588 PHYSIOLOGY CHAP. 



opposite side takes 110 part in it. A similar fact was demonstrated 

 by Fload for the motor area of the face (area E of Munk). 



According to Schafer there may be complete paralysis of 

 voluntary movements on the opposite side, with no appreciable 

 loss of sensibility, not merely after removing the cortex of a 

 single motor area, but also when nearly the whole of the motor 

 cortex has been extirpated in the monkey. This was, however, 

 contradicted by the observations of other workers, particularly 

 those published by ourselves in 1885, which were fully confirmed 

 by Mott in 1894. Both our results and those of Mott indicate 

 that a more or less extensive lesion of the Rolandic area is always 

 followed by more or less complete motor paralysis, associated 

 with an appreciable degree of defective sensibility in the limbs. 

 Schafer's criticism of the methods which Mott employed for 

 testing sensibility in the monkey does not appear to us to detract 

 from the value of Mott's interpretation, which for the rest agrees 

 with the exhaustive researches of Goltz. 



At the same time we accept Schiller's conclusions that the 

 motor paralysis present after removal of the cortex of the 

 Rolandic area of the monkey cannot be interpreted, with Munk, 

 as entirely due to loss of sensibility. Logically speaking, the 

 Rolandic area cannot be defined as sensory or motor, but must 

 be regarded as sensory -motor. Motor, because it represents that 

 portion of the cortex which is directly connected by efferent or 

 projection fibres with the lower motor centres of the mid-brain, 

 bulb, and cord, and because impulses for voluntary motor activity 

 and the first phase of this activity originate here ; sensory, 

 because the voluntary acts are guided and controlled by cutaneous 

 and muscular sensations, so that the parts of the cortex in which 

 they originate must be intimately connected with the perceptual 

 centres for these sensations ; sensory -motor, because the dis- 

 turbances incident on the destruction of the Rolandic area are 

 neither exclusively motor nor exclusively sensory. 



Another more specific objection may be raised to Munk's 

 theory. He assumes a constant relation between the lesion or 

 destruction of each sensory region, and the seat and extent of the 

 disturbance of cutaneous and muscular sensibility. Our own 

 researches with Seppilli (1885) both on dogs and monkeys failed 

 to confirm this view, which is obviously opposed by facts derived 

 from objective observation. It is practically impossible to define 

 the limits of the single centres of the excitable area, and to 

 localise the effects of their destruction in one cutaneous region or 

 to one group of muscles. Removal of the cortex from any one of 

 the areas which responds to electrical stimulation by movements 

 confined to a single part of the opposite side of the body produces 

 paralytic effects which predominate in, but are not entirely 

 confined to that part, as they also spread more or less to adjacent 



