GENETIC STUDIES IN POULTRY. 



II. INHERITANCE OF EGG-COLOUR AND BROODINESS. 



By R. C. PUNNETT and the late Major P. G. BAILEY, R.F.A. 

 (With 13 Text-figures and Plate IX.) 



Introductory. ' 



In 1910 we started some experiments with the intention of attempting 

 to work out the genetics of egg-colour and of broodiness in poultry. 

 At the time at which they were begun there was a fair prospect of 

 means being found to carry them to a definite conclusion. This prospect 

 was shattered by the advent of war, and the work was gradually curtailed 

 until eventually it had to be abandoned. Nevertheless, the experiments, 

 fragmentary as they are, present some points of interest which seem 

 worthy of being placed on record. 



Few observations concerning the genetics of either egg-colour or 

 broodiness have hitherto been published. Hurst (1905) found on crossing 

 the two non-sitting breeds, White Leghorn and Houdan, that none of 

 the ^1 hens went broody; but that from the cross Black Hamburgh x 

 Buff Cochin the ^i pullets all went broody like the Cochin. With regard 

 to egg-colour he states that from the former cross all the pullets laid 

 only white eggs, while from the Hamburgh-Cochin cross the F^ ^% all 

 laid "eggs of varied hue, none being so brown or so white as the parent 

 breeds." Neither character appears to have been the subject of investi- 

 gation beyond the F^ generation. 



A remarkable account of the mode of transmission of egg-colour was 

 published by Holdefleiss in 1911. He contended, among other things, 

 that the colour of the e^g laid by the hen is affected by the cock that 

 fertilises it: that the hens resulting from a cross between birds belonging 

 to brown- and white-egglaying strains lay both brown and white eggs : 

 and that such F^ hens mated to a brother produce both brown and 

 white eggs in the ratio 3:1. Though we regard Holdefleiss' paper as 

 open to destructive criticism we do not consider it necessary here to do 



