| metamer | <chemistry> Any one of several metameric forms of the same substance, or of different substances having the same composition; as, xylene has three metamers, viz, orthoxylene, metaxylene, and paraxylene. See: Metamere. Source: Websters Dictionary (01 Mar 1998) |
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| metamere | <biology> Unit of segmentation or metamerism. (18 Nov 1997) |
| metameric | 1. <chemistry> Having the same elements united in the same proportion by weight, and with the same molecular weight, but possessing a different structure and different properties; as, methyl ether and ethyl alcohol are metameric compounds. See Isomeric. The existence of metameric compounds is due to the different arrangement of the same constituents in the molecule. 2. <biology> Of or pertaining to a metamere or its formation; as, metameric segmentation. Origin: Pref. Meta- + Gr. Part. Source: Websters Dictionary (01 Mar 1998) |
| metameric nervous system | That part of the nervous system which innervates body structures developed in ontogeny from the segmentally arranged somites or, in the head region, branchial arches. The term implies reference to the neural mechanisms intrinsic to the spinal cord and brainstem (represented by the sensory nuclei, motoneuronal cell groups, and their associated interneurons in the reticular formation); by strict definition it should exclude the autonomic nervous system. (05 Mar 2000) |
| metamerism | <biology> The condition of developing body segments (such as in earthworms). (09 Oct 1997) |