Knight — 156 — Dictionary 



Vegetative Nucleus. — (i) The larger of two nuclei in a 

 cell; macronucleus ; trophic nucleus; trophonucleus. (ii) Pollen 

 tube-nucleus. 



Vegetative Pole. — The lower portion of a telolecithal ovum 

 in which the yolk accumulates. 



Vegetative Reproduction. — Asexual reproduction by buds, 

 grafts, cuttings, layers, etc. 



Vegetative Segregation. — The production of two genetically 

 dissimilar cells at a somatic cell division, caused by some 

 sudden qualitative or quantitative change in the nuclear consti- 

 tuents, or by the segregation of two dissimilar cytoplasmic 

 constituents at the somatic cell divisions (Chittenden). 



Veratrine Sulphate. — Veratrine, a poisonous alkaloid, is 

 obtained from dried ripe seeds of Shoenocaulon officinale 

 and from rhizomes of Veratrum album and V. viride. The 

 sulphate is used in inducing polyploidy. 



Vernalization. — The treatment of seeds, before sowing, by 

 any technique designed to hasten the flowering period of the 

 plants to which the seeds give rise. 



Versatile Anthers. — Those having the filament attached 

 near the middle, so that the anther can readily turn in any 

 direction. 



Viable. — Capable of living more or less normally, capable of 

 germinating normally. 



Vicinism. — Out-crossing; natural cross-pollination. 



Vicinist. — A plant resulting from vicinism; a natural hybrid. 



Virgin Birth. — See Apogamy; Apomixis; Parthenogenesis. 



Vitamer. — One of two or more substances which have a 

 similar capacity for curing any specific deficiency syndrome. 



Vitamin. — A vitamin is a substance with a catalytic action 

 which is indispensable to animals. Since it cannot be syn- 

 thesized by animals and must be furnished by plants, its 

 origin is exogenous as far as animals are concerned. 

 (Schopfer). 



Vitamin A. — The fat-soluble vitamin controlling night-blind- 

 ness and the disease resisting power of mucous membranes. 

 Vitamin A is manufactured by the liver from carotene, q.v. 



Vitamin B^. — 0^2^18^420^13. The water-soluble, heat 

 labile, anti-neuritic vitamin controlling beri-beri; aneurin; 

 aneurine; thiamin; thiamine. 



Vitamin B2. — The water soluble, heat stable, anti-pellagra 

 vitamin complex which contains amongst other substances ribo- 

 flavine and nicotinic acid, q.v. 



