518 HISTORY OF PHYSIOLOGY. 



To illustrate this, we need only quote the state- 

 ment which he makes, and the uses to which he 

 applies it. Thus in the Introduction to his great 

 work on Fossil Remains, he says, " Every organ- 

 ized being forms an entire system of its own, all 

 the parts of which fnutually correspond, and concur 

 to produce a certain definite purpose by reciprocal 

 reaction, or by combining to the same end. Hence 

 none of these separate parts can change their forms, 

 without a corresponding change in the other parts 

 of the same animal ; and consequently each of these 

 parts, taken separately, indicates all the other parts 

 to which it has belonged. Thus, if the viscera of 

 an animal are so organized as only to be fitted for 

 the digestion of recent flesh, it is also requisite 

 that the jaws should be so constructed as to fit 

 them for devouring prey; the claws must be con- 

 structed for seizing and tearing it in pieces; the 

 teeth for cutting and dividing its flesh ; the entire 

 system of the limbs or organs of motion for pursu- 

 ing and overtaking it ; and the organs of sense for 

 discovering it at a distance. Nature must also have 

 endowed the brain of the animal with instincts 

 sufficient for concealing itself, and for laying plans 

 to catch its necessary victims * 2 ." By such conside- 

 rations he has been able to reconstruct the whole 

 of many animals of which parts only were given ; 

 a positive result, which shows both the reality and 

 the value of the truth on which he wrought. 



22 Theory of the Earth, p. <)0. 



