THE FUNCTIONS OF LIFE. 37 



has conferred these gifts has conjoined that of 

 voluntary motion, by which the animal may 

 not only obtain possession of such objects as 

 minister to its gratification, and reject those 

 which are useless or hurtful, but may also move 

 from place to place, and enlarge the sphere ot 

 its perceptions and of its power. The same 

 mass of nervous substance which, under the 

 name of brain, we have recognised as the organ 

 of sensation, is also, as will afterwards be shown, 

 the organ of volition ; and the medium, by 

 which the commands of the will are transmitted 

 from the brain to the mechanical apparatus em- 

 ployed for motion, is again certain filaments of 

 nerves ; but these nervous filaments are distinct 

 from those which are subservient to sensation. 



Next in importance, then, to the organs of 

 sensation and perception, are those of Voluntary 

 Motion. They comprise two kinds of objects; 

 first, the establishment of a certain mechanism, 

 having the cohesion, the strength, and the mo- 

 bility requisite for the different actions which the 

 animal is to perform ; and, secondly, the pro- 

 vision of a power, or agent, which shall be capable 

 of supplying the mechanical force for setting this 

 machinery in motion. With these objects must 

 be combined various subsidiary arrangements 

 relating to the connexions, the support, the pro- 

 tection, and other mechanical conditions of the 

 organs of the body. It will be convenient to 



