240 



Heredity and Eugenics 



'Normal" range of variation. 

 Mode. 



FIG. 77. Diagrammatic representation of the results obtained in the effort 

 to create albinic and melanic races by selection. Shows also the inability of quanti- 

 tative accumulations to carry the modification beyond the normal range of 

 variation, and also the rapidity with which races so created revert to the normal 

 standard when the selective influence is removed. 



