Knight — 40 — Dictionary 



ing value of two males by breeding them at different times to 

 the same females and comparing the average performance of 

 the progenies. 



Dialycarpic. — Having two or more carpels, all separate i.e. 

 apocarpic. 



Dialypetalous. — Polypetalous ; having several distinct (sepa- 

 rate) petals. 



Diandric. — Of a genetic character: passing from female to 

 female through the male by means of the sex chromosome 

 (birds and moths). 



Diarch. — A type of anastral spindle in higher plants that is 

 bipolar from the beginning ( Strasburger ; Wilson). 



Diaschistic. — Of bivalents that are said to divide transversely 

 at the first division; this is owing to the chromosomes being 

 united by a single terminal or nearly terminal chiasma (Far- 

 mer & Moore; Darlington). 



Diastem. — The plane of mitotic division of a cell. 



Diaster. — The stage at the end of mitosis or meiosis when 

 the daughter chromosomes are grouped near the poles of the 

 spindle. 



Dibasic. — Allopolyploid, q.v. 



Dicaryotic. — Dikaryotic, q.v. 



Dicentric. — Having two centromeres. 



Dichlamidius Chimaera. — A periclinal chimaera in which 

 the genetically distinct peripheral tissue is two layers of cells 

 thick. 



Dichlamydeous Chimaera. — Dichlamidius, q.v. 



2, 4-Dichlorophenoxyacetic Acid. — A growth regulating 

 substance which has been used with considerable effect at low 

 concentrations in flower induction. At higher concentrations 

 this substance is used as a selective herbicide (cf. Overbeek, 

 1945). 



Dichogamy. — The absence of simultaneous maturation of 

 stamens and stigmas in a flower so that their ripening does not 

 overlap and cross-pollination is ensured. Adj. Dichogamous. 



Diclinous. — Having staminate and pistillate flowers either on 

 the same plant or on different plants. 



Dictyate Stage. — Dictyotic stage, q.v. 



Dictyokinesis. — The division of the Golgi apparatus at 

 mitosis and the even distribution of dictyosomes between the 

 daughter cells. 



Dictyosome. — One of the elements which make up the Golgi 

 apparatus. 



