HEEEDITY 



it start^T C. B. Davenport lias also produced 

 much ^evidence favoring the idea of varying 

 potency of characters in recent papers based 

 on'fiis extensive studies on poultry. 

 ^'The case which I described in 1905 was one 

 in which unusual potency seemed to inhere in 

 the gametes of a recessive individual, — one 

 which apparently did not possess the character 

 whose dominance was affected. But there occur 

 also cases in which the varying gametic potency 

 is associated directly with the character af- 

 fected. One such I was able to describe in 

 1906, — that of an extra toe in guinea-pigs. It 

 was found while building up a polydactylous 

 race by selection and crossing it with other 

 races that individuals varied in the potency 

 which the character had in their gametes. In 

 general the better developed the character was 

 in an individual the more strongly was it trans- 

 mitted, i. e. the larger was the proportion of 

 polydactylous individuals produced in crosses. 

 In no case, however, was this a recognizable 

 Mendelian proportion, though both dominance 

 and segregation seemed to be taking place. 

 Variation in potency was, however, unmistak- 



100 



