n, 2n. — The gametic and somatic (zygotic) chromosome num- 

 bers respectively. 



Naphthaleneacetic Acid. — A growth regulating substance 

 which has been used with considerable effect, at low concen- 

 trations, in the induction of flowering (c/. Overbeek, 1945). 



Napierian Logarithms. — For conversion figures see Appen- 

 dix 1. 



Natural Logarithms. — Napierian logarithms, q.v. 



Natural Selection. — The automatic selection which takes 

 place under natural conditions by reason of the death or partial 

 inhibition of individuals less fitted to thrive under the condi- 

 tions obtaining. 



Neanic. — Pertaining to primitive or larval growth. 



"Necktie" Association (of chromosomes). — Two attached 

 bivalents connected by a 'hump' on each of them. Such a hump 

 is thought to be an indication that chiasmata cannot be ter- 

 minalized, either by reason of lack of homology at the ends 

 of the chromosomes or through the inhibiting effect of secon- 

 dary constrictions. 



Necrohormones. — Products of degenerating nuclei which are 

 thought to stimulate mitosis. 



Neighbourhood. — A population in which the individuals are 

 neighbours in the sense that their gametes may come together 

 (Sewall Wright). 



Neocarpy. — The flowering and fruiting of plants while still 

 immature. 



Neo-Darwinism. — A theory of evolution which, whilst taking 

 account of modern genetic facts, postulates that natural selec- 

 tion is the chief agency in bringing about evolutionary pro- 

 cesses. 



Neoergosterol. — A steroid, of the Vitamin D group, which 

 shows oestrogenic properties. 



Neoteinia. — Neoteny, q.v. 



