CEREBRUM 191 



by an immediate reaction. The power of suggestion is 

 exaggerated. If a hypnotised person is told that he sees 

 anything he acts at once as if he did actually see it. 



5. Localisation of Functions. The question must next 

 be considered whether special parts of the brain are more 

 especially connected with its three great functions 



A. The reception of stimuli. 



B. The storing of effects, and the associating of present 



stimuli with these stored impressions. 



C. The production of the resulting actions. 



A. Reception of Stimuli. In investigating the existence of 

 special mechanisms for this purpose, several methods of inquiry 

 are available. 



1st. By removing or stimulating parts of the brain in the 

 lower animals and studying the results. 



2nd. By observations during life on the sensations or 

 absence of sensations in patients suffering from disease of 

 the brain, and the determination of the seat of the lesion 

 after death. 



3rd. By the histological study of the different parts of the 

 cortex cerebri. 



ith. By the embryological study of the development of the 

 myeline sheaths of the various bundles of nerve fibres. 



1st. Sensations are the usual accompaniment of the activity 

 of the receiving mechanism. But in the lower animals it is 

 not possible to have a direct expression of whether sensations 

 are experienced or not, and, therefore, in determining whether 

 removal of any part of the brain has taken away the power 

 of receiving impressions, we have to depend on the absence 

 of the usual modes of response to any given stimulus. But 

 the absence of the usual response may mean, not that the 

 receiving mechanism is destroyed, but either that the react- 

 ing mechanism is out of action or that the channels of 

 conduction have been interfered with. (See fig. 98.) 



Thus, if light be flashed in the eye of a monkey, it re- 

 sponds by glancing towards the source of illumination ; and if 

 these movements are absent this may be due (1) to loss of the 



