Knight — 68 — Dictionary 



capable of being transmitted from generation to generation 

 although the outward signs of the presence of this mechanism 

 may only be apparent under specific conditions. 



Hereditary Univalents. — Chromosomes which have evolved 

 a system of more or less even distribution in segregation with- 

 out going through the process of pachytene pairing, cf. Spon- 

 taneous Univalent. 



Heredity. — The transmission of parental qualities, expressed 

 or latent, to the progeny. 



Heritability. — The portion of the observed variance for 

 which differences in heredity are responsible. 



Herkogamy. — See Hercogamy. 



Hermaphrodite. — In plants, monoclinous or monoecious; 

 having the organs of both sexes in one individual. 



Hermaphroditism. — The condition in which the reproductive 

 organs of both sexes are present in one individual. 



Heterauxesis. — The relation of the growth-rate of a part 

 of a developing organism (whether morphological or chemical) 

 to the growth-rate of the whole or of another part ; a compari- 

 son between organisms of the same group but of different 

 ages and hence sizes (Huxley, Needham and Lerner). 



Heteroauxin. — B-indolylacetic acid, a plant growth stimulant 

 present in urine. 



Heteroauxone. — Any substance which is biologically highly 

 active but which the organism does not, itself, synthesize. 



Heterobrachial Chromosome. — A chromosome which is 

 divided into two unequal segments by the centromere. 



Heterocarpous. — Producing more than one kind of fruit. 



Heterocaryon, Heterokaryon. — An individual whose cells 

 are heterokaryotic. 



Heterocaryosis. — Heterokaryosis, q.v. 



Heterocephalous. — With staminate and pistillate flowers 

 on separate heads on the same plant. 



Heterochlamydeous. — Having the perianth clearly divided 

 into a calyx and a corolla. 



Heterochromatic. — Of a chromosome, or portion of a chromo- 

 some: staining deeply (and presumed to consist of genetically 

 inert material), cf. Euchromatic. 



Heterochromatin. — Deeply staining chromatin presumed to 

 be genetically inert, as opposed to euchromatin which is geneti- 

 cally active and stains less deeply. Heterochromatin remains 

 condensed and stainable during interphase. The heterochro- 

 matin possibly contains the polygenes. 



