| darter | 1. One who darts, or who throw darts; that which darts. 2. <zoology> The snakebird, a water bird of the genus Plotus; so called because it darts out its long, snakelike neck at its prey. See Snakebird. 3. <zoology> A small fresh water etheostomoid fish. The group includes numerous genera and species, all of them American. See Etheostomoid. Source: Websters Dictionary (01 Mar 1998) |
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| dartoic | <anatomy> Of or pertaining to the dartos. Source: Websters Dictionary (01 Mar 1998) |
| dartoic tissue | Tissue resembling tunica dartos. (05 Mar 2000) |
| dartoid | <anatomy> Like the dartos; dartoic; as, dartoid tissue. Origin: Dartos. Source: Websters Dictionary (01 Mar 1998) |
| dartos | <anatomy> A thin layer of peculiar contractile tissue directly beneath the skin of the scrotum. Origin: NL, fr. Gr. Flayed. Source: Websters Dictionary (01 Mar 1998) |
| dartos fascia | A layer of smooth muscular tissue in the integument of the scrotum. See: dartos muliebris. Synonym: tunica dartos, dartos muscle, membrana carnosa, tunica carnea. (05 Mar 2000) |
| dartos muscle | A layer of smooth muscular tissue in the integument of the scrotum. See: dartos muliebris. Synonym: tunica dartos, dartos muscle, membrana carnosa, tunica carnea. (05 Mar 2000) |
| dartrous | <medicine> Relating to, or partaking of the nature of, the disease called tetter; herpetic. Dartroud diathesis, A morbid condition of the system predisposing to the development of certain skin deseases, such as eczema, psoriasis, and pityriasis. Also called rheumic diathesis, and hipretism. Origin: F. Dartreux. See Dartars. Source: Websters Dictionary (01 Mar 1998) |
| Darwin | Charles R., English biologist and evolutionist, 1809-1882. See: darwinian ear, Darwinian evolution, darwinian reflex, darwinian theory, darwinian tubercle. (05 Mar 2000) |
| Darwin, Charles | <person> An English naturalist who lived from 1809 to 1882, he studied and documented the flora and fauna of parts of coastal South America, including the Galapagos Islands, but is most famous for developing the theories of evolution and natural selection. Lived: 1809-1882. (09 Oct 1997) |
| darwinian | Pertaining to Darwin; as, the Darwinian theory, a theory of the manner and cause of the supposed development of living things from certain original forms or elements. This theory was put forth by Darwin in 1859 in a work entitled "The Origin of species by Means of Natural Selection." The author argues that, in the struggle for existence, those plants and creatures best fitted to the requirements of the situation in which they are placed are the ones that will live; in other words, that Nature selects those which are survive. This is the theory of natural selection or the survival of the fillest. He also argues that natural selection is capable of modifying and producing organisms fit for their circumstances. See Development theory, under Development. Origin: From the name of Charles Darwin, an English scientist. Source: Websters Dictionary (01 Mar 1998) |
| darwinian ear | An auricle in which the upper border is not rolled over to form the helix, but projects upward as a flat, sharp edge. (05 Mar 2000) |
| Darwinian evolution | The proposition that the phylogeny of all species is wholly ascribable to the combined effects of random variation (mutation) in genotypes of the members of a stock as a result of the operation of undirected accidents with consequences to their phenotypes and the operation of preferential (but by no means certain) survival of those resulting phenotypes most suited to survive in the contemporary environment. The proposed system survives largely because of genetic factors that avidly conserve the ontogeny of the stock. (05 Mar 2000) |
| darwinian reflex | The tendency of young infants to grasp a bar and hang suspended. Compare: grasping reflex. (05 Mar 2000) |
| darwinian theory | The theory of the origin of species and of the development of higher organisms from lower forms through natural selection (survival of the fittest in the struggle for existence), and of the evolution of humans from an ancestor common to himself and the apes. (05 Mar 2000) |