ADAPTATION OF PARTS. 233 



that best size and best form. If her creatures wanted but to 

 see, a globular eye floating in space might perhaps be the 

 uniform character of the animal world ; if to see and to eat, 

 an eye and a mouth would be given ; if to move swiftly in the 

 air were desirable, wings must be supplied ; if on earth, legs 

 must be added ; if in the water, fins. To carry all these or- 

 gans, and to contain muscle to guide and govern them, a 

 body must be added. Each part of the body will be of the 

 best size and best form for the functions it has to perform. 

 We have seen that insects in their larva state have a very uni- 

 form allowance of muscle to each segment. In the imago, 

 the charge of supporting the whole body in the air is entrust- 

 ed sometimes to a single segment ; and, in order to supply 

 sufficient strength for the purpose, nature robs the neighbour- 

 ing segments of their muscle, and gives it the one which 

 needs it. In the head, the mouth-feelers and ei/es operate in 

 the same manner one on another. Observe the dragon-fly, 

 the emperor of his tribe ; his wings rustle as he hovers sta- 

 tionary and hawk-like in the air ; his appetite is insatiable ; 

 his food the active occupants of his own element ; it is given 

 to him in charge to set bounds to the increase of the insect 

 race ; he beholds his prey afar off*; he darts on it like the ra- 

 pidity of a lightning flash ; to devour it ere life is departed is 

 the work of an instant ; he sails round and round ; he soars 

 up and down ; when the sky is serene, he seeks his prey, like 

 the swallows, almost beyond the reach of human sight. What 

 organs does such an animal require? Are they not these, — 

 eyes, mouth, and wings ? How has nature provided for his 

 wants ? Regard his head — below, it is all mouth ; above, it 

 is one continuous eye. Contemplate his wings — their cha- 

 racter is strength and lightness — power and activity. His body 

 is slender and graceful ; hke a rudder, it serves as an instru- 

 ment wherewith to shape his course. Porrected feelers, whe- 

 ther cranial^ lateral, or maxillary, would be comparatively use- 



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