FEATHERS OF BIRDS. 577 



of which constitutes the vane of the feather, are 

 the parts which are first formed ; and their con- 

 struction is effected in the space between the 

 outer capsule (c), and the central bulb (b), in a 

 mode which is exceedingly remarkable, and 

 different from that of the formation of any other 

 organic product with which we are acquainted. 

 Instead of growing from a base, like hairs, and 

 other productions of the integuments, by suc- 

 cessive depositions of layers, the materials which 

 are to compose the laminae are cast in moulds, 

 where they harden and acquire the exact shape 

 of the recipient cavities. The next object of our 

 curiosity, then, is to learn the way in which 

 these moulds are constructed ; and on careful 

 examination they appear to be formed by two 

 striated membranes, the exterior one (e) enve- 

 loping the other (i), or interior membrane. 

 These membranes are separated by a series of 

 partitions, which commence at the edges of the 

 longitudinal white band, seen in Fig. 229, and 

 wind obliquely upwards till they reach the 

 opposite longitudinal band already described, 

 where they join a longitudinal partition which 

 occupies a line answering to that posterior band. 

 Thus they leave between them narrow spaces, 

 which constitute so many compartments for the 

 deposition, as in a mould, of the material of 

 each lamina. The course of these channels, 

 and their junction at the back of the matrix is 



VOL. I, p p 



