142 ORTHOGENETIC EVOLUTION IN PIGEONS. 



at the tips of all these feathers, and it seems to be of the same nature as the flutes 

 of the primaries i.e., due to unequal development of the web. It is the lower 

 web and the tip of the feather in all except the primaries, in which it is the upper 

 web that is modified. These feathers show plainly that the fluted condition passes 

 by degrees into the frilled condition. 



THE ASSOCIATION OF FRILLS WITH OTHER EVIDENCES OF WEAKNESS.' 



Photographic illustrations have been prepared to assist an understanding of the 

 conditions presented by the following cases: 



(1) An adult female homer (E) which was hatched "late in the season" (Novem- 

 ber 15, 1908) has a number of small frills on the wing-coverts (pi. 71, figs. B, C) and 

 has fluted primaries. This bird came from a mating in which the wing-bars were 



1 The author seems to have made but little special study of the inheritance of the small or relatively rudimentary 

 "frills" which are discussed in this chapter, though the references to the homers which are referred to at this point 

 have a bearing on the subject. The reason for his scant attention to the behavior of the character in heredity is easily 

 found in his point of view, which, in short, was that the basis for production of frills exists in most or all pigeons 

 perhaps in most birds and that "weakness," perhaps particularly the weakness associated with domestication 

 and inactivity, seems to magnify the exhibition of the character. It therefore seemed necessary to examine the points 

 of weakness in the frilled individual in order satisfactorily to account for its presence. The question of the heredity 

 of these early stages of the character a thing probably not easily proved in view of the important role of strength 

 and weakness possibly seemed of less importance, because higher grades of "frill" have been attained in pigeons, 

 fowls, canaries, etc., and are there well known to be transmitted from parent to offspring. Inbreeding is one such 

 cause of weakness, and white color is one evidence of it. The several conditions which make for weakness in the off- 

 spring of pigeons are fully treated in Volume II. -Eo. 



EXPLANATION OF PLATE 70. 



A. Adult male common pigeon (mondain) from dealer, x 0.8. Hayashi del., Jan. 1900. 



Flutes or folds in several primaries (see below) in lower webs of tertials and secondaries; these are terminal in 

 three long coverts giving rise to rudimentary frills. Flutes thus pass into frills. 



Color almost black, with pale-gray chequers like those of the guinea-pigeon. Fluting strongest on the longer 

 (left side) primaries, as follows: 



First shows only faint trace of them in distal 25 mm. 



Second shows decided folds for terminal 37 mm. 



Third shows about same number, but slightly stronger. 



Fourth shows about 7 folds in 31 mm., about equally strong. 



Fifth shows about 6 folds in 25 mm., still more shallow. 



Sixth shows about 5 folds in 25 mm., still more shallow. 



Seventh shows about 5 folds in 25 mm., but folds a little less marked and smoothed out before reaching 

 the mid-rib. 



Eighth shows about 4 open shallow folds near tip. 



Ninth shows only faint traces. 



Tenth shows only faint traces. 



Primaries 9 and 10, dark ; all others white. 



B. Adult male guinea-pigeon, Columba guinea, x 0.8. Hayashi del., Jan. 1900. 



The color shown is hardly that of the bird, but the triangular spots are practically the same. Coverts less in 

 number than in the domestic pigeon. The long coverts have the shape and arrangement characteristic of wild pigeons. 

 I lulrs or folds seen in primaries. In a second specimen I could scarcely see any trace of these folds. They are here 

 less developed than in the guinea-marked common pigeon shown above. The flutes are present in the primaries, 

 without any sign of modification of any of the anterior feathers of the wing. 



EXPLANATION OF PLATE 71. 



A. Adult male common pigeon, red with white primaries and smaller guinea-marks. From a dealer 



in 1906; in 1909 noted frills on the wings; primaries fluted. 



B. Adult female homer (E) hatched Nov. 15, 1908; photographed Sept. 1909. 



From a mating in which bars were being narrowed in the young. She had a half-sister (nearly white) and a half- 

 brother with wing frills. ;md still another half-brother (H 1) with a breast frill. 



C. Adult female homer (E) same as above. Four small but plain frills seen from behind wing 



(held in hand). 



