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 PUBLICATIONS REVIEWED 55 tures dud 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 x9o7." And the same author publishes ex- tracts from an old manuscript eonsistingof "A Marvelous Collection of Unpnblished Bird Smgs." The one on the Bobolink, however,' tins log been a favorite selection for recitation. It was published in the Century Magazine about r89o. The Volume closes with a brief acetrent of "The Chil.ds' Library of North American Ornithology. We judge this to be now the finest private bird library extant.--J. G. TE D]VELOPMINT OF NESTLING 17EATH - ERS, by LYNDS JONES (--Laboratory Bulletin NO. 13, Oberlin .College; Oberlin, Ohio; I9O 7. [Iqovember];pp. I-IS, pll. I-VIII [-I4 2 figg.]). According to Mr. Jones' statement the pur- pose of this paper is to ' give a morecomplete account of the development of down," and to tto away with any conception which may be tmld 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, bnt 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 deanire feather, tho as Nit. Jones points out the developing down fun- dament has fewer ridges and a shorter diameter than the developing definite feather fundament, ad the down barbules are never provided with hooked barbieels. Further, he finds no chief ridges in the developing down, whereas in the dfinitive 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 fromtheix 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 firstdefinitive feather is taken np 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-snpply 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 elefinitive feathers succeeding it, grow from the same papilla. Re- ferring to the second crop of definitive feathers (the first winter plumage) Dr. 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 iust 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 whir. 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 Arisefine 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 Passerinc first feathers? Both have in all probability diverged widely from the primitive common type, and now each is highly specialized to serve its own