504 



THE NERVOUS SYSTEM. 



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; 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 

 movements may be performed while the mind is, in other 

 things, fully occupied, or in sleep powerless; yet in an 

 emergency, the mind can direct and strengthen them : and 

 it can adapt them to the several acts of speech, effort, etc. 

 Being, for ordinary purposes, independent of the will and 

 consciousness, they are performed perfectly, without expe- 

 rience or education of the mind ; yet they may be employed 

 for other and extraordinary uses when the mind wills, and 

 so far as it acquires power over them. Being commonly 

 independent of the brain, their constant continuance does 

 not produce weariness ; for it is only in the brain that it or 

 any other sensation can be perceived. 



The subjection of the muscles to both the spinal cord 



* 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 intel- 

 lectual process, are termed sensori-motor. 



