Knight — 32 — Dictionary 



Conditioned Dominance. — Dominance which is affected by 

 the presence of modifying genes (dominigenes). cf. Fancier's 

 Dominance. 



Conditioned Reflex. — A reflex action which results from 

 habit or experience on the part of the individual, cf. Uncon- 

 ditioned Reflex. 



Configuration. — An association of chromosomes at meiosis, 

 segregating independently of other associations at anaphase 

 (Darlington). 



Confusing Coloration. — A form of protective coloration 

 which confuses the predator by having a different appearance 

 according to whether its possessor is at rest or in motion. 



Congenital. — Present at, or dating from, birth, but not, 

 necessarily, inherited in the genetic sense. 



Congression. — The moving of the chromosomes into the 

 equatorial region at metaphase. 



Conjugant. — (i) A gamete at the time of fertilization, (ii) 

 One of two pairing chromosomes at synapsis. 



Conjugation. — (i) Side-by-side association of homologous 

 chromosomes at meiosis. (ii) Pairing of gametes or zygotes, 

 or fusion of two nuclei. 



Constriction. — An unspiralised segment of fixed position in 

 the metaphase chromosome (Agar; Darlington). 



Constriction, Centric. — The spindle attachment constriction. 



Constriction, Nucleolar. — A secondary constriction deter- 

 mined by the organisation of the nucleolus (Darlington). 



Constriction, Primary. — The centromere. 



Constriction, Secondary. — One separating a satellite from 

 the rest of the chromosome. 



Constriction, Tertiary. — Any constriction other than the 

 centromere (primary constriction) or one separating a satellite 

 (secondary constriction) from the rest of the chromosome. 



Contabescence. — Atrophy of anthers and pollen. 



"Contact" Hypothesis. — The theory that chromosomes oc- 

 casionally undergo illegitimate crossing-over between non- 

 homologous sections, resulting in an interchange of blocks 

 of genes (cf. Dobzhansky, 1941). 



Continuous Fibres. — 'Fibres' which connect the two poles 

 of a spindle, as distinct from chromosomal fibres and inter- 

 zonal fibres, q.v. 



Continuous Variations. — Those in which the variants differ 

 from each other by infinitely small steps as opposed to discrete 

 variations where the groups are distinct and there is no merg- 

 ing. Variations in height, weight, etc. are normally continuous. 



