INHERITANCE 315 



secondly, racial betterment through breeding the best. (Pages 420- 

 425, 437, 444.) 



Summarizing our survey of inheritance, in the first place, it is 

 evident that the basis of inheritance is in the germinal rather than 

 in the somatic constitution of the individual. A character to be 

 inherited must be represented by one or more genes in the germ 

 cells, although the environment is not unimportant in the develop- 

 ment of the character from the gene complex. Secondly, there is 

 no satisfactory evidence that modifications of the body, ' acquired 

 characters,' can be transferred from the body to the germ complex 

 and so be inherited. And thirdly, the germinal basis of characters, 

 genes, may be dealt with essentially as units. The chromosomes — 

 linkage groups of genes — undergo segregation and independent 

 assortment during the development of the gametes of an indi- 

 vidual, so that paternal and maternal contributions may be re- 

 adjusted in all the possible combinations. Finally, mutations 

 afford still further changes in the gene complex for distribution by 

 the genetic mechanism, and so provide crucial opportunities for 

 variation — for descent with change. 



