CHAP. XXVII.] CEREBRAL MENTAL SUBSTRATA. 599 



a double or mixed ideal recall occurs, partly having its organic basis 

 in the Kinassthetic and partly in the Visual Centres. 



It seems, therefore, not a little inconsistent to find Ferrier (who 

 rejects the doctrine of Bain and Wundt) writing as follows : " In 

 the same manner as the sensory centres form the organic basis of 

 the memory of sensory impressions, and the seat of their repre- 

 sentation or revival in idea, so the motor centres of the hemi- 

 spheres, besides being the centres of differentiated movements, are 

 also the organic basis of the memory of the corresponding move- 

 ments, and the seat of their re-execution or ideal reproduction.* 

 We have thus a sensory memory and a motor memory, sensory 

 ideas and motor ideas; sensory ideas being revived sensations, 

 motor ideas being revived or ideal movements. Ideal movements 

 form no less an important element in our mental processes than 

 ideally revived sensations." 



There is here an obvious confusion between two totally distinct 

 centres and processes. Ferrier, in fact, by rejecting the doctrine of 

 Bain and Wundt in reference to the ' muscular sense,' or * muscle 

 consciousness,' rejected the natural basis upon which Hughlings 

 Jackson originally founded his hypothesis, as to the existence of 

 ' motor centres ' in the Cerebral Convolutions. Yet on coming to his 

 Chap, xi., "The Hemispheres considered Psychologically," Ferrier 

 writes as though he had forgotten this previous rejection, and the 

 whole discussion to which he had devoted pp. 215-227 of his work. 

 He has, therefore, on the one hand, striven to localize ' motor 

 centres ' in the Cerebral Convolutions, and, on the other hand, he 

 las deliberately rejected that interpretation of the philosophical 

 ind physiological evidence upon which the existence of any such 

 Centres must rest. 



Motor centres, wherever they may be situated, are parts 

 whose activity appears to be wholly free from subjective 

 concomitants. No ' ideal ' reproductions seem ever to take 

 place in such centres ; they are roused into activity by 

 outgoing currents, and, so far as we have any evidence, 

 the induction in them of molecular movements which, 

 immediately afterwards, issue through cranial and spinal 

 Motor Nerves to Muscles are simply physical phenomena. 



* Italics not in the original (loc. cit. p. 266). 



