Ergosterol — 53 — Extlne 



Eumitosis. — Typical mitosis. 



Eumitotic. — Anaschistic, q.v. 



Euphemeral. — Of flowers: lasting not more than 24 hours. 



Euploid. — A polyploid whose chromosome number is an 

 exact multiple of the haploid number of the species from 

 which it arose. 



Euploid Polyembryony. — Multiple embryos which give rise 

 to haploids as well as polyploids. 



Eupyrene. — Normal (as applied to spermatozoa). 



Euryplastic. — Having considerable modificational plasticity, 

 q.v. N. Euryplasty. 



Eutelegenesis. — The use of artificial insemination for the im- 

 provement of the race. 



Euthenic. — Tending to produce better conditions for people 

 to live in, but not necessarily tending to produce people who 

 can hand on this improvement by heredity (J. Heredity). 



Exine. — See Extine. 



Exogamy. — Conjugation between gametes of different an- 

 cestry; outbreeding. 



Exogenous. — Arising from external tissues. 



Exogynous. — With the style longer than the corolla and 

 projecting beyond it. 



Exoplasm. — Non-granular, peripheral cytoplasm; ectoplasm. 



Explosive Speciation. — The rapid production, within the 

 one locality, of a number of new species from a single species. 



Expressivity. — The phenotypic degree of expression of a 

 gene; a measure of the amount of effect caused by a gene. 

 cf. Penetrance. 



Expressivity, Heterozygous. — The degree of dominance or 

 lack of dominance shown by a gene in the heterozygous state. 

 Full heterozygous expressivity is the equivalent of full domi- 

 nance, absence of heterozygous expressivity is the same as 

 complete recessiveness. 



Expressivity, Reduced. — The occurrence, within one geno- 

 type, of individuals showing a reduced manifestation of any 

 particular gene or genes. 



Exserted. — Of stamens: projecting beyond the corolla. 



Extension Factor. — A factor (gene) which extends the 

 action of a primary factor. Thus, in mammalian genetics, 

 black or brown pigments restricted chiefly to the eye, become 

 "extended" throughout the coat in black or brown varieties 

 (J. Heredity). 



Extine. — The outer membrane of a pollen grain. 



