APPliNDlX I 



Sex-Limited, of the Inheritance of differences which are expressed in 

 one sex only or at least in the two sexes differently. Morgan 1914. 



Sex-Linkage, v. Linkage. 



Sex Ratio, the ratio of numbers of the two sexes at conception, at birth, 

 at a given age or in the total population, usually expressed in terms 

 of the females as 100. 



Sex-IIeversal, the change of a mature or nearly mature individual from 

 having the appearance or function of one sex to having the appear- 

 ance or function of the other, v. Intersex. 



Sexual Isolation, genetic isolation by the sexual mechanism, v. Isolation. 

 Dobzhansky 1937. 



Sexual Reproduction, v. Reproduction. 



Sib(s) or Sibling (s), progeny of the same parents derived from different 



eggs- 

 Sib Mating, the mating of sibs. 

 SiGNincANCE, the measure of reUability of a difference between obser- 

 vation and expectation. A difference is said to be Signthcant if, on 

 the hypothesis being tested, the probability of obtaining one as large 

 or larger is lower than some chosen level, termed the Level of 



SiGNinCANCE. 



Test of Significance, a test designed to assess significance, and so to 

 distinguish differences due to samphng error from differences indi- 

 cating discrepancies between observation and hypothesis. 

 Simplex, v. NuUiplex. 



Skewness, asymmetry in a Frequency Distribution. 

 Somatic, of all parts of an individual except, in planes, Germ Mother 

 Cells or, in animals. Germ Track cells. 



Somatic Crossing-Over, v. Crossing-over. 



Somatic Mutation, v. Mutation. 



Somatic Pairing, v. Pairing. 

 Species, in Sexually Reproducing organisms, a maximum interbreeding 

 or potentially interbreeding group, breeding true within its own 

 limits in nature, v. Apomixis, Breed, Caste, Clone, Race, Stock, 

 Strain and Variety. Ray 1670. 



The classification into the next three {Turesson 1922) is based on 

 ecological adaptation of groups of individuals of decreasing 

 importance. 



Coeno-Species, incapable of genetic recombination with other similar 

 units. 



Eco-Species, capable of genetic recombination with other similar units, 

 but hable to reduced fitness or fertility from it. 



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