38 THEORY OF ORGANIC EVOLUTION. 



tofore was present as a latent determinant, may 

 develop in the child. But also both parental charac- 

 ters may appear at once and in various combina- 

 tions. Whether the development follows in the 

 one way or the other depends on the strength of 

 the individual determinants, on the kind of their 

 idioplasmic arrangement, and on their agreement 

 with the nature of the newly formed idioplasm. 



l6. HEREDITY AND VARIATION. 



If heredity and variation are denned according 

 to the true nature of organisms, they are only ap- 

 parent opposites. Since idioplasm alone is trans- 

 mitted from one ontogeny to the next following, the 

 phylogenetic development consists solely in the con- 

 tinual progress of the idioplasm and the whole gen- 

 ealogical tree from the primordial drop of plasma 

 up to the organism of the present day (plant or 

 animal) is, strictly speaking, nothing else than an 

 individual consisting of idioplasm, which at each 

 ontogeny forms a new individual body, correspond- 

 ing to its advance. 



In this idioplasmic individual the automatic or 

 perfecting variation is always active, so that the 

 idioplasm of a phylogenetic line always grows by 

 propagation of the determinants contained within 

 it, as a tree grows larger through its whole duration 

 of life by branching. On the other hand the adap- 

 tation variation caused by external stimuli is pres- 



