262 3Ir. V. Eorslfiij on the Motor Centres of the Brain, d-c. [March 27, 



The idea of a triangle aud circle having been presented to the 

 intellect by the sensory centres, the voluntary effort to reproduce these 

 is determined upon. Now, if we Ijad a dual mind, and if each 

 hemisphere was capable of acting ^^^r se, then we should have each 

 intellectual area sending a message to its own motor area, with the 

 result that the two figures would be distinct and correct, not fused. 



The other evidence that I referred to above, which is adduced in 

 favour of the synchronously independent action of the two hemispheres, 

 is from the account of such cases ss the following. Professor Ball, of 

 Paris, records the instance of a young man who one morning heard 

 himself addressed by name, and yet he could not see his interlocutor. 

 He re2>lied, however, and a conversation followed, in the course of 

 which his ghostly visitant informed him that his name was M. 

 Gabbage. 



After this occurrence he frequently heard M. Gabbage speaking to 

 him. Unfortunately M. Gabbage was always recommending him to 

 perform very outrageous acts, such as to give an overdose of 

 chlorodyne to a friend's child, and to jump out of a second-floor 

 window. This led to the patient being kept under observation, and 

 it was found that he was suffering from a one-sided hallucination. 



Similar cases have been recorded in w^hich disease of one sensory 

 perceptive area has produced unilateral hallucination. 



I cannot see that these cases in any way supj)ort the notion of the 

 duality of the mind. On the contrary, they go to show tliat while as 

 a rule the sensory percej)tive areas are simultaneously engaged upon 

 one object, it is still possible for one only to be stimulated, and for 

 the mind to conclude that the information it receives in this unusual 

 way must be supernatural, and at any rate proceeding from one side 

 of the body. 



To conclude, I have endeavoured to show that as a rule both 

 cerebral hemisidieres are engaged at once in the receiving and con- 

 sidering one idea. That under no circumstances can two ideas either 

 be considered or acted U2)on attentively at the same moment. That 

 therefore the brain is a single instrument. 



It now appears to me that one is justified in suggesting that our 

 ideas of our being single individuals is due entirely to this single 

 action of the brain. 



Laycock showed that the Ego was the sum of our experience, and 

 every writer since confirms him. But our experience means (1) our 

 perception of ideas transmitted and elaborated by the sensory paths of 

 the brain, and (2) our consciousness of the acts we perform. If now 

 these things are always single, the idea of the Ego surely must also be 

 single. 



[V. H.] 



