348 INNERVATION. [CHAP. XI. 



brain in their numerous radiations, all these several parts are linked 

 together for the common purposes of volition, and constitute a great 

 centre of voluntary actions, amenable to the influence of the will 

 at every point. 



It has been pretty generally admitted by anatomists, that both 

 the corpora striata and the anterior pyramids are concerned in 

 voluntary movements. The motor tracts of Bell were regarded by 

 that physiologist as passing upwards from the anterior columns of 

 the cord to the corpora striata, and, after traversing those bodies, 

 as diverging into the fibrous matter of the hemispheres ; and the 

 fact of the origin of certain motor nerves, in connexion with those 

 fibres, was considered to be very favourable to this view. The 

 decussation of the pyramids, likewise, so illustrative of the cross 

 influence of the brain in lesions sufficient to produce paralysis, 

 has been looked upon as an additional indication of the motor 

 influence of these parts. 



The invariable occurrence of paralysis as the result of lesion, even 

 of slight amount, in the corpora striata, must be regarded as a 

 fact of strong import in reference to the motor functions of these 

 bodies. 



Nor is this fact at all incompatible with the statements made by 

 all experimenters, that simple section of the corpus striatum does 

 not occasion either marked paralysis or convulsion ; and that in 

 cutting away the different segments of the brain, beginning with 

 the hemispheres, convulsions are not excited until the region of the 

 mesocephale are involved. The influence of the corpora striata is 

 not upon the nerves directly, but upon the segments of the medulla 

 oblongata or of the spinal cord, and, through them, upon the nerves 

 which arise from them. Were the nerve-fibres continued up into 

 the corpora striata, according to an opinion which has been long 

 prevalent, there would be no good reason for supposing that they 

 should lose in the brain that excitability to physical stimuli which 

 they are known to possess in the spinal cord, and at their peripheral 

 distribution. 



The latest experiments, which are those of Longet and Lafargue, 

 agree in the following result, which is not at variance with that 

 obtained by Flourens. The animals remain immoveable after the 

 removal of the corpora striata, whether those bodies have been 

 removed alone or in conjunction with the hemispheres ; nor do they 

 shew any disposition to move, unless strongly excited by some 

 external stimulus. None of these observers had noticed the irre- 

 sistible tendency to rapid propulsion, which was described by 



