570 WILL AND 



Nerves to the requisite groups of Muscles. The upper 

 part of the route still remains, however, to be specified . 

 We have to consider whether it is from special parts 

 of the surface of the Cerebral Hemispheres and if so, 

 from what parts the before-mentioned Intellectual Incita- 

 tions (which in their subjective embodiment are commonly 

 known as ' Will ' or ' Volition ') pass downwards to the 

 great Motor Ganglia the Corpora Striata ? 



Previous to the experiments of Fritsch and Hitzig 

 (1870) and of Ferrier (1873) it had been generally believed 

 that physical irritations of the surfaces of the Cerebral 

 Hemispheres were not capable of evoking any definite 

 Movements. These investigators, however, found that 

 some definite Movements were capable of being produced 

 by electric irritation ; and that though the Movements 

 varied in character they were more or less similar when 

 the same limited regions of the surface Grey Matter were, 

 on. different occasions, stimulated to a like extent. Fritsch 

 and Hitzig originally obtained such results principally by 

 making use of weak ' voltaic ' currents ; whilst Ferrier's 

 subsequent though more extensive observations were made 

 with the aid of weak 'induced' currents. The Move- 

 ments thus produced by the stimulation of certain parts, 

 were found, on the other hand, to be abolished when theso 

 same parts of the Cerebral Cortex had been destroyed 

 that is, such Movements were no longer capable of being 

 performed by the animal, either of its own accord or as a 

 sequence of external stimulation. 



Some of the principal facts bearing upon this question 

 of the excitation or abolition of definite Movements as a 

 result of the stimulation or destruction of definite portions 

 of the cortex of the Brain in Monkeys * may, perhaps, be 



* The Movements of these animals being most allied to those of 

 Man, and their Brains being also most similar to his, it will bd 



