BREWSTER'S ^Yx\RBLER. ' 75 



A homogeneous brood of leucobronchiales, like the other brood of mLxed 

 parentage I studied, might be the progeny of an Fj Icucobronchialis, PW Pw, 

 mated with a pure chry so ptera or of a pure leucobronchialis, PW PW, (if there be 

 such a thing') mated with any chrysoptera. Or it is possible that the homoge- 

 neitj^ of this brood arose from the number of young being too small to calculate 

 averages from, or in other words too few to show the possible range of variation. 



Other instances of the prevalence of the Law of Dominance in the inheri- 

 tance from mixed unions are furnished by the published I'ecords. Mr. Chap- 

 man's case (No. 1, p. 68) of pinus cf mated with leucobronchialis 9 was pretty 

 well established. Three of the young which were shot June 26 were young 

 pinus, and a leucobronchialis secured in the same spot at a later date Mr. 

 Chapman thinks may have been the remaining bird of this brood. 



Pw pW X Pw 



2 leuco., 2 pinus 

 Brewster, (case 1, p. 70 j. Lawrencei 9 with a leucobronchialis juv. The 

 father in this case was probably a leucobronchialis. 



pw pw X Pw pW 



I 

 pinus, chryso., leuco., 

 lawrencei, in equal nos. 



If a pure leucobronchialis (PW PW) all the young should be leucobronchiales. 



Fisher, (case 2, p. 70). Chrysoptera 9 feeding a young pinus. Another of the 

 young resembled the mother. This may have been a case of an impure 

 chrysoptera (pw pW) mated with an impure pinus (pw Pw) . The offspring 

 in this case should include chrysoptera and pimis in equal proportion. 



Bishop, (case 3, p. 70). Leucobronchialis feeding two young (July 4), ap- 

 parently H. pinus. In one the wing-bars were white, in the other they 

 were broader and light yellow [leucobronchialis'?]. The unknown parent in 

 this case was probably a pinus. Cf. case 1, Chapman, p. 68. 



Dwight, (case 5, p. 71). Pinus feeds young, one of which is pinus another 

 lawrencei. An impure pinus, pw Pw, mated with a lawrencei, pw pw, 

 should produce young pinus and lawrencei in equal numbers, by Mendel's 

 Law. 

 It has been already noted on page 69 that Mr. Sage had the good fortune 



1 A pure leucobronchialis, PW, in the Mendelian sense, must be the offspring of a pair of leucobronchi- 

 ales, a conjunction never yet observed. 



