EXPLANATION OF OBSERVATIONS 205 



From infancy we are trained to keep all of our volun- 

 tary muscles under a certain measure of control. During 

 the state of concentration just described, this control is 

 relaxed, and our whole musculature becomes the instru- 

 ment for the play of non-voluntary impulses. The 

 stronger the customary control, the stronger must the 

 stimuli be which can overcome it. The steady unremit- 

 ting fixation, which resulted in the horse's selection of 

 the cloths, also involves a high degree of concentration. 



3. Facility of motor discharge. Great concentration 

 was necessary of course, but not sufficient. Persons in 

 whom the flow of nervous energy tended to drain off 

 over the nerves leading to the glands and the vascular 

 system might betray great tension, not so much by move- 

 ments as by a flow of perspiration (we have many excel- 

 lent examples of this given by Manouvrier) '' or by a 

 violent beating of the heart, blushing and the like, — in 

 short, by secretory and vasomotor effects. Or it is not 

 inconceivable that long dealing with very abstract 

 thoughts might have weakened the tendency of overflow 

 to other parts of the brain, and that therefore the entire 

 discharge is used up in those portions of the brain which 

 are the basis of the intellectual processes. But if expres- 

 sive movements occur, the motor pathways must be par- 

 ticularly unresisting in order to take up the overflow of 

 psychophysic energy. This is the necessary condition 

 for obtaining the tapping and the head movements on the 

 part of the horse, although for the tapping there is still 

 one other circumstance necessary: viz., 



4. The power to distribute tension economically — i. e., 

 the ability to sustain it long enough, and to release it at 

 the right moment (after the manner of the curves de- 



