Except for the similarities of the plumage, the male Sebright differs as much from the female as do cocks of other races. The rose comb is very large in the male, small in the female ([plate 4], figs. 3, 4). The wattles also are longer in the male. The cock carries himself erect, as do the males of other breeds. His spurs are well developed and he shows the aggressive behavior of his sex. On the other hand, the shortness of the feathers on the back of the neck (the hackles), the absence of the pointed feathers on the back and rump, and the usual absence of long sickles and other tail-covert feathers make him hen-like. The detailed account of the feathers in these critical regions will be given when comparisons are made with the feathers of the castrated birds ([plate 6] and [plate 8]).
Six males have been successfully operated upon and with one apparent exception have all given the same results. The birds were of somewhat different ages; they had been hatched about July, and were operated upon about November of the same year, when they were either half grown or had nearly reached maturity. At the time of the operation a few feathers were removed from different regions of the body, and the new feathers that regenerated in the course of 3 or 4 weeks showed all the characteristics of those that came in later to replace the juvenile or first adult coat. These regenerated feathers do not, therefore, call for special notice. All of the new feathers were in shape, pattern, and general coloration strikingly different from the original feathers, some of which were at first still present, the old feathers of course showing no change.
After completely molting, the appearance of the birds may be gathered from the photographs ([plate 5]) and from the colored drawings ([plate 1] and [plate 3]). The male now has in all points the plumage of a typical cock-feathered male bird of other breeds. This is startlingly apparent in the hackle, back, rump, sickle, and tail-covert feathers. Instead of the laced feathers that are characteristic of both male and female, the whole upper surface of the bird appears reddish or yellowish, the black marginal edging of the feathers having disappeared. A detailed comparison of the feathers of the different regions will show how great a change has taken place. (See page 8.)
In [plate 6] and [plate 8] the feathers from characteristic regions of the normal Sebright and of the castrated Sebright are shown in pairs.
One of the first Sebrights that was castrated was a lighter bird than the others. Its lighter color was partly due to the narrower outer band of the laced feathers, ([plate 6], figure 1,) and partly to the lighter color of the yellow-brown center of the feathers. The bird had a single comb, but as this crops up occasionally in some stocks of Sebrights, it need not be interpreted to mean that the bird was impure for color factors. After being castrated the bird changed over completely to cock-feathering and has remained in that condition for two or more years. As shown in [plate 5], figure 2, the plumage is even more fully developed than in cock birds of some other breeds. The comb and wattles are, however, shrunken and pale, as in a capon. The bird is timid and scarcely or never crows. When killed (May 1919) no pieces of testes and no trace of testicular tissue at the old situs were found.
The details of the feathers are shown in [plate 6], figures 1 and 1a, where, in each instance, one of the old and one of the new feathers from the same region are placed side by side. The feathers on the head and hackle are yellow, even to the base. At the base of the hackle—the so-called cape—a few feathers have a small black tip. The feathers of the back are entirely yellow, except that where the fluff begins there is some dark pigment. The saddle feathers are for the most part all yellow, but a few have at the base, near the fluff, black on each side. The tail coverts are long, with a black margin at their tip. The tail feathers are long, mossy, and have a black tip. The wing-bow feathers are all yellow, except the black fluff at the base. The feathers on the crop are mostly yellow with black margin around the end. Those on the breast lower down are yellow with black tip and black fluff.
There was another Sebright operated upon at the same time that was a darker bird (as the original feathers show, [plate 8], figs. 1 to 4). It had a rose comb. The feathers that were plucked at the time of operation were replaced at once by new feathers of the cock-feathered type. The new feathers that came in as the old ones were molted were also cock-type, and the bird soon assumed the complete characteristic cock-feathering. The comb was shrunken as in castrated birds ([plate 5], figure 5).
| SEBRIGHT. Plate 6 and 8. | CASTRATE. Plates 6 and 8. | ||
| 1. | On the head (a) the feathers are small, dull black with lighter margin and reddish quill. | 1. | Feathers entirely yellow and more slender. Those on each side of the shrunken comb stand up from the head. |
| 2. | On the hackle (b) the feathers are yellow bordered with black, especially at the base, and at the tip outside of this border there is an arrow yellow border (broader at base). The border is absent at tip. | 2. | Hackles on upper part of neck have a black base with red tip. The outer edge, without barbules, is narrow, then broader than at tip. Farther down the neck the edge with barbules is yellow with a narrow black margin. |
| 3. | In the middle of the back (between the wings) the feathers are yellow with black margin at the tip. At the base there is some dark color. | 3. | In the part of the feather with barbules there is a yellow center bordered by a broad black band, especially at base. In the part without barbules the feathers are yellow and more pointed. This region especially is deeper yellow than in the original Sebright. |
| 4. | The saddle is made up of typical laced feathers with black where the fluff begins. | 4. | Saddle consists of long, slender laced feathers, except at tip, which is red. Barbules are absent along edge of outer third of feather. |
| 5. | The tail coverts are short; the upper ones, especially the short sickles, are slightly curved. The sickle feathers extend up only about half the length of the tail. They are yellow, laced, and have a black margin, tending to be lost at tip. | 5. | Tail coverts long, covering the tail as in cock birds of other breeds. The sickle feathers, especially the upper ones, are much curved, with black tips; the black margin is largely gone. The feathers are mossy, sometimes splotched (this is also sometimes noticeable in normal birds). |
| 6. | The yellow tail is short and erect. | 6. | The tail feathers themselves are almost twice as long as in normal bird; the upper feathers are more curved. |
| 7. | The feathers on the wing bow are practically like those on the back, but shorter. | 7. | The feathers of wing bow are like those of the back of the same bird, but shorter. |
| 8. | Over the crop and lower breast the feathers are laced. | 8. | The crop feathers are narrower, with a wider black margin, and a few may be also entirely black. Feathers on lower breast much like those in normal, but a little more pointed. |
During the spring of 1917 it was noticed that the bird was going back towards the hen-feathered type, and by the end of the summer he was in the intermediate condition, as shown by the photograph and by the individual feathers ([plate 8], 1b, 2b, 3b, 4b). The comb had begun to enlarge also. The bird was opened again (1918) and pieces of testis about as big as peas were found on one side. Evidently a piece of the old testis had been left behind and had regenerated. As it enlarged the new feathers were affected so that the plumage returned towards the normal type. The pieces of testis were removed and a few feathers plucked out. The new feathers that came in were typically cock-feathered, and, as the molting proceeded during the winter and spring, the bird became cock-feathered for a second time as shown in photograph ([plate 5], figure 6) and by the feathers in [plate 8], 1c, 2c, 3c, 4c. Here, then, is an excellent example of the connection between the gonad and the condition of the plumage. On opening this bird (May 1919) no pieces of testes were found. There was a very small whitish lump at the situs of the old testes, which, when sectioned, showed some glandular-like tissue, not in tubules, and no evidence of testicular tissue.
Three other younger Sebrights of the same stock were successfully castrated. They were hatched in June or July and castrated in November of the same year. They remained quite small birds, despite their elongation due to the long tail and tail coverts that they developed. One of these birds in his cock-feathered plumage is shown in [plate 3], figure 1. One has died, the other two are alive and markedly cock-feathered, as shown in [plate 6], figure 2a. All three birds were dark red-brown, much more so than the two preceding cases, especially the first case. This color difference might be attributed to the earlier age of the three birds when operated upon, or to a more complete (or less complete) operation involving perhaps neighboring parts, or to the birds having a somewhat different genetic composition (i. e., modifying factors). There is no special reason why the operation if performed early should have a different result on feathers that develop after the bird is of adult age. Goodale has suggested that there may be organs in the vicinity of the testis that have some influence on the kind of plumage produced, and if there are such organs they might be removed in one bird and accidentally left in another. It would not, however, be probable that the bird operated on at first had received one treatment and the later ones the other treatment. It seems to me more probable that the birds have come from different genetic strains, and that this genetic difference gives a more plausible explanation of the darker cock-feathered plumage. Goodale observed, for the first time I think, that the largest wing coverts of the castrated cock become longer. I looked, therefore, with some interest at the condition of these same feathers in the castrated Sebrights. As shown in [plate 10], figures 1, 1a, these feathers are also longer and narrower in the castrated Sebright than in the normal bird.