ON THE FUNCTIONS OF THE CEREBRUM 341 



one variety of sensorial impression. On the other hand, the more 

 or less complex cerebral processes which are needed for the evolu- 

 tion of the percept symbolised by a certain word may involve the 

 cortex in and near each of the several projection spheres. For 

 example, the word " mouse " at once sets on foot processes of 

 association which pass to every projection sphere with the solitary 

 exception of the gustatory, and even this may be reached in a 

 person who has eaten a fried mouse in the hope of thereby re- 

 covering from an attack of whooping cough. 



We may note a word, i.e. receive the sensorial impression 

 produced by it ; we may go a step further and recognise it as 

 understandable ; but it is only when, by active, though not 

 necessarily voluntary, processes of cerebral association, numerous 

 sensori-memorial images of different orders have thereby been 

 aroused into the field of consciousness, that the word acquires 

 meaning. These processes of association are of widespread dis- 

 tribution, and differ in detail, though they are similar in their 

 general tendency, on each occasion on which they occur. In the 

 normal brain these processes of association are directed and con- 

 trolled, and suitable sensori-memorial neurone complexes are ac- 

 cepted, whilst undesirable are rejected, by means of the centre of 

 higher association. In dreamy states they follow certain natural 

 laws, and their course depends solely on the existing state, as 

 regards excitability, of the various associated groups of neurones. 

 In the maimed brain of an aphasic, whether it be functioning 

 in a controlled or in an involuntary manner, such processes 

 of association are necessarily imperfectly and inadequately 

 performed. 



The fairly common, rather than very occasional, determination 

 of an " area of Wernicke," and therefore of " aphasia " as a special 

 symptomatology, like the determination of other special symp- 

 tomatologies through local ceiebral lesions, depends, in fact, on 

 the distribution, and consequent liability to occlusion, of certain 

 branches of the cerebral arteries. Had the arterial supply of the 

 cerebrum been evolved in a different manner, it is conceivable 

 that " aphasia," as it occurs, would be unknown, for lesions due, 

 e.g. to tumours, traumatism, &c., would not have sufficed for its 

 complete identification and description. 



" Aphasia," however, exists, as a complex of varying types of 

 symptomatology ; and the study of these by Marie has produced 



