APPENDIX I 



Sample (Random), a finite scries of observations or individuals taken at 

 random from the hypothetical infinitely large population of potential 

 observations or individuals. 

 Satellite, a short segment of a chromosome, separated from the rest 



by one long constriction if terminal or two if intercalary. 

 Second Division, the second of two divisions of Mciosis, formerly 



known as the homotypic or equation division. 

 Sectorial Chimaera, v. Chimaera. 



Segment, a portion of a chromosome considered as a unit for a given 

 purpose, V. Differential Segment, Pairing Segment, Interchange. 

 Belling 1927. 

 Segregation, separation at meiosis of the chromosomes, or parts of 

 chromosomes such as genes, of paternal and maternal origin. Bateson 

 1902. 



Effective Segregation, that wliich gives viable gametic or zygotic 

 combinations. Darlington 193 1. 



Preferential Segregation, the non-random assortment of a particular 

 chromosome or segment with respect to the four cells produced at 

 meiosis, or to a non-homologous chromosome, or in Polysomics (or 

 Allopolyploids) to a particular homologue. 



Secondary Segregation, the segregation in an allopolyploid of 

 differences between its ultimate diploid parents. Darlington 1928. 



Somatic Segregation, the formation by mitosis of cells differing from 

 one another, either through Mutation or Somatic Crossing-over in the 

 nucleus, or through an unequal assortment of cytoplasmic deter- 

 minants such as is not required by normal differentiation, v. Sport. 

 Selection, i. (statistical) discrimination in sampling or in arrangement. 

 Opposed to randomness. 



2. (biological) any non-random process which will lead to individuals 

 of different genotypes being represented unequally by their progeny 

 in later generations of a population of self-propagating units. Can 

 be Natural or Artihcial. Darwin 1858. Natural Selection is respon- 

 sible for the Survival of the Fittest [Herbert Spencer 1861). 



Mass Selection (in plant and animal breeding), where a group of 

 selected individuals are pooled for breeding purposes. As distin- 

 guished from individual selection. Cf. Le Coutenr 1836. 



Cell Selection, where genetically distinct cells are selected within 

 an individual. Darlington 1937. 



Selection Pressure, the measure of the action of selection in tending 

 to alter the frequency of a gene in a given population. Cf. Mutation 

 Pressure. Wright 1921. 



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