LANGUAGE FACULTIES 661 



extirpation of the cortical region corresponding to the extremities, This 

 mechanism, however, does not suffice for complicated movements, and still 

 less for learning new movements. In such cases several other portions of the 

 cortex must be called into play and it is these which finally stimulate the 

 discharging cells of the motor pathways. 



This conclusion is supported by the circumstance that in localized artificial 

 stimulation within the motor cortex (provided no epileptic attack is induced) 

 the movements obtained are always relatively simple, being confined to a few 

 groups of muscles. They almost always lack the orderly coordination of 

 several different groups which characterize the voluntary movements, and even 

 appear in certain reflexes from the spinal cord (see page 587). 



The following observation may be cited as still further support for this 

 conception. If the cortical area of a definite part of the body be sought out 

 by electrical stimulation, and it be then isolated from the rest of the cortex by 

 a circular cut, the effect is just the same as if it were extirpated in toto, 

 although the blood supply may not have been disturbed by the process of cutting 

 (Marique, Exner, and Paneth). 



The following experiment by J. R. Ewald likewise speaks against the idea 

 that the voluntary motor impulses originate in the motor cortical areas. A 

 small hole is made in the skull of a dog and after opening the dura mater, elec- 

 trodes are fastened in in such a way that the cortex can be stimulated as the 

 animal moves freely about. Different movements can then be induced accord- 

 ing as one or the other of the cortical fields is stimulated; but the animal takes 

 no notice of them, even when just in the act of making a voluntary movement. 

 It is clear that such a stimulus does not interfere with the normal stimulus, 

 which, it would seem, therefore, must originate elsewhere. 



2. LANGUAGE FACULTIES 



The ability to use language, as even a cursory survey of the way in which 

 we acquire the power of speech will show, requires the cooperation of a number 

 of different parts of the cerebral cortex. Lesions in different parts of the 

 cortex and of the corona radiata produce various disorders in the language 

 powers, the study of which will give us further insight into the mechanism 

 concerned in psychophysical processes. What follows is based mainly on the 

 ideas of v. Monakow. 



A child is born with the ability to move all his muscles ; he sees and hears. 

 But he lacks for the most part the power to coordinate his movements to any 

 purpose: he does not understand what he sees, he does not comprehend what he 

 hears ; he has " no language but a cry." But his power to see and to hear begins 

 to be exercised. He gradually learns to recognize people and the commonest 

 objects about him, he hears the names by which these people and things are 

 called and learns little by little to recognize them. Finally, he begins to imi- 

 tate these sounds and after many fruitless attempts succeeds at last in com- 

 passing the first intelligible and orderly articulate sound. This is usually the 

 name of his mother. 



And so it goes on. The child gains wider knowledge from the appearance 

 of different objects, learns their names and practices them i. e., learns to make 

 the necessary movements of his organs of speech. 



