Knight — 76 — Dictionary 



Hyperchromasy. — Of a cell: possessing an abnormally high 

 proportion of chromatin before division. 



Hyperchromatosis. — Hyperchromasy, q.v. 



Hypercyesis. — Fertilization of a second ovum in a pregnant 

 animal after a considerable interval from the original concep- 

 tion. 



Hyperdiploidy. — The state of having a translocated portion 

 of a chromosome present in addition to the normal comple- 

 ment; sectional hyperploidy. 



Hypermorphosis. — This occurs when an animal, in the course 

 of its own ontogeny, passes through the ontogenetic stages of 

 its ancestors but develops beyond the final adult stage of its 

 ancestors ; overstepping. 



Hyperploid. — (i) A heteroploid in which the chromosome 

 number is slightly greater than the nearest multiple of the 

 haploid number, (ii) Having a chromosome number slightly 

 in excess of the nearest multiple of the basic number. See also 

 Sectional Hyperploidy and Hyperdiploidy. 



Hypertely. — (i) The evolution of unduly large individuals, 

 or parts of individuals, (ii) Mimetic adaptation which has 

 passed beyond close resemblance. 



Hyphal Aversion. — A form of incompatibility, in fungi, in 

 which the hyphae of incompatible strains cease growing or 

 reverse their direction of growth whenever they approach to 

 within a few millimetres of each other. 



Hypnosis. — The dormancy of seeds. 



Hypogenesis. — (i) Asexual development, (ii) Similarity of 

 appearance (or function) acquired independently, but at differ- 

 ent periods, by unrelated forms. Adj. Hypogenetic, cj. Gei- 

 tonogenesis. 



Hypomorphic (Mutation). — A gene mutation producing an 

 efifect similar to but not so great as, that produced by a gene 

 loss (deletion) (J. Heredity). 



Hypophysectomise. — To excise the pituitary gland. 



Hypophysectomy. — Excision of the pituitary gland. 



Hypophysis. — The pituitary, a ductless gland situated at the 

 base of the brain. The anterior lobe of the pituitary secretes 

 a hormone which (o) governs, in the female, follicular matura- 

 tion, ovulation and the formation of luteal tissue, and, in the 

 male, the development of the testes and spermatogenesis; and 

 (6) controls the production of hormones by the gonads. 



Hypoploid. — Lacking one chromosome of the complement. 

 See Haplo-. 



Hypostasis. — Non-allelomorphic recessiveness. See Epistasis. 



