APPENDIX I 



Variation [cotitiimed) 



Continuous variation is not to be taken to imply continuous differences 



in the genotype, since statistical analysis may reveal discontinuities 



in the determinants, v. Polygenes, Quantitative Inheritance. 

 Variegation, the deprivation of a part of the normally green cells of 



a plant of their chlorophyll through the action of a marginal genotype, 



somatic mutation or infection, v. Plastogene. 

 Variety, a sub-division of a species owing its uniformity either to Genetic 



Isolation in nature, or to artificial propagation in cultivation (where 



a variety is often a Clone), v. Breed. 

 Vegetative Propagation (Reproduction), reproduction of the higher 



plants otherwise than by seed, either naturally (runners, bulbs, 



viviparous bulbils, etc.) or artificially (cuttings, grafts, etc.). 

 Viability, Measure of, the number of individuals surviving in one class 



relative to another, standard, class. 

 ViciNiSM, unexpected outcrossing. Balls 1922. 

 Virus, an ultra-microscopic particle whose reproduction in the cell and 



transmission by natural infection gives characteristic reactions of cells 



and individuals. Cf. Plasmagene. 

 ViviPARY, the release of offspring by the mother free from her membranes 



(as in egg or seed). In animals due to delayed egg-laying, in plants 



due to precocious germination and (usually) apomixis. 



W Chromosome, sometimes used for the X chromosome, where the 



female is the Heterogametic Sex. 

 Weight, a differential value assigned to an estimate of a quantity, relative 



to other estimates of the same quantity, for purposes of combining 



the estimates. Usually its Invariance or Amount of Information is 



taken as the weight for each estimate of a series. 

 Wild Type, of an organism or gene of the type predominating in the 



wild population. 



X, Basic Number. 



X Chromosome, with diploid sex differentiation, the sex chromosome 

 in regard to which one sex is homozygous (the Homogametic Sex). 

 With haploid sex differentiation (Bryophyta, etc.), the sex chromo- 

 some of the Female. 

 Attached X Chromosomes, where the two X's of a female are fused 

 at their terminal centromeres and so act as one mechanical unit in 

 inheritance (in Drosophila mclaiwgaster). L. V. Morgan 1922. 



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