On the Origin of Feathers. 



By Hans Gadow, F. R. S., Cambridge. 



In the „Dictionary of Birds'V) article „Feathers" I stated 

 that : The Teleoptiles [the feathers of adult birds] whether 

 contour feathers, or downs, are each origmally preceded by a 

 Neossoptile [first, or nestling plumes], the base of which is 

 in direct continuity with the tips of the rami of its succeeding 

 final f eather ; but owing to a shortened process of development or 

 caenogenetic oonditions many, or even all Neossoptiles may 

 occasionally be suppressed, to that the tips of the first feathers 

 which appear, are actually those of the second generation." 



When, in the autumn of 1908 I had the pleasure of delivering 

 a course of lectures ,,on the coloration of Birds" at the Lowell 

 Institute, Boston, Mass., I was not aware of Dr. Lynd Jones^) 

 paper on the development of nestling feathers, nor of Oscar 

 Riddle's^) papers, because I had just returned from a six months 

 tour through Mexico. At Boston I elaborated the above Condensed 

 Statement and explained that the now well known structural 

 continuity of the neossoptile with the teleoptile was all-important 

 for our understanding of the moult or succession of feathers, and 

 of their phylogeny itself. Often, most completely in Ducks and 

 their allies, the Neossoptile of first down forms a complete, typical 

 spool which in time is lifted out of the skin, whilst it may still be 

 enclored by remnants of its sheath ; then the base of the spool splits 

 and its constituent shreds reveal themselves as the direct con- 

 tinutions of the tips of the rami or barbs of the next following 

 feather or first teleoptile. In such a case therefore the first and 

 second generation are still continuous in structure and in time, 

 although the transition is sharply marked by the formation of 

 a spool. This process finds a fair analogy in the ,,year-rings" of 

 the horns of cattle. 



The moult of feathers is therefore the periodical Interruption 

 of an originally ever-growing feather. The Interruption in structure 

 and in time between any two successive teleoptiles has become 



^) A. Dictionary of Birds. Alfred Newton assisted by Hans Gadow, 

 London 18;)3— 18 G. 



2) Laboratory Bulletin No. 13, Oberlin College; Oberlin, Ohio 1907. 



^) The cause of the production of Down and other Downlike struc- 

 tures in the plumages of birds. Biological Bulletin, vol. XIV, Februar 1908. 



The Genesis of fault-bars in feathers and the cause of alternation of 

 light and dark fundamental bars. Biol. Bulletin, May 1908. 



