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R. M. STRONG. 



as well as varieties of pigeons, which Professor Whitman obtained, 

 did not ' encourage the growth of Mendelian ideas. Further- 

 more, his experience was largely with F! hybrids as has been the 

 case with other workers in crossing species of birds. Though 

 sceptical of the importance of Mendel's law, he thought it worth 

 while to make a test of it with birds. 



Professor Whitman was profoundly impressed with the 

 importance of ancestry and pureness of stock in breeding experi- 



FIG. i. From a photograph of a male white ring-dove and a female blond 

 ring-dove. The sexes are alike, and hybrids between the blond and white ring- 

 doves are practically not distinguishable from the above. This picture may be 

 used consequently to represent both "pure" and hybrid birds of either sex. 



ments. As domestic races of animals did not satisfy his ideals 

 in these respects, he naturally turned to wild species for material. 

 Unfortunately for statistical work, wild species do not breed 

 freely in captivity, and hybrids are obtained with difficulty. 

 Standing in a sense between wild species and domestic races of 

 birds in breeding possibilities are the tame ring-doves which are 

 commonly kept in cages. Professor Whitman had found 



