SINGI.E-COMB WHITE LEGHORN AND HOUDAN. 



25 



10. Number op Toes. — First hybrid generation . Among 37 individuals the 

 following distribution appears : 



Hurst (190.5, p. 133) got among 105 birds 103 with trace of extra toe 

 (including duplication of nail and hyperphalangia) and two without any such 

 trace. The difference in the proportions of extra and normal toes between 

 Hurst's and my results is partly a matter of classification and perhaps partly 

 due to the real difference in potency of the extra-toe characteristic in the 

 two strains. 



Second hybrid generation. To learn if the individuals with 4-4 toes were 

 merely imperfect dominants or true recessives I mated two of them (Nos, 

 84 9 and 869) with their brother, a 4-toed cock (No. 83 <? ) . Of 23 offspring, 

 17 were normal-toed and 6 had extra toes on one or both feet, or nearly 25 

 per cent with extra toes. Expectation, on the other hand, was either (a) 

 if the 4-4-toed were recessives there should be no extra toes, or else {b) if 

 extra toe here merely fails to dominate there should be 75 per cent with 

 extra toes. Hurst (1905, p. 150) mated together two 4-4-toed hybrids and 

 got 14 extra- toed to 8 normal, or 63.6 per cent extra-toed. He also mated 

 the same 4-4 hybrid cock with a 4-toed Hamburg Cochin hen, and about 

 half the offspring had extra toes. He concludes : " These results prove that 

 the apparently recessive feet with no trace of extra toe .... are in reality 

 DR's, as both birds gave chicks with e. t. when bred together and with pure 

 recessives. ' ' I am inclined to doubt if this is the whole story, for one of my 

 two 4-4-toed hybrid hens, namely. No. 86, mated with 83 $ , gave 12 offspring 

 with 4-4 toes and no certain offspring without normal toes. This looks as 

 though 86 9 and 83 ^ were both truly recessive. No. 84 9 , on the other 

 hand, produces extra-toed and normal-toed individuals in about equal pro- 

 portions. Further experiments with 83, 84, and 86 are planned for 1906. 



Second hybrid {8j$) niated zvith white Leghorn (7/9 )• The father (87) 

 has an extra toe on the left side only. Of 25 offspring 17 have 4 toes 

 on each side, 6 have 5 toes on each side, and 2 have an extra toe on one 

 side only. 



II. Correlation of Characters. — The first hybrids between white 

 Leghorns and Houdans show a fairly constant association of characteristics, 

 a white plumage flecked with black, white mandible, uarrovvish nostrils, 

 Y-shaped comb, muffed and bearded face, reduced crest on a domeless head. 



