14 HEREDITY. 



does this discussion persist in the camps of the students of 

 Eugenics. In mankind some would have us believe that the 

 inherited only determined a child's character and peculiarities, 

 others look upon men as bom equal and different only according 

 to the environment in which they grew up. 



As soon as we leave the "determinant" view of inheritance, 

 and place ourselves upon a biomechanical standpoint it be- 

 comes evident that the controversy is absurd. In so far as the 

 development of an individual and therefore its characters can 

 be said to result from separate factors in the development, these 

 factors can be shown to be of two fundamentally different 

 kinds, inherited ones, genes, which affect the devdopment from 

 within, and non-inherited ones, which influence the develop- 

 ment from without. We would not be willing to say, that the 

 inherited -factors have a more determining influence on the 

 final qualities of the organisms. It is believed by a group of 

 authors, that variation in the set of inherited factors must 

 necessarily translate itself into a discontinuous variability, and 

 that variation in the environment must result in a continuous 

 variation. In the following chapter we will try to show that 

 there are cases of continuous variation caused by discontinuous 

 differences in the genotype, and on the other hand, cases of 

 discontinous modification, caused by differences in the envir- 

 onment. If now we turn our attention to the nature of the 

 genes, those things which are inherited, and which often are 

 factors in the development of the organisms, we see, that all 

 the most diverse, older theories of inheritance resemble each 

 other in one point, they all agree that each gene is made of 

 protoplasm, and must multiply by bi-partition. It matters not 

 whether we examine Darwin's pangens, or the pangens of de 

 Vries, that are differently conceived, or Weismann's determi- 

 nants or biophores, the biological molecules of Dewar and Firm, 

 the bacteria of le Dantec and the brothers Simpson, or even the 

 modem loci of Morgan and the cytologists, in every single case 

 a gene is thought to be composed of protoplasm and to multi- 

 ply by bi-partition. 



