BREWSTER’S WARBLER. 75 
A homogeneous brood of leucobronchiales, like the other brood of mixed 
parentage I studied, might be the progeny of an F’, leucobronchialis, PW Pw, 
mated with a pure chrysoptera or of a pure leucobronchialis, PW PW, (if there be 
such a thing') mated with any chrysoptera. Or it is possible that the homoge- 
neity 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 records. Mr. Chap- 
man’s case (No. 1, p. 68) of pinus @ mated with leucobronchialis 2 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). Lawrencei 2 with a leucobronchialis juv. The 
father in this case was probably a leucobronchialis. 
pw pw X Pw pW 
| 
pinus, chryso., leuco., 
lawrencet, in equal nos. 
If a pure leucobronchialis (PW PW) all the young should be leucobronchiales. 
Fisher, (case 2, p. 70). Chrysoptera 2 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 pinus 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 [lewcobronchialis?]. 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 
lawrencetz. 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 
1A pure leucobronchialis, PW, in the Mendelian sense, must be the offspring of a pair of leucobronchi- 
ales, a conjunction never yet observed. 
