R. C. Pdnnett and p. Q. Bailey 



27 



In general build and habit the -^i $ $ were all remarkably alike 

 (cf. PL IV, fig. 3). Of the F^ cocks there were two classes, viz. those with 

 henny plumage (PI. IV, fig. 2), and those with normal plumage. Within 

 each class however the individual members were very similar to one 

 another. The difference in plumage was not found to be correlated 

 with any size difference either in Fi or in subsequent generations. The 

 Fi birds then from this cross were rather smaller than the pure Ham- 

 burghs, though of course very much larger than the Sebrights. Of 

 these Fi birds 13 were bred from, viz. 1 J' J' and 6 $ $. Most of them 

 were mated with one another but 2 (/J' were run respectively with 

 Gold Sebright $ $ (p. 30) and with 2 i^, $ $ fi-om a bantam x White 

 Leghorn cross (p. 31). The figure below provides a concise scheme of 

 the experiments. 



Sebright ? x Hamburgh i 



I 



, , . , 1 , 



Fii X Fi i 



(Pens 21- 25, 



1912—13) 



F2t X F2S 



FiS X Gold Sebright ? ? 

 (Pen 7, 1911) 



i X S 



FiS x2Fi'i $ (Bantam x 



White-Leghorn) 



Pen 4, 1911 



? X <? 



The Fo generation. During 1912 and 1913 five pens of Fi birds were 

 bred from. Each of these contained a single pair, except that in 1912 

 one of the F-i cocks was run with two of his sisters. We have analysed 

 the results given by each pen separately, but they are very imiforni, 

 and as we can detect no significant difference we shall consider them 

 together. In all we have raised 233 F„ birds to maturity, viz. 112 J" jf 

 and 121 %%■ In both sexes the range of size is very considerable. 

 The {/(/ vary from 680 — 1420 grams while the pullets weigh from 

 540 — 1290 grams. Allowing for sexual difference the range of variation 

 is evidently similar in the two cases, and in each of them the weight of 

 the largest bird is distinctly more than double the weight of the smallest. 

 For each sex also the range of variation is such that the smallest birds 

 are smaller than the Silver Sebright bantam, while the largest are larger 

 than the Gold Hamburgh. 



