84 



GENERAL OBNITHOLOGT. 



stem. 



Structure of Feathers. — A perfect feather, possessing all the parts it can have devel- 

 oped, consists of a main stem, shaft or scape (Lat. seapus, a stalk ; fig. 19, ad), and a supple- 

 mentary stem or after-shaft (hyporhachis : Gr. viro, hupo, under, pd^if, rhachis, a spine or ridge; 

 fig. 19, 6), each bearing two webs or vanes (Lat. vexillum, pi. vexilla, a banner ; fig. 19, c, c, c), 

 one on either side. The whole scape is divided into two parts : one, nearest the body of the 

 bird, the tube or barrel or "quill" proper (Lat. calamus, a reed), which is a hard, horny, 

 hollow, and semi-transparent cylinder, containing a little pith in the interior ; it bears no webs. 

 One end of this quiU tapers to be inserted into the skin ; the other passes, at a point marked by 

 a little pit (Lat. umbilicus, the navel) into the shaft proper or rhachis, the second part of the 

 "*"•" The rhachii is a four-sided prism, squarish in transverse section, and tapers gradually 



to a fine point ; it is less 



horny than the barrel, very 



elastic, opaque, and solidly 



pithy; it bears the vexilla. 



The after-shaft, when well 



developed, is like a duplicate 



in miniature of the main 



feather, from the 



which 



stem of 



it springs, at juno- 



if calamus with rha- 



lose by the umbilicus. 



generally very small 



with the main 



.^ feather, though 



'» . , '. Twin a few kinds 

 of birds ; it isi . 



Xirely want- 

 ing m some gro»ir^ ^.^^^ _ 



it is never developed ' 

 Q the 

 large, strong wing- antv 



feathers. The vane con^ „ . . 



1 , i;^oo^ riAoi a series of appressed, 

 flat, narrowly linear oi> ff ' 



i vi;„„oi^ nv, t>ia^ce-linear laminae or 

 plates, set obliquely on tne \ 



diverging out from it at a varf his by their bases, 

 ing in a free point: each such? "Pe^ angle, end- 

 is caHed a barb (Lat. larba, a b.".ow, acute plate 

 Now if these laminae or barbs siP J «g- 20, a, a). 



tne nga. .».= each other, like the leaves of a ly lay alongside ' 



• . ... t>,Pvpfore thev are connected together; for, jpk, the feather 

 would have no ^^-^^^^^^ ' ^^J^/^^tl its vanes of the seco- as the rhachis 



bears its vane or series of barbs, so does «acli baro baorder.'or little 



.anes, called «. ^^^^^^ ,;^^^^^^^^ of th. exactly what 



the barbs are to the shaft, and are similarly give ^^^^^^ ^^ 



the barbs ; they make the vane truly a -^Mhat^^^^J are variously shapedPgether that 

 some Uttle force is required to pull ^"^^^ '^P^f ^^f/;'" J^ , ring to a slend^t generally 

 fiat sideways, with uppe-^ lo- ^o^ ^^^^^^ ;;Xt?e next b'arb, crossinghready end, 



'"?'f ^iT TheL are st^y a^ort^^ ^ , ,„ ,,e barbules, just- be J;., a W. 

 f1^b'jbSiwelt;:d out, rnLnly differ from each other in that bu.i;:^in^^^^ 



Pig. 20. — Two barbB, 

 a, a, of a vane, bearing an- 

 terior, b, b, and posterior, 

 cliarbule^ enlarged ; after 

 Nitzsoh. 



Fig 19. — A partly pennaceons, partly plum- 

 ulaoeous featlier, from Argus pheasant; after 

 Kitzsch. a<?,main8temi<J, calamus; a.rba^Us 

 fee vanes cut away on left side in order not 

 to taterfere with 6, the after-shaft, the whole of 

 the right vane of which is likewise cut away. 



