14 ON THE TRANSFORMATION OF INSECTS. 



throw off, discard, or get rid of all parts of its substance which 

 have become useless. Finally, there is a tendency to form or . 

 create fresh portions of substance, to supply the place and l{ 

 perform the functions of those portions thus thrown off. In 

 this three-fold disposition is to be found a solution of all those 

 mysterious changes we behold in animals and vegetables. 

 Generally this change of substance is most readily detected 

 in the exterior covering ; but in man, the most perfect 

 animal, the only undeniable proof of it is to be found internally I 

 even in the bones. Numberless experiments prove that the 

 substance of bones is continually undergoing change; portions 

 are constantly being absorbed, other portions as continually 

 secreted. By these processes certain portions of matter escape 

 to fulfil other ends, while other portions of matter, introduced 

 as nutriment into the stomach or lungs, are mixed with the 

 blood, and rush to supply the place of that abstracted. Matter 

 cannot perish ; each created article must endure for ever. 

 Neither is matter afresh created. The mass of matter remains 

 unalterably the same ; but to this disposition of matter to 

 change its relative position, thus operating in the substance of 

 organized beings, are to be attributed the shedding of hair in 

 quadrupeds, the moulting of birds, the sloughing of snakes, 

 the extraordinary changes of Amphibia, and the metamorphosis 

 of Insects. 



It has just been observed that the bones of man bear more 

 ample testimony to this constant tendency to exchange of 

 substance, than any of his less solid parts ; the same may 

 perhaps be said of all vertebrates, although some of them testify 

 it so abundantly in other ways. Now the skeleton, or external 

 covering of annulates, performs, in a great degree, the same 

 part in the animal functions as the skeleton of the vertebrates ; 

 the two are not identical but analogous, — they are substitutes 

 for each other. 



In all Condylopodes this tendency to exchange of substance 

 induces a full, complete, and often repeated ecdysis, or change 

 of skin. We find the crab and the butterfly undergoing this 

 ecdysis in an equal degree, both as to extent and number of 

 times, but with how different a result ! — the crab remains a 

 ci*ab, but it is a crawling grub becomes a butterfly ! 



Condylopodes divide into four great groups, three of which 

 are again subdivisible into two each. The easiest and most 



