250 MR. J. T. CUNNINGHAM ON 



all of them with normal toes, all those with the extra toe having 

 been killed ofl". From these were hatched and reared in 1907 

 5 Fg's (2 cocks and 3 hens), and in 1908 8 F/s (3 cocks and 5 hens). 

 In all these cocks the Japanese character of the tail was observed, 

 although they were not all kept long enough to develop any 

 afi-eat leneth of feathers. The result, however, is not conclusive 

 with regard to segregation or absence of segregation m the tail 

 character, for the F^ cock bred from F^ $ and Japanese d might 

 itself have been a pure dominant in this character, in which 

 case all the F^'s would have been either homozygous or hetero- 

 zygous dominants. Similarly, the Fg c? kept for breeding might 

 have been a homozygous dominant, and segregation would then 

 not be evident in F^. A complete experiment to test the segre- 

 gation of the Japanese Long-tail character is therefore yet to be 

 ma le. 



The double hallux did not reappear in any of the Fg or F^ 

 generations, which supports the view that the normal toe in the 

 F./s is a pure recessive. 



II. Incom.])lete Segregation of the Pigmentation of the 

 Silky Fowl 



In Part I. of this paper, when describing the characters of the F.^ 

 generation from a cross between Bankiva male and iSilky female, 1 

 treated the inheritance of the peculiar pigmentation of the Silky 

 as a case of simple segregation. When I wrote that part, I had 

 only examined the F.^ birds in the living condition, in which there is 

 a conspicuous contrast between the sooty colour of the combs and 

 wattles in the majority and the blood-red colour of the others 

 which seemed obviously recessives. Afterwards it occurred to me 

 that if there were incomplete segregation in the colour of the 

 plumage the recessives in other characters also might be impure. 

 I was led to consider the possibility of slight degrees of body 

 pigmentation by the description of such degrees given by 

 Bateson and Punnett in their recent paper in the ' Joxniial 

 of Genetics,' vol. i. no. B. Accordingly I killed No. 10 of the 

 F^'s, which had the white colour and silky character in its 

 plumage, and apparently normal colour in comb and skin, that 

 is to say the comb etc. was blood-red, and the skin, so far as 

 could be seen between the feathers, unpigmented. Before the 

 bird was plucked, however, I noticed a ring of dark colour on the 

 lips of the cloacal aperture. On further examination I found 

 considerable pigmentation of the subcutaneous tissue of the 

 abdomen behind the sternum, which was the cause of the 

 darkening, above mentioned, of the lips of the cloaca. There was 

 subcutaneous pigment on the tarsal joint and all down the tarso- 

 metatarsus, but none on the knee-joint. It occuired also on the 

 elbow-joint of the wing and on the wrist-joint, but not at the 

 shoulder -joint. In all these cases the pigment was visible 

 externally as a darkening of the skin, and under the microscope 



