Messrs Bateson and Punnett, A suggestion as to the nature, &c. 165 



A suggestion as to the nature of the " walnut " comb in Fowls. 

 By W. Bateson, M.A., F.R.S., St John's College, and R. C. Punnett, 

 M.A., Gonville and Caius College. 



[Received 3 June 1905.] 



In Report II to the Evolution Committee of the Roy. Soc., 

 p. 109, we discussed the problem of Malay or " walnut " combs in 

 fowls on the supposition that the four types of comb, viz. single (s), 

 pea (p), rose (r), and " walnut " (rp), are allelomorphic to each 

 other. 



The facts are (1) that rxp gives in F l a zygotic combina- 

 tion rp, which differs in essential features from any other kind of 

 comb, especially in the presence of feathers or hairs on its surface 

 usually disposed as a transverse band. 



(2) That the gametes of this F 1 are of four types, s, r, p, rp, in 

 equal numbers, which is proved by the result of breeding the F x 

 with a single. Similarly F l x F 1 gives an average of 9rp, 3r, 

 3p, Is. 



(3) The rp birds in F 2 ma} 7 then be pure rp ; or they may 

 give off only r and rp ; or only p and rp ; or again they may bear 

 gametes of all four types. We have thus far failed to find any 

 individuals that give only rp and s ; or to distinguish any class 

 as the product of rp x s from those which are the product of 

 rxp. 



The rp gametes were regarded as true examples of gametic 

 synthesis, and the appearance of s, absent from both pure parents, 

 was treated as due to a resolution or break-up of either the r, 

 the p, or both. A much simpler and probably more correct 

 account has since suggested itself, which it is the object of this 

 note to consider. 



This suggestion will be made more intelligible by describing 

 the way in which it was reached. Certain experiments on Primula 

 sinensis made by R. P. Gregory in conjunction with W. Bateson 

 had shown that short ^tyle, or thrum, is dominant to long style, 

 or pin. In addition to these two types a condition is known 

 which, following Darwin, we have called homostyle. In it the 

 anthers are at the level proper to pin, but the style does not pass 

 through them, and the stigma is at the level of the anthers, the 

 whole style having the length proper to the thrum type. The 



