Aetiology see etiology

afference n. [L. ad, near; ferre, to bear] Impulses from the external sense organs of an animal because of events in the environment. see reafference.

afferent a. [L. afferre, to bring] Refers to a structure or vessel that leads to or toward a given position. see efferent.

afferent channel (ARTHRO: Crustacea) The opening through which water passes to the gills.

afferent fiber A nerve fiber carrying impulses from a receptor to the central nervous system.

afferent nerve A nerve that conducts impulses from the periphery toward a nerve center; the axon of a sensory neuron between a receptor and the central nervous system.

afferent neuron (neurone) A sensory neuron that conveys inward impulses received or perceived by a sense organ from external sources.

affinity n.; pl. -ties [L. affinis, related to] Relationship; sometimes misleadingly employed as synonym for phenetic similarity.

aflagellar a. [Gr. a, without; L. flagellum, whip] Without flagella.

afterbody a. [A.S. aefter, behind; bodig, body] (ARTHRO: In-secta) In Coleoptera, the body area behind the pronotum.

after-discharge 1. The continuing discharge of impulses after stimulation has ceased in sensory receptors. 2. The continuation of the motor response (reflexes) after discontinuance of stimulation. see after-sensation.

afternose a. [A.S. aefter, behind; nosu, nose] (ARTHRO: In-secta) Pertaining to the triangular area below the antennae and above the clypeus.

after-sensation Continuation of nerve impulses after cessation of external stimulation of sensory apparatus.

agameon n. [Gr. a, without; gamos, marriage; on, being] A species reproducing exclusively by apomixis. see apomic-tic (ameiotic) parthenogenesis.

agamete n. [Gr. a, without; gamos, marriage] Any product of reproductive multiple fission that develops directly into the adult form without sexual union.

agamic a. [Gr. a, without; gamos, marriage] Parthenogenetic; reproduction without mating, may be either mitotic or mei-otic.

agamobium n. [Gr. a, without; gamos, marriage; bios, life] The asexual form in alternation of generations. see gamo-bium.

agamodeme n. [Gr. a, without; gamos, marriage; demos, people] A population mainly consisting of asexual organisms.

agamogenesis n. [Gr. a, without; gamos, marriage; genesis, beginning] Asexual reproduction; parthenogenesis; reproduction without fertilization by a male gamete. agamoge-netic a. see gamogenesis.

agamospecies n. [Gr. a, without; gamos, marriage; L. spe cies, kind] A species without sexual reproduction; an asexual species.

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