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MESSRS. F. GOTCH AND V. HORSLEY 

 C. CORD Excitation. Cord severed from Cortex. 



These results indicate (1) that the rise in the difference is occasioned not merely by 

 the direct application of the stimulating agent to the cord, but as a consequence of 

 the presence of a series of excitatory processes, whether these are produced by nerve 

 impulses entering below by afferent channels, or from above by cortical efferent ones. 

 This conclusion is supported by the fact that a similar rise follows a large reflex 

 discharge of energy from the cord, when this is produced in the strychnised animal 

 by sensory stimulation. 



(2.) They also show that the rise is least in the case of the excitatory cord changes 

 evoked by cortical stimulation, in which case the limit of rise is not only small, but 

 soon attained, the average rise in the instances given under A being '003, the 

 maximum = '005, the minimum = '001. When the sciatic nerve or posterior root of 

 the cord (severed from the brain) is excited, the rise is seen to be much more 

 pronounced, being on the average '005, maximum 'Oil, minimum '003. Finally, 

 when the columns of the cord itself are excited, the rise is greater, the average being 

 006, maximum '013, minimum '002. (The average rise in this case would be still 

 greater if the three very low and exceptional readings of '002 were omitted from the 

 table ; it would then be '0075.) In the same experiment performed on the Monkey 

 (232) the rise in half an hour following twelve excitations was '006. 



It would thus appear that one of the main features in the rise is the extent to 

 which the nerve structures in the cord are thrown into activity ; the result of 

 cortical excitation is to awaken impulses in a more limited area of the cord than is the 

 case with excitation of the sciatic afferent nerve fibres, and this latter does not cause 

 such a widespread awakening as is produced by direct cord stimulation. 



From these results alone no conclusions of a definite kind can be drawn as to the 

 relations subsisting between the cord and the brain on the one hand, and the cord 

 and the nerves on the other, but if the amount of resting difference may be truly 



