Androecium — 9 — Antherldial Mother-cell 



Aneuploid. — An organism whose somatic nuclei do not con- 

 tain an exact multiple of the haploid number of chromosomes, 

 one or more chromosomes being represented more times than 

 the rest ; an irregular, or unbalanced, polyploid, cf. Orthoploid. 



Aneurin, Aneurine. — Vitamin B^ (Cj2HjgN^SOCl2) the 

 anti-neuritic vitamin; thiamine, thiamin. 



Angstrom. — .0000001 mm. 



Anhydro-hydroxy-progesterone. — Pregneninolone ; a pro- 

 gesterone-like substance which retains its activity when ad- 

 ministered orally. 



Anisogamete. — A gamete which differs morphologically or 

 in size from its partner ; heterogamete. 



Anisogamy. — (i) Conjugation of anisogametes ; heterogamy, 

 (ii) The state of having anisogametes. 



Anisogenomatic. — Of a chromosome complement : composed 

 of two, or more, non-homologous sets. 



Anisogenous. — Of plants whose male and female gametes 

 behave dissimilarly in the transmission of inherited characters. 

 N. Anisogeny. cf. Isogenous. 



Anisogeny. — See Anisogenous. 



Anisoploid. — (i) Having an odd number of sets of chromo- 

 somes in the somatic cells, (ii) An individual of this type. 



Anisopolyploidy. — The state of having an odd number of 

 sets of chromosomes in the somatic cells. 



Anisotropy. -— Of ova: having a predetermined axis. 



Anlage. — Foundation or 'scaffolding' of embryo. Primitive 

 elements out of which a cell, organ or organism is formed 

 (Beadnell). 



Anoestrum, Anoestrus. — The resting period, or period of 

 absence of sexual desire which recurs between heat periods 

 in mammals ; the period when the female is not 'on heat'. 



Anorthospiral. — Having a spiralization of such a type that 

 a secondary compensational twisting occurs in the substance 

 of the thread, in addition to the straight-forward twist of the 

 spiral, cf. Orthospiral. 



Anovular Menstruation. — Periodic uterine bleeding similar 

 to that of menstruation but occurring in the absence of ovula- 

 tion and, consequently, of any corpus luteum. 



Anther. — The upper, fertile, part of a stamen, containing the 

 pollen. 



Antheridial Mother-cell. — A cell within the pollen grain 

 of flowering plants which divides to form the male gametes 

 (Bower). 



