362 MESSRS. F. GOTCH AND V, HORSLEY 



and four cases in which the effect was under 10, and averaged only 4. It is, there 

 fore, only by including cases of bilateral effects produced by powerful tonic discharges 

 that the above total average is so comparatively high. 



If, therefore, these higher figures were separated from the Table, we should find that 

 the average effect on the same side would be not more than one-sixth of that on the 

 opposite side ; whilst, with evident and powerful bilateral discharges, the former effect 

 amounts to one-half of the latter. 



Summary of Facts. 



The facts brought forward in the preceding pages seem to show that it is possible 

 to obtain completely unilateral effects in both spinal cord and nerve when one 

 cerebral hemisphere is excited, but that an increase in the intensity of the stimulus, 

 and a diminution in the degree of narcosis, favour the production of bilateral effects 

 the inequality between the crossed and uncrossed effect becoming less and less marked 

 in proportion as these favouring circumstances are augmented. 



The conclusion to which the previous observations seemed to tend, that in one 

 cortex bilateral representation of the limbs exists, does not seem to be supported by 

 the present experiments, since such bilateral effects as may be witnessed are specially 

 brought out by agencies which may be supposed to bring into play other portions of 

 the central nervous system, particularly the opposite excitable cortex, the cerebellum, 

 and basal structures. We feel, however, that without definitely proving this, our 

 experiments have the result of making the question of bilateral representation in 

 one cortex an open one, at least for the Carnivora. 



To this position all we wish to add is our view that the weight of evidence goes to 

 show that, where the excitation is properly limited to the cortico-pyramidal system, 

 unilaterality of representation of the lower limb muscles appears to exist. 



How far this is correct only further researches by the electrical method will, we 

 believe, be successful in showing ; and we hope that others will forward the investiga 

 tion of this point. 



