414 PHYSIOLOGY. 



THTRD CHAPTER. 



THE METAMORPHOSIS.* 



244. 



IN the preceding chapters we have explained how the insect 

 originates, propagates, and subsists, without having noticed the several 

 stages of life it has to pass through, from the first origin of its being 

 until the time it is actively engaged for the preservation of its resem- 

 blance. We have indeed here and there drawn attention to the 

 differences which exist with respect to the mode of taking food and 

 its assimilation with the body between the undeveloped and the perfect 

 insect, but we have not yet explained the several successive periods of 

 development, nor shown their physiological character. This will be 

 the subject of the present chapter. We must now look around us for 

 the causes which determine the form of insects in general. We must 

 endeavour to ascertain why insects take this form and no other, and 

 exhibit a body thus composed of rings and limbs, and what necessary 

 changes a thus formed body must be subjected to, in order to maintain 

 its fundamental figure even through the several developments which 

 every organic, or, at least, animal being, is obliged to pass through. 

 But as an introduction to this investigation, we must prelude with 

 some general observations, which refer to the differences of all animal 

 forms, that we may be in a situation to discover from the differences of 

 these forms, the shape of insects and the object of this shape from their 

 opposition to the rest, and then only, when the cause of the articulated 

 body of insects is discovered, can we proceed with the consideration of 

 the several transformations peculiar to it. 



245. 



The animal kingdom, like all organic matter, the essential character 

 of which is expressed in the idea of becoming or having become, 

 traverses a certain series of grades of development, upon which it 



In this chapter the 245 248 and 251 have been entirely rewritten by the author, 

 and the former 248 and 249 have been changed into the present 249 and 250 TR. 



