THEORY OF THE EARTH. 87 



ear, the connection of which with the perfection 

 of the senses of smell, sight, and hearing, is evi- 

 dent. In a word, the form of the tooth regulates 

 the forms of the condyle, of the scapula, and of 

 the claws, in the same manner as the equation of 

 a curve regulates all its properties ; and as, by ta- 

 king each property separately for the base of a 

 particular equation, we find both the ordinary 

 equation, and all the other properties whatever ; 

 so, the claw, the scapula, the condyle, the femur, 

 and all the other bones taken separately, give the 

 tooth, or are reciprocally given by it ; and thus, 

 by commencing with any one of these bones, a 

 person who possesses an accurate knowledge of the 

 laws of organic economy, may reconstruct the 

 whole animal.. 



This principle seems sufficiently evident, in 

 the general acceptation in which it is here taken, 

 and does not require any fuller demonstration ; but 

 when it comes to be applied, there will be found 

 many cases where our theoretical knowledge of 

 the relations of forms will not be sufficient, unless 

 it be supported by observation and experience. 



For example, we are well aware, that hoofed 

 animals must all be herbivorous, since they have 

 no means of seizing prey. It is also evident, that, 

 having no other use to make of their fore-legs than 

 to support their body, they do not require a shoul- 

 der so vigorously organised as that of carnivo- 



