336 MESSRS. F. GOTCH AND V. HORSLEY 



The largest effects we have ever seen in the nerve in consequence of cortical 

 excitation have been obtained by the use of absinthe. The powerful general fits 

 which followed the introduction into the blood of this drug being evidenced in two 

 animals (Cat) by effects which have amounted to 272 scale. It need hardly be 

 pointed out that such fits are of extremely prolonged character, and that in the spinal 

 cord electrical changes occur which give deflections in very many cases too large to be 

 read (off screen). 



Cortical Localisation as Evidenced by Electrical Changes in the Nerve. 



The electrical changes in the nerve, as evidenced by the galvanometer, although 

 small, are quite definite, and afford additional proof of the localisation of cerebral 

 representation. Thus, when an adequate stimulus was employed, which was, 

 however, only intense enough to evoke unilateral muscular contractions, the electrical 

 change in the nerve was entirely confined to that on the opposite side to the excited 

 cortex. This subject will be discussed in detail in Chapter VII., which deals with 

 bilaterality of representation. It may, however, be pointed out that no other operative 

 interference than that already described as necessary for cortex and nerve exposure 

 having been performed, it is perfectly evident that if the stimulus was maximal, as it 

 usually was in this experiment, a bilateral fit could and did happen, so that from one 

 nerve an effect might be and was obtained due to discharge of both hemispheres. 



It is, moreover, interesting from the point of view both of control and of localisa 

 tion, that in cases where a strength of stimulus which did not evoke a general 

 discharge was employed, whilst the application of the stimulus to the so-called lower 

 limb area of the Cat produced definite electrical changes in the nerve, its application 

 to the focus of representation of the upper limb evoked little or no change, even 

 though the stimulus was followed by marked epileptic convulsions in the upper 

 limbs. The localisation of the foci of representation of the movements of upper and 

 lower limbs in the Carnivora, which has been determined by other observers, is thus 

 corroborated by the use of the present method. 



CHAPTER VI. -ON THE ELECTRICAL EFFECTS EVOKED IN THE SPINAL CORD AND 

 MIXED NERVES BY EXCITATION OF THE CORONA RADIATA. 



EXCITATION OF CORONA EADIATA. 

 1. Electrical Changes in the Spinal Cord. 



We will consider first the general character of the changes as evidenced by the 

 movement of the capillary electrometer. 



