Knight — 2 — Dictionary 



Achlamydeous. — Possessing neither calyx nor corolla. 



Achromasie. — The expulsion of chromatin from a nucleus. 



Achromatic Figure. — The frame-work of 'fibres', or striations, 

 which is formed between the two poles and the equatorial 

 region, or between the two centrioles and the equatorial region, 

 during cell division. 



Achromatin. — The non-staining basic substance of the nucleus 

 excluding the chromatin. 



Achromatoplasm. — The non-staining protoplasmic reticulate 

 cell-matrix. 



Achrosome. — The structure forming the apex of a mature 

 spermatozoon, cf. Acroblast. 



Acidophil. — Having the property of staining heavily in the 

 presence of acid dyes. 



Acquired Character. — A structural or functional modifica- 

 tion which is impressed on the organism in the course of 

 individual life, but which is not the result of the action of 

 hereditary factors. 



Acroblast. — A body, or group of bodies, in the spermatid, 

 derived from the substance of the idiozome and Golgi-bodies, 

 from which arises the acrosome. Variously called Tdiosome', 

 'sphere', 'archoplasm', etc. (King; Wilson). 



Acrosome. — Achrosome, q.v. 



Activity-range. — The area within which individuals of a 

 single generation may move. 



Adaptation. — (i) Any structural or physiological change on 

 the part of the individual, species, etc., which makes it more 

 fitted to survive under given environmental conditions, (ii) 

 The process of changing in this way. 



Adaptive Radiation. — (i) The evolution of several closely 

 related but morphologically and ecologically divergent forms 

 (Cain, 1944). (ii) The presence, within a systematic group, 

 of various types modified to suit mutually exclusive ways of 

 living. 



Additive Factors. — Cumulative factors; non-allelomorphic 

 factors affecting the same character and enhancing each other's 

 effect. Such factors are said to show Additive Effect. 



Adermin. — Vitamin Bg. 



Adrenosterone. — An androgenic substance first extracted by 

 Reichstein from the suprarenal cortex. 



Afterbirth. — The placenta and foetal membranes when ex- 

 pelled from the uterus following parturition; decidua. 



