No. 559] BARRED PLUMAGE PATTERN 



425 



b 2 FfL 



forming gametes 



bFi ■ bFi. 



The mating then becomes 



W. L. Bfl Bfl 

 B.H. bFi bFi 



B b f 2 Ii = white JJ, heterozygous, for barring and inhibiting factor. 

 BbFfIi = white ?$, heterozygous, for barring and inhibiting factor. 



In other words, the ¥ 1 from mating of W. L. $ X B. 

 H. $ gives birds that are all white, but heterozygous for 

 B and /. The fact that some Fj birds put up barred 

 feathers may be explained on the ground that the domi- 

 nance of the inhibiting factor (I), in heterozygous con- 

 dition, was not complete. Where a little black was per- 

 mitted to show, there it filled the pattern of an already 

 barred feather. 



What now takes place when the Fj whites are mated 

 among themselves? The Fj males with the zygotic con- 

 stitution Bbffli form gametes Bfl Bfi bfl bfi. The F, 

 females with the zygotic constitution Bb Ff Ii form 

 gametes Bfl bFi Bfi bFI. The mating of the F, stock 

 may therefore be represented: 



c? Bfl . bfi . Bfi . bfl 

 $ Bfl . bFi . Bfi . bFI giving in F 2 



'BjX (1) White, homozygous for B and J. 

 Bbfji (2) White, heterozygous for B and I. 

 Bjji (2) White, homozygous for B; heterozygous for I. 

 Bbf 2 I 2 (1) White, heterozygous for B ; homozygous for 1. 

 Bbf^ (1) Barred, heterozygous for B; no I. 

 BJih (1) Barred, homozygous for B; no I. 

 Bb Ff Ii (2) White, heterozygous for B and /. 

 bb Ff i 2 (1) Black, no B nor 7. 



Bb Ff I a (1) White, heterozygous for B; homozygous for I. 



bb Ff Ii (2) White; no B; heterozygous for /. 



Bb Ff it (1) Barred, heterozygous; no 7. 



bb Ff I 2 (1) White, no B; homozygous for 7. 



The data presented above may be summarized as fol- 

 lows: 



