Modification of Germinal Constitution of Organisms 243 



"Normal Range of Variation" 



Classes 23 22 21 20 19 18 17 16 IS 14 13 12 11 10 9 8 7 6 5 4 3 2 1 a. b. c, d. e. f g. h. 



Fig. 79. — Diagranimatic rcpresentalion of the rcsuUs obtaim.-d in the creation 

 of albinic and melanic races by the combined infjucnce of selection and en\-iron- 

 mental stimuli. These experiments show a difference from the results shown in 

 some of the former diagrams, in that there are a number of extreme variations 

 produced which apparently are stable in several successive generations; however, 

 when the selective effect is removed the divergent race is seen not to be stable and 

 to revert with considerable rapidity to the mediocre or parental stock. 



