184 THE POPULAR SCIENCE MONTHLY. 



serves mental operations, and that there are no parts specially devoted 

 to any particular functions. This has been recently expressed by so 

 high an authority as Prof. Sequard. The idea rests chiefly on the 

 numerous facts of disease with which we are acquainted. There are 

 cases where extensive tracts of brain are destroyed by disease, or re- 

 moved after a fracture, apparently with no result as regards the mind 

 of the individual. Along with these facts we have others which are 

 very curious, and which hardly seem to agree with this doctrine. One 

 of these is, that when a certain part of the brain is diseased, in apha- 

 sia, the individual is unable to express himself in words. Other curi- 

 ous phenomena have been well described by Dr. Hughlings Jackson, 

 viz., that certain tumors or pathological lesions in particular parts of 

 the brain give rise, by the irritation which they keep up, to epilepti- 

 form convulsions of the whole of one side, or of the arm, or leg, or the 

 muscles of the face ; and, from studying the way in which these con- 

 vulsions show themselves, he was able to localize very accurately the 

 seat of the lesion. 



The great difficulty in the study of the function of the brain has 

 been, in the want of a proper method. When we study the function 

 of a nerve, we make our experiments in two ways : In the first place, 

 we irritate the nerve by scratching or by electricity, or by chemical 

 action, and observe the effect; and, in the second place, we cut the 

 nerve, and observe what is lost. In regard to the brain and nervous 

 system, the method has been almost entirely, until recently, the method 

 of section. It has been stated by physiologists that it is impossible to 

 excite the brain into action by any stimulus that may be applied to it, 

 even that of an electric current ; they have, therefore, adopted the 

 method of destroying parts of the brain. This method is liable to 

 many fallacies. The brain is such a complex organ, that to destroy 

 one part is necessarily to destroy many other parts, and the phenom- 

 ena are so complex, that one cannot attribute their loss to the failure 

 only of the parts which the physiologists have attempted to destroy. 



About three years ago, two German physiologists, Fritsch and 

 Hitzig, by passing galvanic currents through parts of the brains of 

 dogs, obtained various movements of the limbs, such as adduction, 

 flexion, and extension. They thus discovered an important method 

 of research, but they did not pursue their experiments to the extent 

 that they might have done, and perhaps did not exactly appreciate the 

 significance of the facts at which they had arrived. 



I was led to the experiments which I shall have to explain, by the 

 effects of epilepsy and of chorea, which have been explained to depend 

 upon irritation of parts of the brain. I endeavored to imitate the 

 effects of disease on the lower animals, and determined to adopt the 

 plan of stimulating the parts of the brain by electricity, after the man- 

 ner described by Fritsch and Hitzig. 



I operated on nearly a hundred animals of all classes — fish, frogs, 



