CH. IT.] METAMORPHOSES OF INSECTS. 33 



He does not, however, mention whether this was 

 caused by the gradual shortening of all the joints of 

 the legs, or by the want of the terminal ones ; we 

 should presume the latter. 



In order to discover the limbs of the butterfly, 

 Swammerdam and Reaumur had recourse to an un- 

 natural mode of causing the visible development of 

 the various organs. Herold, however, confines 

 himself to nature, and his object is merely to trace 

 the mode of the development and alteration of form 

 which it must be admitted take place at every 

 moulting of the skin ; for instance, the inner skin 

 of a caterpillar just preparing to moult is almost as 

 tough as that of the outer skin of one which has 

 recently moulted, but in the latter nothing is to be 

 found, in a natural state, to represent its future skins 

 or the enclosed chrysalis or butterfly, except mu- 

 cous network or fatty pulp. It is true that, as in 

 the outer skin of the pupa as noticed above, the? ru- 

 diments of these skins may be contained in this net- 

 work, and of the butterfly in this fatty pulp ; but at 

 the same time it must be admitted that the gradual 

 development, or, as Herold misterms it, formation, 

 of this skin, is constantly taking place, and this we 

 imagine is precisely what Herold intends to illus- 

 trate when he states that the successive skins are 

 successively formed, produced, or, as we ought 

 rather to say, developed, from the rete mucosum. 

 In like manner Herold expressly admits that the or- 

 gans of sex of the butterfly are discoverable in the 

 newly-excluded caterpillar, as well as that the fu- 

 ture butterfly is produced from the fatty pulp which 

 is stored up in the larva expressly for its develop- 

 ment, and which constitutes the mucilaginous mat- 

 ter with which a newly-excluded chrysalis is filled. 

 Herold has merely endeavoured to trace the manner 

 in which the limbs of the butterfly are produced from 

 this matter. 



We have omitted to notice the improper use 



