INHERITANCE OF PLUMAGE-COLOR. 15 



to obtain from four or five broods one "Ausstich," /. e., a beautifully "marked" 

 bird. Here also is it very important that two pure-bred birds be mated, e. g., a 

 beautiful crested green cock with a straw-yellow female; most of the progeny will 

 then resemble the parents, and be likewise uniformly green or yellow: but if a mix- 

 ture of color does occur it will usually be an "Ausstich." Such "Ausstichvogel" 

 are used .... for the production of rare markings. Green and Isabella colors do 

 not mix, /. e., these two colors do not occur in the same bird ; paired they produce 

 only young which show each color alone. Finally, the following results of crossing 

 seem to have been demonstrated. Black and green capped birds are bred from a 

 male of this sort mated with a pure yellow female; green or black "swallows" from 

 a gray or blackish-green crested male with a non-crested bright-yellow female ; 

 isabella "swallows" from a crested Isabella male with a golden yellow non-crested 

 female, and gray-, green-, and black-crested from a male of the required sort with a 

 bright or a straw-yellow female. 



My own experiments in part confirm these statements, in part 

 disagree with them. These results are as follows : 



a. Green X Green. — When self-greens are mated together all of the 

 offspring are green. I made five matings of this sort (Nos. 402, 404, 

 502, 613, and 624) and obtained 21 green offspring and no other color. 



b. YellowX. Yelloiv. — When self-yellows are mated together all of the 

 offspring are yellow. I made 11 matings of this sort and obtained 34 

 offspring ; all were pure yellow except in 6 cases, where there were 

 tickings of a darker color. These were obtained in Experiments Nos. 

 503 (2), 513 (1), and 606 (3). As to Experiment 606 it should be said 

 that No. 68 (male) used in it, though yellow, had a green crest and a 

 green patch lying off of the crest on the nape of the neck, 



c. Yellow Y. Green. — This cross,* no matter what the ancestry of 

 the colors, invariably gave mottled birds with varying proportions of 

 dark pigment on the yellow background. At one extreme are the 



heavily variegated ' ' birds ; at the other extreme is only a ' ' ticking. ' * 

 The usual result is a "lightly variegated" or unsymmetrically "marked" 

 bird. The distribution of the dark pigment is not wholly at haphazard. 

 Green is usually found in the lateral tail feathers, on the secondaries 

 and wing-coverts of one or both wings. In addition to these areas 

 patches are found on the head, nape, breast, at the base of the circum- 

 anal feathers, between the shoulders, and on the rump. The crossing 

 of yellow and green thus gave me, in disaccord with the statement of 

 Russ above, always the mottled condition (plate 3, fig. 5). 



It now remained to determine the nature of the mottled condi- 

 tion — whether a fixed mosaic or, like the blue color of Andalusian 

 fowls, a heterozygous form or, like mottling in mice, due to a mottling 

 •factor. Consequently, I mated the mottled birds of Fj with each other, 

 with greens, and with yellows. The results of such matings are given 

 in tables 4 and 5. 



♦Experiments 501, 504, 506, 508, 509, 510, 512, 514, 515, 608, 611, 710. 



