17 



Heritages that are mutually exclusive. 



Eye-colors : (Galton, pp. 1 38-1 53 and 212- 

 218.) 



Division into light and dark. 

 Distribution in the family. 



When F has peculiarity D, his sons (S) will 

 have 1-3 D, each of his parents (G) will have 

 1-3 D, each of his grandparents (Gg) will 

 have 1-9 D, etc. 



Inheritance as limited to sex. 



Prepotency. 



Reversion, or Atavism : 



In pure breeds. 



In crossed varieties and species. 



Bud reversion. 



In different parts of the same animal. 



Latent characters. 



Appearance in the children of characters not 

 found in either parent. 



Kinds of characters that may be transmitted. 



Telegony. 



iv. Theories of Heredity and Development. 



(Lloyd Morgan, Animal Life and Intelligence, pp. 130-176; 

 Thomson, The History and Theory of Heredity, Proc. Royai 

 Society, Edinburgh, 1889, Vol. 16, pp. 91-116; Darwin, Ani- 

 mals and Plants under Domestication, 2d. Ed., Vol. 2, pp. 

 349-399; Brooks, Heredity; Weismann, Essays upon He- 

 redity; Weismann, The Germ-plasm; Romanes, An E.xamin- 

 ation of Weismannism ; O. Hertwig, The Cell, 1S95 ; O. 

 Hertwig, Zeit- und Streitfragen der Biologic, L Prjiformation 

 oder Epigenese? also trans, under title. The Biological Prob- 

 lem of To-Day; Driesch, Analytische Theorie der Organ- 

 ischen Entwicklung, Leipzig, 1894; Delage, Heredite, Paris, 

 1895, pp. 403-813; Wilson, The Cell in Development and 

 Inheritance, 1896.) 



Requirements of a theory of heredity. 



A theory of heredity must be also a theory of 

 development. 



