Hans Gadow: On the Origin of Feathers. 211 



complete, and therefore these feathers represent typical, individual 

 generations. 



The connexion with the Neossoptile is therefore a tnily palin- 

 genetic feature. In many birds this first feather degenerates, 

 sometimes with a mere vestige of a shaft, or the whole is rednced 

 to a few filaments attached to the rami of the first teleoptile, or 

 it may be suppressed altogether. 



Unfortunately Dr. Jones, after quoting my passage cited 

 above, did not rise to the broader view. He says „Though a 

 continuity between the nestling down „neossoptile" and the 

 definitive feather „teleoptile" has been recognised, the former 

 has been regarded as a relatively complete and distinct feather. 

 I shall attempt to show that the neossoptile is only a more or less 

 differentiated part of the first teleoptile." In the summary of 

 his paper, which is füll of interesting detail and is amply illustrated, 

 he states the following conclusions. 



3. „The first down has no shaft. The barbvanes [rami] which 

 compose the first down, aro continuous and separate through 

 the entire length of the down." So they are in many birds, but 

 in many others the nestling downs have a shaft, for instance 

 Rhea, Dromaeus, Casuarius, Anserif ormes ; cf. Gadow, Bronn's 

 Thier-Reich, p. n34 



4. ,,The first down has no quill." In order to be able to 

 make such a statement he describes the quill or spool, where such 

 occurs, as ,,a more or less homogeneous horny cylinder which can 

 be split along the lines continuous with the barb-vanes by pressing 

 or rubbing the so-called ,, quill" between two hard surfaces"! We 

 may wonder what would be his definition of a quill or feather- 

 spool. Distally it passes imperceptibly into the shaft with its vanes, 

 and proximally it comes to on apparenty sudden termination only 

 in the teleoptiles. The interesting fact is that in some neossoptiles 

 this spool is still in an incipient, archaic, condition. 



5. ,,No shaft is formed at the extreme distal end of the first 

 definitive feather. The rudiments of a shaft begin to appear 

 several millimeters proximal to the distal end of the feather by 

 the coalescing of two or more barb-vane ridges." One falls to 

 see the importance of this statement. Did he expect the shaft 

 alone to pass upwards into the spool of the neossoptile ? How 

 could this happen if, as he asserts, the first down has neither 

 shaft nor quill ? Moreover there are many teleoptile downs which 

 have no shaft. If any thing, his remark could be taken to mean 

 that there is a difference between the neossoptile and the first 

 teleoptile, a conclusion which he rejects. 



7. ,,The first down and its succeeding definitive feather are 

 produced by one continuous growth, and therefore cannot be 

 regarded as two distinct feathers. The first down is the plumu- 

 laceous tip of the first definitive feather." 



14* T.Heft 



