186 INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



showed the following marks of weak development: (1) the head is not quite erect, 

 but has a noticeable cant to one side; (2) the back of the head is rather too large for 

 the fore part; (3) a median crease, or division between the feathers of the breast, 

 has never wholly disappeared, as it normally does Avith young birds becoming adult; 

 (4) this bird has shown for a short time each season a desire to mate, but he has not 

 been as energetic and persistent as perfect hybrids are. 



Wnj neck, complete lack of coordination of head and limbs. — ^A young hybrid 

 (0 6-SO 2-B) hatched June 14, 1908, from a cross of a male T. orientalis (66) 

 and female risoria x orientalis hybrid (2). It died at the age of only 5 weeks and 3 

 days. This bird showed deformities as follows: (1) the neck began to be bent to one 

 side (left), the head being held with beak turned to the right; (2) the left eye (lower) 

 seemed to be blind some time before death; (3) the legs sprawled apart and soon 

 became of no service, the bird usually lying on its ventral surface supported by one 

 or the other wing, the head usually resting on the floor; (4) the bird had to be fed 

 by hand after about 10 days, since its head was so twisted that it could obtain no 

 food from the old birds. It became quite accustomed to my feeding it and was 

 quite eager for its food. In trying to move, however, the bird could only flop 

 around, much as a headless fowl. It was utterly incapable of a single normal move- 

 ment, except that it would open its mouth widely for food when I grasped its bill. 

 The bird was faithfully fed along with a young white-faced pigeon. (5) It was 

 dolicocephalic; the back of the head was prominent and bulging like the hybrid of 

 1906, referred to above. The wings were symmetrically developed, as was also 

 the beak. 



Here we see a distortion in the neck growing worse day by da.y until the end. 

 The system of developmental processes is, at the beginning, a little unbalanced; 

 later the distortion increases. The "character" is not then a "unit" at first, but 

 something induced probably by weak organization. 



Cross-bill. — The crossed-bill has been seen in several juvenal common pigeons; 

 the curvature in one case amounted to nearly 90°. This deformitj^ becomes visible a 

 day or two afterbirth, but in some cases is already well-marked a few days before birth, 

 as I learned through the following case : The second egg of a pair of hybrids (namely, 

 turtiir X orientalis x homer x ring) was laid July 9, 1908, and failed to hatch; 

 after waiting an extra day I opened the shell and found the bird dead, but developed 

 up to within about 2 days of the time to hatch. This bird showed a quite definite 

 curvature in the upper mandible, which turned to the left.'* 



Infertility. — Developmental processes run on to different lengths. If equilibrium 

 is disturbed, the deflection may become worse and worse — the deformity, being a 

 local weakness, becomes less and less capable of veering to the normal. Do 

 developmental processes run on continuousbj? An affirmative answer is given as 

 a result of pulling out some of the first feathers prematurely. The color-pattern is 

 thus found to have made progress in the feathers that follow. 



Developmental processes may be arrested by cold or otherwise. May the 

 same process run to different lengths, according to the greater or less strength or 



"In 1911 the editor recorded two cases of "curved-bill" — not certain whether "crossed" — in two iniJialrhcil 

 birds from a mating of a male <S/. alba and a female alba-orientalis hybrid. Since that time a considerable number 

 of cases of true "cross-bill" have been observed in various hybrids. — Editor. 



