240 



Heredity and Eiigeiiies 



'Normal" range of vari.Ttion, 



Fig. 77. — Diagrammatic representation of the results obtained in the eitort 

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

 tative accumulations to carry the modification beyond tlie normal range of 

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

 standard when the selecti\-e influence is remo\'ed. 



