CHAPTER TWELFTH. 



METAMORPHOSES OF ANIMALS. 



366. UNDER the name of metamorphoses are included 

 those changes which the body of an animal undergoes after 

 its birth, and which modify, in various degrees, its organiza- 

 tion, form, and even its mode of life. Such modifications 

 are not peculiar to certain classes, as has been so long sup- 

 posed, but are common to all animals, without exception. 



367. Vegetables also undergo metamorphoses, but with 

 this essential difference, that in vegetables the process con- 

 sists in an addition of new parts to the old ones. A succes- 

 sion of leaves, differing from those which preceded them, 

 comes on each season ; branches and roots are added to 

 the old stem, and woody layers to the trunk. In animals, 

 the whole body is transformed, in such a manner that all the 

 existing parts go to make up a new body. The chrysalis 

 becomes a butterfly ; the frog, after having been herbivorous 

 during its tadpole state, becomes carnivorous, and its stom- 

 ach is accommodated to a new mode of life ; at the same 

 time, instead of breathing by gills, it becomes an air-breath- 

 ing animal ; its tail and the gills disappearing, and legs be- 

 ing formed. 



368. The nature, the duration, and the importance of 

 metamorphoses, and also the epoch at which they take 

 place, are subjected to infinite variations. The most striking 

 changes which naturally present themselves to the mind 



