CHAP, ii.] THE BRAIN. 7.VJ 



normal outcome of an ordinary careful stimulation of a particu- 

 lar area in a normal condition, it is no less true that diffuse 

 uncoordinated movements, culminating in general epileptiform 

 convulsions, are the natural outcome of the stimulation of any 

 area in an abnormal condition. And in attempting to form any 

 opinion of the nature of the first act, we must bear the second 

 in mind. 



As we said above, the movements resulting from cortical 

 stimulation are most conveniently described in terms of parts of 

 the body, of the arm, of the thumb, of the tongue, &c. The 

 movements of the same part may be further distinguished by 

 means of the nomenclature usually adopted in speaking of mus- 

 cular movements, such as flexion, extension, abduction, adduc- 

 tion, &c.; so that, within the area bearing the name of some 

 particular part, such as the wrist for instance, we have to distin- 

 guish an area for the flexion, and another for the extension of 

 that joint ; and in like manner in reference to other parts. But 

 it will be readily understood that it is easier to map out the 

 area for a particular part than to distinguish the areas corre- 

 sponding to the several movements of that part. Hence the 

 nomenclature usually adopted in speaking of the motor region 

 is one based on the parts of the body moved rather than on 

 the character of the movements. The more closely however 

 the movements in question are studied, the more probable it 

 appears that the localisation which obtains in the cortex is 

 essentially a localisation corresponding not to parts of the 

 body, or to nerves, or to muscles, but to movements. In con- 

 sidering this point it m\ist be remembered how rude and bar- 

 barous a method of stimulation is that of applying electrodes 

 to the surface of the grey matter compared with the natural 

 stimulation which takes place during cerebral action ; the one 

 probably is about as much alike the other, as is striking the keys 

 of a piano at a distance with a broomstick to the execution of a 

 skilled musician. Were it in our power to stimulate the cortex 

 in any way at all approaching the natural method, we should in 

 all probability arrive at two results ; on the one hand we should 

 be able to produce at will a variety of movements of different 

 degrees of complexity, some very simple, others very complex, 

 and for these we should have to use names suggested by the char- 

 acters and purpose of each movement, and ny these alone ; on 

 the other hand we should find very decided limits to the num- 

 ber and kind of movements which we could evoke, limits fixed 

 in the case of each subject partly by inherited organisation, 

 partly by the training of the individual. 



Some such results of refined experimentation are indeed al- 

 ready foreshadowed by the rude results of our present rough 

 methods. The movements which usually follow stimulation of 

 the motor region, and which we have described as flexion, &e, 



