260 RAMBLES OP A NATURALIST. 



views, showed how certain results which at first 

 sight seemed to be inexplicable, become easy of 

 comprehension when they are judged by that prin- 

 ciple of the division of labour of which we have else- 

 where spoken.* I have also considered in many 

 memoirs the questions which refer to this order 

 of ideas. Numerous investigations were soon en- 

 tered upon, and pursued in the same direction, 

 both in France and in other countries, and the 

 results which have been arrived at seem daily to 

 confirm more and more the principles, or, to speak 

 more accurately, the tendencies of this school of phy- 

 siological zoology, which at its dawn met with so 

 violent an opposition. We will endeavour to give 

 a general and comprehensive idea of the facts esta- 

 blished by it, and the consequences to which they 

 lead. 



We know that one of the principal differences 

 which separates inorganic bodies from living beings, 

 consists in the necessity for nutrition in the case 

 of the latter. The mineral, when once formed, will, 

 if placed beyond the action of external influences, 

 endure for ever without suffering loss or gain. In 

 the plant and in the animal, an incessant circulation 

 of matter expels from the organism some of the 

 elements which previously had formed a part of it. 

 These elements require to be replaced by others, 

 and to effect this is the end and object of nutrition. 

 Four important functions, which are themselves ac- 

 complished by the aid of several secondary functions, 

 concur in the accomplishment of this fundamental 



* See Chapter II, on the Archipelago of Brehat. 



