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Direction of oui thoughts in one sense, would be impossible. 



It is the question if, in this exertion of the attention which ap- 

 pears so undoubtedly active to the self observation, the remembrance 

 of movements do not play a similar part, as was the case with 

 the will to move. 



Can the subject actively, by the association of psychomotor cell- 

 groups with the modifications which are accompanied by conscious 

 remembrances in the observing regions of the cortex, be made to 

 fancy, that he fixes his remembrance? 



To answer this question, it is necessary to know beforehand, 

 whether there are contractions of the muscles, and if so what con- 

 tractions, through which the man who fixes his attention is diffe- 

 rent from himself, as he is when he is not attentive. 



For every modification of the psychomotor area must necessarily 

 flow to the periferie muscles. Even if it is not very strong, it must 

 bring about some modification in the corresponding group of muscles, 

 though it be only a beginning of contraction, an increase of the 

 tension of the muscles. 



It will appear — and this I want to show in my exposition --- 

 that the attentive man distinguishes himself from one not attentive 

 in various respects by changes of a motor nature and that this 

 remarkable combination of movements may be reproduced from one 

 single point by electric stimulation of the cortex of the brain of 

 a dog. 



§ II. The variations in the volume of the brain during 

 ■psychical processes. 



Before entering upon my real subject, I must dwell for a moment 

 on the modifications, which occur in the brain when at rest or 

 during conscious function. Many years ago Mosso has proved that 

 the volume of the brain varies continually. Sometimes people have 

 a defect in the bones of the cranium. Then the brain, covered 

 only by the membranes on that place, is fit for observation. If the 

 movements of the brain in half-sleep are registered — movements 

 visible even to the naked eye — it appears that the brain regu- 

 larly varies in volume according to the varying quantity of blood 

 it contains. We see then : 



1". Oscillations caused by pulsation, because every contraction 

 of the heart urges blood in the scull. 



2°. Oscillations caused by respiration, because at every expira- 

 tion the blood can flow less easily from the brain. 



