514 MESSRS. P. GOTCH AND V. HORSLEY 



In the galvanometer, similarly, the lowest recorded deflection was 110, the highest 

 being over 300 and obviously conditioned by the duration of the convulsions. 



No comparison can be drawn between the magnitude of the deflections and those 

 obtained from the nerve, for the above and other reasons. In general they confirm the 

 validity of the views advanced, respecting the results obtained by electrical excita- 

 tion of the central nervous system as detailed in the foregoing chapters. 



An experiment in this connection may here be mentioned as of special interest 

 regarding the action of absinthe. The toxic action of this drug is unquestionably 

 excitatory as far as the highest nerve centres are concerned. FRANCOIS FRANCK * 

 found that it produced inexcitability of the cortex. One of us has previously 

 suggested that this is a question of dosage, in common with other narcotic agencies. 

 In the present series, while observing in one case the deflection produced by absinthe, we 

 superadded electrical excitation of the previously exposed cortex. The result (Cat 99) 

 was to notably increase the effect. Thus, while the chemical stimulus was actually 

 evoking a powerful discharge, the additional electrical excitation caused the centres 

 to produce still more kinetic energy. In this stage, therefore, the absinthe had not 

 exhausted the cortex. The additional effect was visible, both in the electrometer and 

 galvanometer, when either was switched on to the cord. 



SECTION 2. EXPERIMENTS (CONTROL) INCLUDING THE USE OF STRYCHNIA. 



The method of employing strychnia differed from that detailed in the case of 

 absinthe in one important particular, namely, that the spinal cord was severed from 

 its connection with the encephalon. The spinal cord in two Cats and one Monkey, 

 and the sciatic nerves and the posterior root in two Cats, were connected with the 

 galvanometer for observation of the excitatory electrical changes. The solution of 

 strychnia employed was a 1 per cent, solution of the acetate. It was injected into 

 the peritoneal cavity, and the toxic symptoms observed. The tetanic spasms, 

 like those obtained by absinthe, were of very varying force and duration, but gave far 

 higher readings than absinthe. We will return to this point later, and meanwhile 

 briefly state the results obtained. 



(1.) Electrical Effects in the Sciatic Nerves. The observation of the effects in the 

 Mammalian nerve during the discharges due to strychnia has furnished valuable 

 control results. We have, however, used the method to obtain by its means the 

 evidence referred to in the preceding chapter on the discharge of a nerve centre 

 backwards down the posterior root as well as the discharge down the anterior roots. 



(2.) Electrical Effects in Posterior Root. Similar changes to those in the nerve have 

 been obtained in the case of the posterior root. These have been already referred to 

 in Chapter XI., Section 3. 



(3) Electrical Effects in the Spinal Cord. When the spinal cord of an animal was 



* Loc. oit. 



