MEXDELIAN EXPERIMEXTS ON FOWLS. 355 



here we have one black, one grey, and one reddish brown. The 

 recessive character therefore appears in different degrees in 

 different individuals, and the fact that the black hen has some 

 Avhite on its feathers shows that the segregation is not complete 

 and the recessive character not perfectly puie. 



The pile birds, both cocks and hens, were soon after Oct. 9th 

 separated from the rest, and on Nov. 20th I examined the hens 

 which were not pile, in order to satisfy myself whether there 

 were any pure dominants, i. e. white without specks of colour. 

 Of Lot A there were none without some lacing to the feathers, as 

 seen from the observations of Oct. 9th, given above. Of the six in 

 Lot B which were not deeply coloured nor pile, there was not one 

 without some trace of colour. Three of them showed slight 

 lacing of colour on the neck-feathers, and all except one of these 

 had a few black or grey specks. 



According to these results, then, thei^ewere no pure dominants 

 either in Lot A or Lot B of the F, generation. Two hens in 

 Lot A had ver}^ pale lacing. In the cocks of this lot there were 

 all degrees of intensity in the red coloui- of the pile. In Lot B 

 there was one cock which was not a proper pile, but had spots of 

 orange and black on its back, and six hens with either a trace of 

 lacing or some specks of colour. If these six hens in Lot B are 

 to be regarded as pure dominants, we have six ont of 17 or nearly 

 one in three instead of one in four. This may seem a good 

 approximation to the theoretical proportion, but it is unlikely 

 that .all the dominants should be female. The fact, however, is 

 that none of these birds w^ere without evidence of colour, and 

 therefore it cannot be said that there Avas complete and clear-cut 

 segregation. 



As I was unable to make mnny further experiments with these 

 birds of the F., generation, I decided to mate some of the hens 

 with least colour with another black-red cock to see if they 

 behaved as heterozygotes or as pure dominants. Accordingly 

 two of the F^ hens above described with least traces of colour 

 were mated in March 1921 with a hankiva (black-red) cock which 

 was among the birds at that time alive in the Zoological Gardens. 

 From this mating nine offspring were produced and reared. As 

 there were traces of colour in the female parents, and some of the 

 Fj hens were also wdiite with black ticks, I thought it possible 

 that these F,, hens would behave as heterozygotes, and not as pure 

 dominants. I therefore i-ather expected that half the chicks 

 would develop into piles and half into black-reds. All the nine 

 chicks obtained, however, developed in mature plumage into fairly 

 typical piles. There were five cocks and four hens, onl}^ one 

 cock and one hen having somewhat paler colour than the rest. 



Although the number of chicks obtained is small, I am of 

 opinion that the F„ hens behaved genetically as dominant: if they 

 had behaved as heterozygotes, I think there would have been at 

 least one, and probably more than one, black-red among the 

 offspring, the theoretical explanation being, of course, half the 



