ON INHERITANCE OF WEIGHT IN POULTRY. 



By R. C. PUNNETT, M.A., F.R.S., 

 AND P. G. BAILEY, M.A, 



CONTENTS. 



PAOE 



Introduction . 23 



The Hamburgh- Sebright Cross 25 



The F-i generation 27 



The F.| generation 29 



The Hamburgh- Sebright x Brown Leghorn Cross .... 31 



The Hamburgh-Sebrightx (Bantam X White Leghorn) ... 31 



Hypothetical Explanation 33 



Explanation of Plate 39 



Introduction. 



Few experiments have been undertaken with the object of investi- 

 gating the inheritance of size or weight in animals. Beyond the 

 observations of Goldschmidt' and of Phillips- on ducks, and of Castle^ 

 on rabbits practically nothing definite is known. Nor are all of these 

 observations sufficiently extensive to advance our knowledge greatly. 

 Goldschmidt only reared an F.. generation from one cross and that 

 consisted of but 8 individuals. Moreover as his weight records cease 

 at the age of 10 weeks little is to be learned from them that bears 

 upon our present enquiry. Castle's work on the weights of rabbits is 

 too scanty to give much definite information. Phillips' experiments 

 however are more extensive and suggestive. From the cross Mallard x 

 Rouen he reared 13 F^ and 33 ^2 birds. The Fi birds were inter- 

 mediate in size as compared with the parents. The mean of the 

 F„ birds was also near that of the Fi, but their range of variation 

 was considerably greater. None however were as heavy as the Rouen, 

 nor were any as light as the Mallard. The numbers however are too 

 small to be able to state definitely that these classes do not appear in 



1 Zelt.f. iiid. Abst. Vererb. 1913. 2 Journ. Exp. Zool. 1912; ibid. 1914. 



'■> Publ. Cameij. Inst., Wash., No. 114, 1909. 



