1885.] on the Motor Centres of the Brain, &c. 261 



Can this right motor region act in the process of volition, while 

 at the same time this other m(jtor area is also engaged in a different 

 act of volition ? 



Some say this is possible ; but in all cases quoted I have found 

 that subconscious or automatic actions are confused with truly volun- 

 tary acts. I mean that such automatic acts as playing bass and treble 

 are not instances of pure volition, as the attention is not engaged on 

 both notes at once. 



Consider for a moment the passage of the nerve impulses through 

 the brain that would have to occur. At the outset we find that the 

 sensory perceptive centres would have to be engaged with two different 

 ideas at once ; but Lewes showed long ago that introspection tells us 

 this is impossible, that " consciousness is a seriated change of feelings," 

 he might equally well have said ideas. And again, we know that when 

 two streams of energy of like character meet one another, they 

 mutually arrest each other's progress by reason of inteifering with 

 the vibration waves. 



I will show directly that this is actually the case in the action of 

 the cortex when t ;e above-mentioned dilemma is presented to it. 



The experiment I have devised for this purj^ose is extremely 

 simple. 



A person who is more or less ambidextrous, and who has been 

 accustomed for a long time to draw with both hands, attempts to 

 describe on a flat surface a triangle and circle at the same moment. 

 I chose these figures after numerous trials as being the most opposite, 

 seeing that in a triangle there are only three changes of movement, 

 while in a circle the movement is changing direction every moment. 

 To ensure the attempt to draw these figures simultaneously 

 succeeding, it is absolutely necessary that the experimenter should 

 be started by a signal. 



\Vhen the effort is made, there is a very definite sensation in the 

 mind of the conflict that is going on in the cortex of the brain. The 

 idea of the circle alternates with that of the triangle, and he result 

 of this confusion in the intellectual and sensorial portions of the 

 brain is that both motor areas, though remembering as it were the 

 determination of the experimenter to draw distinct figures, produce a 

 like confused effect, namely, a circular triangle and a triangular 

 circle. If the drawing is commenced immediately at the sound of 

 the signal, it will be found that the triangle predominates ; thus if I 

 determine to draw a triangle with my left hand and a circle with my 

 right, the triangle (though with all its angles rounded off) will be 

 fairly drawn, while the circle will be relatively more altered, of 

 course made triangular. On the other hand, if the two figures are not 

 commenced simultaneously, it will be found that usually the one 

 begun last will ajDpear most distinct in the fused result, in fact will 

 very markedly j^redominate. 



Now the course of events in such an experiment appears to be 

 clear. 



