332 Observations cni the Structure of Feathers and Hair. 



these organs, to which he was led by new observations, different 

 from any previously made on the subject. 



The differences which the author establishes in his first me- 

 moir between hairs and feathers, were founded on the circum- 

 stance, that hairs are produced by the exhalation of the matter 

 which is secreted by the nervous papillae, which serve successively 

 as a mould to each of their parts, while the formation of feathers 

 was more complicated, according to his ideas, and the presence of 

 a particular organ rendered necessary, which he named the Pro- 

 ducing Capsule (Capsule productrice.) This capsule is the result 

 of a spontaneous and transitory creation, analogous to that which 

 gives rise to the horns of the stag, of whose future forms, or 

 even existence, no indication is presented previous to their ap- 

 pearance. The producing capsule of the feathers is formed ab- 

 solutely in the same manner on the dermic papilla, which in- 

 deed furnishes it with a base, and contributes to its development 

 by the enlargement of its proper vessels ; but, without the cap- 

 sule having more connection with the papilla than any parts of 

 organized bodies have which assumed their points of departure 

 from those which have preceded them. A circumstance which 

 has undoubtedly prevented naturalists hitherto from being ac- 

 quainted with the producing organ of the feathers, is, that it 

 continually varies, and that only a small portion of it can be ob- 

 served at once. The part which has secreted the first portion 

 of a feather is obliterated, in fact, the moment this portion is 

 formed, and the part which is to follow makes its appearance. 

 This, again, which will produce the second portion, is obliterat- 

 ed in its turn, as soon as it has answered its purpose ; and this 

 process continues until the feather is completed. It is therefore 

 seen, that the producing capsule, could the parts of which it is 

 successively formed be united, would necessarily equal the fea- 

 ther itself in length. If we now reflect that there are birds in 

 which the feathers are renewed every year, in a few days as it 

 were, and that, of these feathers, there are some which have a 

 length of several feet, an idea will be formed of the importance 

 which at this period the twofold formation of the capsule and 

 feather acquires ; and hence the most satisfactory explanation 

 of the accidents which in birds accompany the casting and de- 

 velopment of the feathers at the period of moulting. 



