APPENDIX I 



Alternation of Generations, the occurrence of two phases in the hfe 

 cycle corresponding to, or derived from, the haploid and diploid 

 phases of sexual reproduction. Various forms of Apomixis can 

 equalize the chromosome numbers of the two phases. 



Alternative Inheritance, v. Allelomorph. 



Ameiosis, the occurrence of one division of the nucleus in place of the 

 two of a normal Meiosis, leading to Non-Reduction of the mother- 

 cell. 



Amitosis, the division of a nucleus without the appearance of chromo- 

 somes. Originally a misinterpretation. Fkmming 1882. 



Amorph, a recessive mutant gene which has no detectable effect on the 

 characters affected by the non-mutant allelomorph and is indeed 

 equivalent to a mere absence of it. Midler 1932. 

 Similarly for other types of mutant gene : — 

 Antimorph, having an effect contrary to that of the non-mutant 



allemomorph. 

 Hypermorph, having an effect similar to but greater than that of the 



non-mutant allelomorph. 

 Hypomorph, having an effect similar to but less than that of the non- 

 mutant allelomorph. 

 Neomorph, having an effect apparently unrelated to that of the non- 

 mutant allelomorph. 



Amphidiploid, Allotetraploid. v. Allopolyploid. Navashin 1927. 



Amphimixis, reproduction by the fusion of two gametes in fertiUzation. 

 As opposed to Apomixis. Weismann 1891. 



Anaphase, the stage at which daughter centromeres move apart in 

 mitosis and at which co-orientated centromeres move apart in the 

 first division of meiosis. Strasburger 1884. 



Androdioecy, the condition of plant populations or species in which both 

 male [i.e. female sterile) and hermaphrodite individuals are found. 

 Cf. Andromonoecy, Gynodioecy. Darwin 1877. 



Androgenesis, Male Parthenogenesis. Wilson 1928. 



Andromonoecy, the condition of an individual plant or of a species 

 having individuals which bear both male {i.e. female sterile) 

 and hermaphrodite flowers. Cf. Androdioecy, Gynomonoecy. 

 Darti'in 1877. 



Aneuploid, having different chromosomes of the set present in different 

 numbers, through purely numerical aberration and therefore an 

 Unbalanced Polyploid. Cf. Euploid. Tackholm 1922. 



Anisogamy, Heterogamy. 



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