Fatio on the Forms and dolours of Plumage. 379 



the rudimentary feather, which, furnished with its envelope, 

 advances obliquely under the epidermis. The constituent 

 pigmented cellules, polygonal, round, and nucleated, arrange 

 themselves in series, composing the barbs, barbules, and axis 

 of the feather." 



" As the cellules which constitute the cortical portion 

 develope and group themselves, their nuclei disappear in part, 

 and they elongate themselves and assume a fibrillose form." 



When the end of the growing feather has become firm 

 enough to pierce its sheath, it puts forth the terminal barbules 

 of the perfect feather, at first rolled round their axis, but soon 

 developing into a tuft by the elasticity they acquire in drying*. 

 iC They are coloured as the extremity of the adult feather should 

 be, and have received already all the pigment which they 

 will obtain." As the growth proceeds, each part receives on 

 emerging from the sheath all the elements of colour which it 

 will afterwards exhibit. At a later period the blood vessels 

 are obliterated, the inferior umbilicus closed, and the sheath 

 thrown off, and the pulp which constitutes the life of the 

 feather dries up. 



In a chapter on u true moults," M. Fatio explains that each 

 bird, whatever its species, receives in its first feathers a certain 

 dose of pigment, and after its first moult the new feathers are 

 supplied with a fresh dose of new pigment, which, being 

 differently elaborated, causes the bird to assume a different 

 livery. M. Patio regards the autumn moult as the true and 

 most complete one, while the spring moult is more or less 

 complete as the existing feathers are capable or incapable of 

 modification. The special decorations which appear on the 

 head and neck at the love season arise from local irritation. 

 When a feather has gone through its course of growth and 

 modification, it gradually dies, and is usually thrust out by 

 a new feather growing at its base. M. Fatio cites on the 

 authority of M. Ltfnel, the case of a goldfinch which had two 

 complete sets of wing feathers, resembling a double set of 

 teeth; the new ones having emerged a little out of their true 

 direction, and not having thrust the others out. 



" We have seen," says M. Fatio, ' c that when a feather has 

 reached its natural size, and has thrown off its external sheath, 

 the internal marrow dries up, and an operculum closes the 

 inferior umbilicus. This drying up and closing are most 

 complete in the longest feathers, but in no case is there any 

 further supply of blood. The researches which I have been able 

 to make on this subject, in many birds, as well as the observa- 

 tions of many authors, like those of M. Martin at the Anas 

 nigra, demonstrate that the skin at the base of a dried feather 

 does not exhibit the local inflammation or sanguine turgescence 



