ON VOLUNTARY MOVEMENTS. 671 



the same side as the hemisphere stimulated may move also. But such an 

 abnormal movement of the same side lias not the same characters as the 

 proper movement of the crossed limb. Instead of being an orderly coordi- 

 nate movement, it is a more simple, either tetanic or perhaps tonic, or 

 rhythmic, clouic, contraction of the muscles. Obviously its mechanism is 

 of a different nature from that by which the proper movement of the crossed 

 limb is effected ; but it is important to bear in mind that a movement of 

 the uncrossed limb may take place ; and further, that the abnormal condi- 

 tions continuing, similar movements of an uncoordinated character may 

 spread to the hind limb and other parts of the crossed side, though the stimu- 

 lation be still confined to the arm area, then to other parts of the uncrossed 

 side, until, as we have said, the whole body is thrown into epileptiform con- 

 vulsions. This feature must not be forgotten. In fact, it may be fairly 

 insisted upon that while we may speak of a particular coordinate movement 

 as being the normal outcome of an ordinary careful stimulation of a par- 

 ticular 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, etc. The movements of the same part may 

 be further distinguished by means of the nomenclature usually adopted in 

 speaking of muscular movements, such as flexion, extension, abduction, 

 adduction, etc. ; so that, within the area bearing the name of some particular 

 part such as the wrist, for instance we have to distinguish 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 cor- 

 responding 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 localization which obtains in the cortex is essentially a 

 localization corresponding not to parts of the body or to nerves or to mus- 

 cles, but to movements. In considering this point it must be remembered 

 how rude and barbarous a method of stimulation is that of applying electrodes 

 to the surface of the gray matter compared with the natural stimulation which 

 takes place during cerebral action ; the one probably is about as much like 

 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 characters and purpose of each movement, and by 

 these alone; on the other hand, we should find very decided limits to the 

 number and kind of movements which we could evoke, limits fixed in the 

 case of each subject partly by inherited organization, partly by the training 

 of the individual. 



Some such results of refined experimentation are, indeed, already fore- 

 shadowed by the rude results of our present rough methods. The move- 

 ments which usually follow stimulation of the motor region, and which we 

 have described as flexion, etc., are, so to speak, the elementary factors of 



