Jan., 1908 



PUBLICATIONS REVIEWED 



55 



tures aud the migration of birds in general. 

 Charles R. Keyes tells of the "Breeding 

 of Harlan's Hawk in Iowa." Mr. Childs 

 recounts some "Long Island Bird Notes for 

 1907." And the same author publishes ex- 

 tracts from an old manuscript consisting of "A 

 Marvelous Collection of Unpublished Bird 

 Songs." The one on the Bobolink, however, 

 has long been a favorite selection for recitation. 

 It was published in the Century Magazine 

 about 1890. The Volume closes with a brief 

 account of "The Childs' Library of North 

 American Ornithology. We judge this to be 

 now the finest private bird library extant. — J. G. 



The Development oe Nestling Feath- 

 ers, by Lynds Jones (=Laboratory Bulletin 

 No. 13, Oberlin College; Oberlin, Ohio; 1907. 

 [November] ;pp. 1-18, pll. I-VIII [=142 figg.]). 



According to Mr. Jones' statement the pur- 

 pose of this paper is to ' give a more complete 

 account of the development of down," and to 

 do away with any conception which may be 

 held at present that the down is a structure 

 distinct from the first definitive feather. While 

 admitting that a continuity between the two 

 has been recognized, he maintains that the 

 down feather is not, as considered by most 

 writers, a relatively separate and distinct 

 feather, but is simply the distal end of the first 

 definitive feather. 



The first part of the paper is given over to a 

 discussion of materials and methods. The 

 author then goes on to trace the histological 

 development of nestling down, which differs to 

 some extent from that of the definitive feather. 

 For example, the epitrichial layer of the skin 

 forms the sheath of the down, but takes no 

 part whatever in the formation of the first de- 

 finitive feather. The development of the 

 barbs and barbules in the down is essentially 

 the same as in the first definite feather, tho as 

 Mr. Jones points out the developing down fun- 

 dament has fewer ridges and a shorter diameter 

 than the developing definite feather fundament, 

 and the down barbules are never provided with 

 hooked barbicels. Further, he finds no chief 

 ridges in the developing down, whereas in the 

 definitive feather they mark the place where the 

 shaft will later be developed. Barbules, how- 

 ever, are found on all down barbs except on 

 certain spike-like feathers from the cuckoo. In 

 the developing down feather the ridges extend 

 from their proximal beginning the full length 

 of the down, while in the definitive feather 

 each ridge extends from its proximal insertion 

 on the developing rhachis only a part of the 

 way to the distal end of the feather germ. This 

 is one of the main distinctions between the 

 down and the definitive feather. 



In the latter part of the article the relation 

 of the down to the first definitive feather is taken 

 up more in detail, and several series of cross- 

 sections are figured to show the manner of 



passing of the so-called down barb-vanes (the 

 barb with its barbules) into the definitive barb- 

 vanes. In most birds the down barb vane 

 passes directly into one or more definitive barb- 

 vanes. Occasionally in the true down of cer- 

 tain altricial birds a "quill" is formed, but the 

 author asserts that this is due more to reduced 

 blood-supply and the drying influence of the 

 air than to any innate tendency to form a true 

 quill, and that it may often be split up if 

 pressed between two hard surfaces. 



Mr. Jones asserts that the first feather to ap- 

 pear in the ducks is made up of the true first 

 down plus the first definitive feather. He thus 

 very cleverly advances this instance as an ex- 

 ample of the primitive relation between the 

 down feather and the first definitive feather. 



Altho the paper presents the facts of the case 

 in a new light, it does not seem to a superficial 

 observer that the proposition that the down is 

 not a relatively separate feather is proved. The 

 growth of the down and the succeeding defin- 

 itive feather has always been considered to be 

 continuous. Dr. Dwight, in speaking of down, 

 says, "It is last seen as waving filaments at the 

 apices of the feathers which succeed it." Mr. 

 Jones in the present paper shows a large series 

 of photographs of first definitive feathers bear- 

 ing down filaments at their tips. Students of 

 feathers have always recognized the fact that 

 the down is borne directly at the end of the 

 first definitive feather, and yet have considered 

 the down a relatively separate feather. The 

 down feather, and all the definitive feathers 

 succeeding it, grow from the same papilla. Re- 

 ferring to the second crop of definitive feathers 

 (the first winter plumage) Ur. Dwight remarks 

 that a feather of the juvenal plumage may oc- 

 casionally be found borne at the end of a feather 

 of this dress! It would appear to be just as true, 

 then, that morphologically the first definitive 

 feather is the distal end of the second defini- 

 tive feather as it is that the down is the distal 

 end of the first definitive feather. The fact 

 that the ecdysis may be discontinuous between 

 the first and second definitive feathers alters 

 the case morphologically not a whit. 



In support of his point that the first feather 

 of ducks represents a combination of the down 

 and first definitive feather of other birds Mr. 

 Jones says that its stages of development and 

 growth cover the period commonly taken by 

 the development of both the down and first 

 feather in other birds. The question of time 

 proves nothing, however. The conception as 

 commonly held that the first feather is the 

 down, and that the second feather is the first 

 definitive, seems to be more in accordance 

 with the facts. The first feather is modified 

 as a covering for the young. In most birds 

 no thick covering is necessary, but in ducks, 

 which need such a covering a down feather 

 with a shaft is developed. Again, why should 

 the structure and development of Anserine first 

 feathers be regarded as indicating the primi- 

 tive structure and mode of differentiation of 

 any typical first feather rather than the struc- 

 ture and development of, say Passerine first 

 feathers? Both have in all probability diverged 

 widely from the primitive common type, and 

 now each is highly specialized to serve its own 



