THE NERVOUS SYSTEM 183 



loss of tactile sense, while Schafer believes that the gyrus for- 

 nicatus is the centre for this sense. It has been objected 

 that in removing this lobe the fibres going to the areas on 

 the outside of the cortex are apt to be injured. According 

 to the observations of Mott, when the cortex round the fissure 

 of Rolando in which the mechanism for causing the various 

 combinations of muscular movements is situated is removed 

 in the monkey, clips may be attached to the skin on the 

 opposite side of the body without attracting attention, 

 while if they are placed on the same side they are at once 

 removed. He therefore regards the Rolandic area of the 

 brain as connected with the reception of tactile impressions. 



As already indicated, this centre must act as a chart of the 

 surface of the body, stimulation of any definite part of the 

 body leading to changes in a definite part of the centre, and 

 these changes are accompanied by sensations referred to the 

 part stimulated. 



We know nothing of the existence of centres connected 

 with the thermal and muscular senses. 



2. Storing and Association Mechanism. The existence of 

 a special part or parts of the brain connected with the storing 

 of impressions, so that they may be associated with present 

 sensations, is indicated by the following considerations : 

 It is this association of present stimuli with past sensations 

 which is the basis of intellectual life, and in man, where 

 apparently the intellectual functions are most highly deve- 

 loped, the frontal lobes of the brain are much larger than in 

 the lower animals. So far stimulation of these frontal lobes 

 has failed to give indication of resulting sensations or to 

 produce muscular movements. They may be extensively 

 injured without loss of sensation and without paralysis, and 

 hence it has been concluded that in them the storing and 

 associating functions must be chiefly located. 



3. Discharging Mechanism. The position of the dis- 

 charging mechanism for cerebral action has been definitely 

 localised, by pathological and experimental observation, in 

 the cerebral convolutions round, or probably chiefly in front of, 

 the fissure of Rolando or sulcus centralis. Destructive lesions 



