COINAGES OF THE BRAIN. 291 



tions of pendulums, and the tremblings of the particles of sounding 

 bodies." And of what takes place in the brain when the impression 

 from the outer world is converted into that proceeding from brain to 

 body and to the outer world again, we are likewise in the depths of 

 ignorance. But despite our inability to read between the lines of 

 the brain-work, the general nature of nerve-action remains as a clear 

 and patent basis for further research. Nervous acts are now spoken 

 of in physiology as being founded on the grand principle of " reflex 

 action/' with the name of which every schoolboy is familiarised by 

 his physiology-primer. The ordinary acts of living and being are 

 regulated on this duplex system. An impression (which we call 

 afferent or sensory) travels in \vard to the brain or other centre, and is 

 there converted into another impulse (named efferent or motor), which 

 passes outwards to muscles, to glands, to other organs, or it may be 

 to some other part of the brain itself. The original impression or 

 sensation is thus "reflected," as it were, from a nerve-centre to some 

 other organ or part. The sensation of withdrawal from danger, to 

 which the threatened blow gives rise in the brain, was duly "reflected," 

 and thus passed onwards to the head and neck-muscles, and, in the 

 case of practical retaliation, to the muscles of the limbs. So that, in 

 this view of matters, the brain may be regarded as largely performing 

 the functions of a complex " clearing-house," where the varied busi- 

 ness-concerns of the frame are assorted, parcelled out, rearranged, and 

 finally transmitted to their proper destinations. 



Other examples of this duplex system, and of the power of the 

 head-centre of the nervous system to receive and retransfer impres- 

 sions and sensations, may throw a further light upon some special 

 features and noteworthy characteristics of its action. Select, for 

 instance, the sensation of touch, and we shall have forcibly impressed 

 upon our understanding the fact that the brain or sensorium is the 

 true and actual seat of knowledge. This latter truism, plain as it 

 may appear, is not usually appreciated until the attention has been 

 directly called thereto. It is needful, in truth, for the correct under- 

 standing of the evolution of mind-phantasies and illusions, that such 

 a truth should be continually present in all its plainness to the mind. 

 We touch a table, and the rationale of the nervous acts therein 

 implied is readily explained. Thought laying aside the question of 

 antecedent conditions and influences begins the act, and deter- 

 mines the desire to touch the object. This thought next becomes 

 transformed into nerve-force how, why, when, where, are details 

 all-important in their profundity, but immaterial to the plain issue 

 before us. This nerve-force passes, under the direction of the brain, 

 along definite nerve-tracts, leading, say, to the forefinger of the right 

 hand. On the way, it stimulates the appropriate muscles. Thus the 

 finger is brought in contact with that part of the outer world repre- 



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