INTEODUCTION. 



-•o*- 



" Tlie edifice of tlie world is only sustained by the impulses of hunger 

 and love." — Schiller. 



In that great drama which we call Nature, each animiil 

 plays its especial part, and He who has adjusted and 

 regulated everything in its due order and proportion, 

 watches with as much care over the preservation of the 

 most repulsive insect, as over tjie young brood of the 

 most brilliant bird. Each, as it comes into the world, 

 thoroughly knows its part, and plays it the better 

 because it is more free to obey the dictates of its 

 instinct. There presides over this great drama of life 

 a law as harmonious as that which regulates the move- 

 ments of the heavenly bodies ; and if death carries off 

 from the scene every hour myriads of living creatm-es, 

 each hour life causes new legions to rise up in order 

 to replace them. It is a whiiiwind of being, a chain 

 without end. 



This is now more, fully known ; whatever the animal 

 may be, whether that which occupies the highest or the 

 lowest place in the scale of creation, it consumes water 

 and carbon, and albumen sustains its vital force. 



