REFLEX FUNCTION OF THE SPINAL CORD. 505 



spinal cord, do not follow the same irritation when the 

 mind is active and connected with the cord through the 

 brain, is, probably, due to the mind ordinarily perceiving 

 the irritation and instantly controlling the muscles of the 

 irritated and other parts ;. for, even when the cord is per- 

 fect, such in voluntary movements will often follow irritation, 

 if it be applied when the mind is wholly occupied. When, 

 for example, one is anxiously thinking, even slight stimuli 

 will produce involuntary and reflex movements. So, also, 

 during sleep, such reflex movements may be observed when 

 the skin is touched or tickled ; for example, when one touches 

 with the finger the palm of the hand of a sleeping child, 

 the finger is grasped the impression on the skin of the 

 palm producing a reflex movement of the muscles which 

 close the hand. But when the child is awake, no such 

 effect is produced by a similar touch. 



On the whole it may, from these and like facts, be con- 

 cluded that the proper reflex acts, performed under the 

 influence of the reflecting power of the spinal cord, are 

 essentially independent of the brain, and may be performed 

 perfectly when the brain is separated from the cord :* that 

 these include a much larger number of the natural and 

 purposive movements of the lower animals than of the 

 warm-blooded animals and man : and that over nearly all 

 of them the mind may exercise, through the brain, some 

 control j determining, directing, hindering, or modifying 

 them, either by direct action or by its power over associated 

 muscles. 



In this fact, that the reflex movements from the cord 

 may be perfectly performed without the intervention of 

 consciousness or will, yet are amenable to the control of 

 the will, we may see their admirable adaptation to the 

 well-being of the body. Thus, for example, the respiratory 



* Reflex movements, occurring quite independently of sensation, are 

 generally called excito-motor ; those which are guided or accompanied 

 by sensation, but not to the extent of a distinct perception or intellectual 

 process, are termed sensor i-motor. 



