Animals and the Elements in which they Live. 217 



the larva be after all only the younger state of the pupa, and 

 the pupa the younger state of the perfect Insect. But in the 

 same ratio as we find so frequently throughout the animal 

 kingdom, that the lower condition of structure and develop- 

 ment of a type is manifested in a more bulky body, so we 

 find among Insects, that their earlier state of metamorphosis 

 which is developed under inferior circumstances, reaches its 

 final growth in a more bulky body than that of following 

 periods during which their successive moultings and the 

 transformations of the substance of the body takes place ; 

 the greatest size which the larva acquires is first reduced in 

 its transition into a chrysalis, and this again is reduced in its 

 transition into a perfect Insect, — the development of wings 

 only leaving them seemingly of greater size when their sur- 

 face is extended, though the bulk as a whole be reduced. 

 Weighing these animals in these different states of develop- 

 ment will satisfy the most incredulous of the reality of what 

 is here stated, should the appearance have deceived him 

 before. A silkworm when it begins to spin is much heavier 

 than the chrysalis, and this heavier than the perfect moth. 

 Without directly weighing these animals, we might be satis- 

 fied about this fact if we should consider the amount of silk 

 which is thrown out by the latter, and the amount of fluid 

 which is discharged by the Moth, even before it rids itself of 

 its load of eggs and sperm to enjoy the last moments of its 

 complete maturity. 



If we now allude to the Vertebrata, we shall find very 

 similar facts, and perhaps, in the animals to be mentioned, 

 inducements for the discovery of curious unnoticed connec- 

 tions. And here again we should be cautious, for reasons 

 already alluded to above, not to take the classes as such, but 

 rather to consider their different types separately ; for the 

 cla»s of fishes as a whole cannot be said to contain the largest 

 Vertebrates, nor even to afford any support to the view that 

 aquatic animals in general are larger than terrestrial ; for 

 we find proportionably a much greater number of large spe- 

 cies among Mammalia than among fishes ; we find a greater 

 number of large terrestrial reptiles than of aquatic ones. 



