parts of a system of ti ues, Be ey, Botany, p. 120.