84 THEORY OF THE EARTH. 



tually corrrespond, and concur in producing the 

 same definitive action, by a reciprocal reaction. 

 "None of these parts can change in form, without 

 the others also changing ; and consequently, each 

 of them, taken separately, indicates and ascer- 

 tains all the others. 



Thus, if the intestines of an animal are so or- 

 ganised as to be fitted for the digestion of flesh 

 only, and that flesh recent, it is necessary that its 

 jaws be so constructed as to fit them for devouring 

 live prey ; its claws for seizing and tearing it ; its 

 teeth for cutting and dividing it ; the whole sys- 

 tem of its organs of motion, for pursuing and 

 overtaking it ; and its organs of sense for discover- 

 ing it at a distance. It is even requisite that na- 

 ture have placed in its brain the instinct neces- 

 sary for teaching it to conceal itself, and to lay 

 snares for its victims. 



Such are the general conditions which nature 

 imposes upon the structure of carnivorous ani- 

 mals ; and which every animal of this description 

 must indispensably combine in its constitution, 

 for without them its race could not subsist. But 

 subordinate to these general conditions, there ex- 

 ist others, having relation to the size, the species, 

 and the haunts of the prey for which the animal 

 is adapted ; and from each of these particular con- 

 ditions, there result modifications of detail in the 

 forms which arise from the general conditions. 



