5 



Roux (1888). Experiments with frogs' eggs. 

 Distinction between quantitative and qualitative 



nuclear division. 

 The mosaic theory of development. 



De Vries (1889). Intracellular pangenesis. 



Differentiation explained by migration of pan- 

 genes. 



Weismann (1893). Inheritance of acquired char- 

 acters denied. 

 Dynamical and pangenesis theories rejected. 

 Variations due to changes in the germplasm. 

 Amphimixis, the mingling of germplasms. 

 Id, the unit of germplasm. 

 The id composed of determinants. 

 Biophor, the unit of protoplasm. 

 Migration of biophors. 



The process of ontogeny. 



Division of the id. 

 Division of determinants. 

 Qualitative and quantitative divisions. 

 Reserve germplasm. 



Effect of amphimixis. 



Struggle of the ids causing variation. 

 Homologous determinants. 



Homodynamous. 



Heterodynamous. 

 Variation as the result of new combinations 



of old characters. 



Reversion, 



Sexual dimorphism. 



Regeneration. 



Budding. 



Alternation of generation. 



Preformation of every detail. 



