212 Leg-feathering in Poultry 



run with a Hamburgh </ to give 35 f.l. and 21 n.f.l. chicks, expec- 

 tation being 42 : 14. The number of clean-shanked chicks is rather 

 higher than expectation, but we do not know for certain that all of 

 the hens were in constitution AaBb. If one or two were Aabb the 

 excess in the n.f 1. class would be easily accounted for. 



Lastly a Hamburgh-Cochin from Exp. 6 was mated with 12 Leghorn- 

 Houdan $ % (Exp. 13, p. 141). Here again expectation is fl. and n.f.l. 

 in the ratio 3:1. The actual numbers were 195 fl. and 112 n.fl. The 

 considerable excess of n.fl. birds suggests some complication. Possibly 

 some of the potentially fl. birds do not shew the feathering as in 

 % 64 (cf p. 209 above). There is also the possibility that some of the 

 Leghorn-Houdan hens may have carried a factor inhibiting the develop- 

 ment of the leg feathers. This possibility is indicated by some experi- 

 ments of Bonhote. From the Silky as the feathered and the Yokohama 

 as the clean-legged parent he obtained 2Fi birds of which both had 

 clean legs. Bred together this pair gave 24 chicks of which 8 were fl. 

 and 16 were n.fl. If the Silky carried a factor A for feathered leg and 

 the Yokohama an inhibitor factor I, the constitution of the F^ birds 

 might be regarded as Aali. Such birds in F.2 should give fl. and n.fl. 

 in the ratio 3:13. The figures obtained by Bonhote, viz. 16 n.f.l. and 

 8 fl. are not hopelessly out of accord with those expected, viz. 19*5 

 n.fl. : 4'5 f 1., when the smallness of the numbers is taken into account. 



In the only other experiments of this nature with which I am 

 acquainted, those of Cunningham dealing with a Jungle fowl — Silky 

 cross, the birds reared were too few to give a result of much value. 

 The F^ birds had feathered legs, while of 10 F2 birds 9 were fl. and 

 1 was n.fl. 



In so far as our present knowledge of the heredity of leg- feathering 

 goes we may say that in certain crosses it may behave as a simple 

 dominant, though dominance is always incomplete. In breeds with 

 more heavily feathered legs there are grounds for supposing that two 

 factors for leg-feathering may be present. Further, it is possible that 

 some strains of clean-legged birds may carry an inhibitor for the 

 feathered-leg character. The extent of the feathering shews consider- 

 able variation even in birds similarly constituted in respect of the 

 factor or factors for feathered leg. Rarely a potentially leg-feathered 

 bird may fail to shew even traces of the feathering. Probably clean- 

 legged birds will be found in some cases to carry factors, hitherto not 

 identified, which affect the extent to which the feathering is developed. 

 In support of this is the fact that a clean-legged bird, mated with a bird 



