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XVII. On the supposed existence of Metamorphoses in the Crustacea. By J. O. West 

 WOOD, F.L.S. 8s Sec. Ent. Soc. Communicated hy J. G. Children, Esq.^ Sec. R.S. 



Received May 25, — Read June 18, 1835. 



JtERHAPS none of the phenomena of natural history have attracted a greater 

 share of the attention of mankind in all ages than those exhibited by insects in their 

 passage to the perfect state, and to which it is not surprising that the name of me- 

 tamorphoses should have been applied. If this were the case in the darker days of 

 zoological knowledge, when the true nature of these changes was not understood, it 

 is not strange that the subject should have lost none of its interest when, owing to 

 the admirable researches of Redi and Swammerdam, De Geer and Reaumur, all of 

 the marvellous has been removed, and a series of gradual developments exposed, far 

 exceeding in peculiarity those exhibited in any of the other tribes of animals. 



It will not perhaps be considered out of place if we here shortly glance at those 

 general principles which regulate these metamorphoses amongst the ^nnulosa. " Si 

 nous voulons concevoir," observes Latreille, " d'une mani^re claire et positive le 

 sens qu'il faut attacher au mot de metamorphose, il est necessaire que nous nous for- 

 mions une idee exacte de celui de mue ; car leurs significations paraissent avoir 

 beaucoup d'affinite, et il est essentiel de les determiner aussi rigoureusement qu'il est 

 possible*." 



It would, however, lead us to far too great a length were we at the outset to enter 

 into the question of the gradual formation of the various organs of annulose animals 

 from the rete mucosum, as insisted upon by Dr. Heroldt in opposition to the ge- 

 nerally received opinion of Swammerdam, that these various organs are, from the 

 first exclusion of the insect from the ^^^, in a state of existence, but enveloped in 

 various coverings which are successively cast off; although the determination of 

 this question must be considered as having a material influence upon the subject 

 under consideration, more especially as it seems difficult to account for the repro- 

 duction of the limbs of the Crustacea when torn off if we do not adopt the theory of 

 Dr. Heroldt. 



Every animated being in its passage to the perfect development of its species un- 

 dergoes a certain but varied series of changes. In man and most of the vertebrated 

 animals there is a gradual action of the vital forces in different organs till they are 

 fitted for reproduction, accompanied, as progress is made to the adult state, by the 

 acquisition of various appendages, as teeth, horns, pubes, feathers, &c. In addition 



* Cours d'Entomologie, p. 271. 

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