PHYSIOLOGY AND NATURAL THEOLOGY 1 23 



mal life, conveying impressions calculated to pro- 

 duce sensations, and sending out volitions to its 

 servants, the organs destined to receive them. 

 The second applies to these organs not necessarily 

 under the influence of the will, such as digestion, 

 circulation, respiration, and secretion. Although 

 each nerve is endowed with its own function, yet 

 all the nerves are so bound together that if one 

 suffers all will suffer in some degree. 



Those nerves which produce impressions on the 

 brain are called sensory nerves, and no sensation 

 can be excited in any part or organ unless conveyed 

 to the brain, the seat of the soul. For example, 

 the sense of touch resides in the ends of the fingers, 

 and the sense of sight in the eye, yet if the nerve 

 which connects these parts with the brain be di- 

 vided, no impression is felt, no sensation excited by 

 the organ. 



The nerves which convey the orders of the soul 

 to the different organs are called motor nerves. 

 If by the act of the will power the soul sends a por- 

 tion of nervous influence to a muscle, it immediately 

 contracts, and those parts to which the muscle is 

 attached will move as directed. If a man or an 

 ape wishes to bend the arm, he will transmit 



