98 INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



were the germs of these birds capable of any development. The early part of the 

 season, after a long rest, too, was the time of greatest fertility. Not a single young 

 was reared from 28 tests (table 74). 



It was shown above that a selection of the blackest progeny of dark homers 

 for brother-and-sister matings did not lead to the production of darker progeny, 

 but to a majority of offspring of lighter or redder color than parents or grand- 

 parents; it was indicated also that weakening effects (inbreeding, etc.) were 

 responsible, in part at least, for this result. 



The reverse of the above experiment was also studied. In this experiment 

 light-colored homers (few chequers and small bars) were selected as parents in 

 an effort to obtain offspring of still lighter color. This effort was successful 

 (Chapter II, Vol. I). Table 75 shows, however, that it succeeded best when sire 

 (darker of original parents) was mated to daughter (lightest and narrowest bars) , and 

 from eggs laid late in the autumn (August and November); 3 of the 4 eggs then 

 produced gave rise to birds with weaker bars than had any of their known ancestors. 9 

 This situation, moreover, was continued in the succeeding germs which were laid 

 "out of season." Two photographs (pi. 16) assist in making clear the measure of 

 success attained in this experiment. In the first mating listed in table 75 the parents 

 were unrelated; the lightest colored young of this mating developed from eggs 

 laid outside of the usual breeding season, during autumn and winter. 



Another mating for a period of 5 years was made in the effort to produce 2- 

 barred homers from 3-barred parents one of whom had chequers as well as 3 bars. 



9 The fourth had bars equal to the least developed bars of a parent, and was of lighter color. 



EXPLANATION OF PLATE 16. 



A. Two juvenal homers, brother and sister to the pair figured below. Hatched from a clutch (H 1 



and H 2) just preceding young of fig. B; also the parents of these two pairs of young. 



On the extreme left is H I in juvenal plumage; it presents another distinct step towards the complete obliteration 

 of the bars of the wings and also of the tail. This bird has a typical homer build or form, but has a single feather 

 turned outward (frill-like) in the middle of the upper breast. The ground-color is a distinct shade lighter than the 

 ordinary rock-gray. Head and neck decidedly lighter than in rocks, a shade of rusty brownish in the neck. In place 

 of the subapical black band in the tail there is a very pale whitish-gray band, about 17 mm. in width, with an apical 

 dusky-gray border about 7 mm. in width. Rump whitish gray. 



The wing-bars have lost the black almost wholly, leaving a paler gray than in the rest of the wing; and this 

 paler gray is lightly touched with brownish and bordered posteriorly with a narrow, ill-defined dusky line, varying 

 from 1 to 2 mm. in width. Both bars are in essentially the same condition, but we may note that in the posterior 

 bar the black is practically a faint trace of brownish. In the tertials this posterior bar is nearly of the same color as 

 the anterior bar, but on the inner 3 or 4 tertials 2 to 3 dusky "fundamental bars" cross the outer web of the feathers. 

 This bird makes a near approach to complete Ions of u'ing-bars. At a little distance it appears to have no bars, or only 

 shadowy indications of lost bars. 



On the extreme right is // J; it is clear rock-gray in color, and has narrow black bars about the same as its mother. 

 It has the usual subapical tail-band; the rump is white. The anterior bar has a width of 9 nun. on the inner coverts 

 and gradually narrows to "> mm. just below the middle of the row of coverts. The posterior bar (on (i inner tertials i 

 has a greatest width of 17 mm. on the fourth tertial; it becomes freckled witli gray on the seventh tertial and is nearly 

 obliterated on the eighth. 



The two parents are shown at the center of the figure. 



B. Juvenal homers (7 1 and / 2) with light color (in 7 1) and with wing-bars reduced. Photographed 



.Ian. 19, 1910, at the age of 6 weeks 4 days. 



These birds from sire mated to daughter (table 75), and from eggs laid in very laic autumn, Nov. 15 to 17, 1909. 



Juvenal 7 / (on left) has rock-gray color with four squarish black spots on the outer web of the inner tertials. 

 The first and fourth spols are a little smaller and weaker or thinner than the second and third, which measure 10 by 

 8 mm. and 13 by 8 mm., respectively. Below these spots there are only scattered freckles which are too weak to figure 

 as spots. The appearance is thus practically what we see in the stock-dove (('. i/vmxi. The anterior bar has no spots, 

 but just freckles enough to indicate a trace of a bar when closely examined. 



Juvenal 7 2, color almost white or silver gray. 



