574 THE MECHANICAL FUNCTIONS. 



of the several parts of the feather being succes- 

 sively deposited and fashioned into their proper 

 shapes in different places : for while the first 

 laminae are constructing in one portion of the 

 cylinder, the next are only just beginning to be 

 formed in another ; and while the outer covering 

 of the stem is growing from one membrane, the 

 interior spongy tissue is deposited in other places, 

 in various stages of softness or consolidation : so 

 that the whole composes a system of operations, 

 which may be said to resemble in its complication 

 at least, although on a microscopic scale, an ex- 

 tensive manufactory. Hence will be readily 

 understood how great must be the difficulty of 

 tracing all the steps of these multifarious pvo- 

 cesses, which are carried on in so small a space : 

 and this difficulty is much increased from the 

 circumstance that the organ in which they take 

 place is itself only developed as the work pro- 

 ceeds, its different parts being produced succes- 

 sively in proportion as they are wanted, and their 

 form and structure undergoing frequent variation 

 in the course of their developement. 



The most elaborate, and apparently accurate 

 researches on this intricate subject, are those 

 lately undertaken by M. Frederick Cuvier, from 

 whose memoir* I have selected the following 

 abridged statement of the principal results of his 



* Memoires du Museum, xiii. 327 ; and Annales des Sciences 

 Naturelles, ix. 113. 



