Haberlandt (1877), KoRSCHELDT (1889), position 

 of the nucleus in relation to growth and nutri- 

 tion of the cell. 



Hodge. Ganglion cells. 



BovERi (1889). Fertilization of enucleated frag- 

 ments. 



1 1. Continuity of the germplasm. 



Continuity of germ cells. 



Contrast between pangenesis and continuity of 

 germplasm. 



Owen (1849). Continuity of germ cells. 



Galton (1872, 1876). Stirp. 



Brooks (1876, 1883). Continuity of germ cells 

 and their contained latent gemmules. 



Jager (1869). Continuity of germ-protoplasm 

 which receives flavor and odor substances from 

 the body cells. 



Nussbaum (1888). Continuity of germ cells. 



Weismann (1883). Continuity of germi:)lasm, con- 

 trasted with continuity of germ cells. 

 The germ tract. Diptera, medusae, ascaris. 

 No doubt that there is some form of continuity. 



12. Preformation. 



The theory of continuity leaves unanswered the 



questions of differentiation and variability. 

 The new aspect of the theory of preformation. 



Darwin (1868). Every i')art of the embryo rep- 

 resented in the egg, by one or more gemmules. 



Brooks (1883). Similar theory. 



His (1875). Theory of gemmules rejected. 

 Principle of the differentiation of areas. 

 Principle of iinccpial growth. 



