APPENDIX I 



Homozygous, of a homozygotc. Batcson 1902. 



Homozygous Sex, Homogametic Sex. 

 Hybrid, Hetcrozygote or Heterozygous. Usually used where chromo- 

 some or multiple gene differences are concerned. Cf. Heterokaryosis. 

 Inversion Hybrid, hybrid for inversion of a segment not including 



the centromere. Darlington 1937. 

 Numerical Hybrid, one whose parental gametes differed in respect 



of the number of chromosomes. Darlington 1932. 

 Structural Hybrid, one whose parental gametes differed in respect of 



the arrangement of their genes, Darlington 1929. 

 Hybridization, the production of a hybrid by crossing two individuals 



of unlike genetic constitution. Usually appHed to wide crosses. 

 Hybrid Vigour, v. Heterosis. 

 Hypermorph, v. Amorph. 

 Hyperploids, diploids with an extra piece or pieces of chromosome 



included in their complement. Muller 1932. 

 Hyperpolyploids, polyploids in which one or more chromosomes are 



added to the complete chromosome sets (hyper triploids, etc.). 



Winkler 1916. 

 Hypomorph, v. Amorph. 

 Hypoploids, diploids lacking a piece or pieces of chromosomes from 



their complement. Midler 1932. 

 Hypopolyploids, polyploids in which one or more chromosomes are 



subtracted from the complete chromosome sets (hypotriploid, etc.). 



Winkler 191 6. 



Hysteresis, a lag in the movement at one level in response to stress at 

 another level, e.g. in the adjustment of the external form of a 

 chromosome to its internal stresses during the spiralization cycle, 

 Darlington 1935. 



Identical Twins, Monozygotic Twins. 



Idioplasm, Germ Plasm. Nageli 1884. 



Inbreeding, the raising of progeny by the mating of two more closely 

 related gametes or zygotes, as opposed to Outbreeding from the 

 mating of two less related gametes or zygotes. 

 Inbreeding Coefficient, a measure of the intensity of inbreeding. Pearl 

 1917. 



Incest (in man), breeding between individuals related in degrees pro- 

 hibited by custom, tabu or canonical injunction. 



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