agar n. [Malay agar-agar, substance from seaweed] A nonni-trogenous, gelatinous hydrophilic substance obtained from certain seaweeds used in the preparation of culture media in microbiology and as a stabilizer of emulsions.
agastric a. [Gr. a, without; gaster, stomach] Lacking a digestive tract or cavity.
age n. [L. aevum, lifetime] 1. The period of time any living individual has existed. 2. A particular period of life or development.
age and area theory The older a species, the more extensive its area of distribution.
agenesis, agenesia n. [Gr. a, without; genesis, beginning] 1. Lacking development. see aplasia. 2. Inability to produce offspring. see agennesis.
agennesis n. [Gr. a, without; gennesis, an engendering] Impotent; sterile. agennetic a.
age polyethism (ARTHRO: Insecta) In social insects, the regular changing of labor specialization as they grow older. see polyethism.
aggenital a. [L. ad, to; genitalis, genitalia] (ARTHRO: Chelicer-ata) In Acari, pertaining to that area on both sides of the genital region.
agglomerate n. [L. ad, to; glomerare, to form into a ball] To group or gather into a mass or cluster; clustered densely; piled or heaped together.
agglutinate v. [L. ad, to; glutinare, to glue] To join by adhesion; to unite as with glue; to collect in masses.
agglutinated a. [L. ad, to; glutinare, to glue] 1. Sticking together. 2. (ARTHRO: Insecta) Used by entomologists to describe a larva with an unusually heavy chitinous covering. see obtect pupa.
agglutinin n. [L. ad, to; glutinare, to glue] A substance or specific antibody causing clumping of cells.
aggregate a. [L. ad, to; gregare, to collect] Clustering or crowding together to form a dense mass.
aggregation n. [L. ad, to; gregare, to collect] 1. Collection or grouping into a mass or sum. 2. A group of individuals comprised of more than a mated pair or family, collecting in the same place, that do not construct nests or rear offspring in a cooperative manner. see colony.
aggressin n. [L. aggressus, attacked] A substance produced in the body of a host by a pathogenic organism that paralyzes the defense mechanisms of the host.
aggression n. [L. aggressus, attacked] The behavior of an organism involving threats or attack of another organism or object.
aggressive mimicry A method of mimicry of one species by another that is hostile to it.
agigeriate a. [Gr. a, without; gigerium, gizzard] Gizzardless; without a gizzard.
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