THE TISSUES 93 



of consciousness, it must be admitted that this metaphysical 

 phenomenon is not an integral part of the response of the 

 nervous system. 



On the other hand, we know that the character of the 

 reaction to any stimulus is largely dependent upon the state 

 of the nervous centres. Just as a touch produces a different 

 effect in a frog poisoned with strychnine, and in one under 

 the influence of bromide of potassium, so a sudden noise may 

 produce a totally different reaction upon a person with a 

 fatigued brain or a brain poisoned by alcohol, and upon one 

 with the brain in a good state of nutrition. 



Not only does the temporary state of nutrition thus 

 modify the result of a stimulus, but the paths of action 

 previously opened and defined through the centres also have 

 a marked influence. These paths may have been formed in 

 past generations and inherited from the parents. In young 

 fowls, as soon as they are hatched, the acts of walking and 

 of pecking are at once performed, and in many families 

 particular gestures or expressions follow certain modes of 

 stimulation in many different individuals without the con- 

 sciousness of the person being involved. They are inherited 

 cerebral reflexes. Paths may also have been developed 

 in the individual as the result of previous activities of the 

 nervous mechanism. For, if a given action has once followed 

 a given stimulus, it always tends to follow it again. This, 

 in fact, is the basis of all rational education to open up 

 paths in the nervous system by which the most suitable 

 response may be made to any given stimulus; and to 

 prevent the formation of paths by which inappropriate 

 reaction may be produced. 



It is very important to recognise clearly the influence 

 of these factors upon the conduct of the individual the 

 nutrition of the brain at any moment, and the inherited and 

 acquired tendencies in particular directions since various 

 abnormalities in moral and social conduct may be explained 

 by reference to them, and since cases of so-called insanity 

 are frequently dependent upon them. 



With the relationship of consciousness to these reactions 

 of the nervous system we shall not deal at present. Con- 

 sciousness is a purely metaphysical conception, and we do not 



