APPENDIX I 



KiNETOCHORE, Centromere. Schrader 1938. 



KuRTOSis, the departure of a symmetrical frequency distribution from 



the normal by excess (Platykurtosis) or deficiency (Leptokurtosis) 



in its shoulders as opposed to tails and centre. 



Leptotene, the undivided and unpaired chromosome threads at the 

 earliest stage of the prophase of mciosis, and, by extension, the stage 

 itself. Winiwarter 1900. 



Lethal Gene, a gene whose substitution for its normal allelomorph 

 converts a viable into an inviable gamete or zygote. May be domi- 

 nant or recessive. The expression of the gene may be modified by 

 genotype or environment, and when incomplete in effect the gene 

 is said to be Sub- or Semi- lethal. 

 Balanced Lethal Genes, non-homologous, lethal genes in chromo- 

 somes from opposite gametes. The chromosomes concerned must be 

 homologous except in ring-forming interchange heterozygotes. 

 Midler 191 8. 



Likelihood Function, the function relating an unknown parameter to 

 observations from which it can be estimated. Cf. Probabihty 

 Function. 

 Method of Maximum Likelihood, the method of estimation depending 

 on the maximization of the log likelihood (and hence of the like- 

 hhood) function. Always leads to an Efficient Statistic, and also to 

 a Sufficient Statistic if one exists. 



Lineage, in man a section of a tribe or mating group forming a unit 

 of common descent, with a name inherited in either the male or 

 female line, within which mating is tabu, i.e. forbidden by custom 

 or law. 



Linear Order, v. Chromosome Map. 



Line Breeding, the mating in successive generations of individuals having 

 the same known common ancestor, excluding the closest relationships. 



Linkage, the combination in the cell products of meiosis (spores or 



gametes) of pairs of segregating genes in non-random frequencies 



owing to their presence in the same chromosome or in chromosomes 



associated at meiosis. Morgan 19 11. 



Linkage Map, Chromosome Map, determined by recombination 



relations. 

 Partial Sex Linkage, where the linkage is incomplete, i.e. where the 

 gene lies in the Pairing Segment. DarJiiioton, Haldane and Koller 1934. 

 Sex Linkage, the segregation of a gene in association with the sex 

 inequality. Morgan 19 14. 



Elements of Genetics A.0\ CC 



