FIRST SECTION. 



OF THE STRUCTURE OF FEATHERS AND THEIR PRINCIPAL DIFFERENCES. 



BEFORE I commence the description of the feather-tracts themselves, it appears to me to he 

 necessary to say something of the parts of which feathers are composed, and of the kinds of feathers 

 of which the tracts consist. Indeed, as soon as we begin to examine closely into the law of 

 position of the feathers, we soon find that in certain tracts perfectly definite kinds of feathers 

 occur, whilst in others several sorts are intermixed, and that if we are to distinguish the tracts in 

 accordance with these circumstances we must be acquainted with the different kinds of feathers. 

 But the exact characterisation of these kinds of feathers is impossible without an accurate 

 knowledge of the parts of which feathers consist, and, as even in the description of these I find 

 many material inaccuracies in the writings of authors, I consider it necessary to speak, in the 

 first place, of the parts of feathers. I may, however, remark, .beforehand, that I shall only do 

 this in a general way, and shall not enter into details upon the numerous and often extremely 

 different forms which many of these parts present to the observer. The parts of feathers will 

 only be treated of here so far as is necessary for the comprehension of the laws of their position. 



CHAPTER I. 

 OF THE PARTS OF FEATHERS. 



IN every perfect feather, furnished with all the parts that it can possess, I distinguish : 1. 

 The stem (scapus, Kiel) ; 2. The aftershaft (hyporrhacMs, Afterschaft) ; 3. The barbs (Rami, 

 Aeste) ; 4. The barbules (radii, Strahlen) ; 5. The barbicels (cilia, Wimpern) ; and 6. The 

 booklets (hamuli, Hakchen). These all agree in this respect, that their principal extension is in 

 the direction of their length, so that they form, without exception, elongated structures. 1 



It appears to me that it will not be out of place if I insert here some observations that I have 



