432 THE NERVOUS SYSTEM. 



III. There is at present no doubt as to the existence in the cerebral 

 cortex of a centre of language that is, of a region which, in man, pre- 

 sides over the necessary combinations for articulate speech. Many 

 animals have the power of communicating with each other by cer- 

 tain movements and sounds in such a way as to attract attention, 

 and^enable them to act in concert. The language thus employed is a 

 language of expression, and consists in such modifications of the tone 

 of voice or position of the limbs as indicate pleasure or dislike, excite- 

 ment or alarm, or a friendly or hostile disposition. In man the same 

 methods are largely used to express similar feelings, and to represent 

 others, such as surprise, contempt, amusement, or doubt, which do not 

 seem to exist in animals to an appreciable degree. 



But man has also the faculty of ^^veying definite information by 

 means of articulate speech, in which arbitrary sounds are used to indi- 

 cate special objects, qualities, or acts, as well as the relations between 

 them. The power of using articulate language for the expression of 

 thought is usually in proportion to the development of the general 

 intelligence. In order that it may be exercised, two faculties must 

 come into action, namely, first, the memory, by which the particular 

 words required are brought to the mind ; and, secondly, the voluntary 

 combination of movements necessary for articulation. These acts are 

 performed, in health, with such rapidity that we are not conscious of 

 them ; and articulate speech seems to be a direct sequence of our inter- 

 nal ideas. But pathological cases show that either one or both of the 

 above faculties may be absent, while the ideas and the desire to express 

 them are as distinct as ever. 



This affection is termed aphasia. It does not depend upon a want 

 or confusion of ideas, because the patient is often perfectly clear as 

 to what he wishes to say, although he cannot say it. It is not 

 due to paralysis of the organs of articulation, since the tongue, lips, 

 and palate can be moved for other purposes, in any direction, with the 

 usual facility. It is an inability either to recall the word needed, or 

 to set in motion the nervous actions required to pronounce it. In the 

 former instance it is called "amnesic aphasia." The patient cannot 

 say what he wishes, because he cannot recollect the word he wants. 

 For the same reason he is also incapable of writing it. But if the 

 word which he requires be pronounced for him, he recognizes it, and 

 can repeat it, though in a few seconds it has again escaped him. This 

 disease is an aggravated form of the condition to which many other- 

 wise healthy persons are liable, namely, that of sometimes forgetting 

 a particular word at the moment it is required for use. In some 

 cases of aphasia the loss of power is so complete that the patient 

 can utter only two or three words, which he employs indiscriminately 

 on all occasions. 



In the second variety of the affection the patient knows the word 

 he wants, but cannot articulate it. He can, therefore, express himself 

 perfectly well by writing, but is unable to read aloud even what he has 



