ON THE MAMMALIAN NERVOUS SYSTEM. 513 



(1.) Excitation of the Intact Central Nervous System btj Absinthe. Electrical Effects 



in the Sciatic Nerve. 



The results obtained by this arrangement were as follows : 



(a.) Observations ivith the Galvanometer. The experiments were made on four Cats, 

 one to fifteen drops of absinthe being injected. The preliminary effects noted in the 

 galvanometer while as yet the spasms were limited to the upper anterior muscles of 

 the body amounted to small deflections, of which the following are examples : 4, 5, 5, 

 8, 10, 10, 13, 15. 



When, however, the toxic effect of the drug became more marked, and the 

 discharges summated produced a fully developed fit, as above described, then the 

 deflection of the galvanometer was notably increased, and ran up to maxima of 

 135, 150, 150, 185, 210, 272. 275, these averaging nearly 200. In smaller attacks, 

 but still generalised, the deflection varied from 45 to 85. With regard to the 

 magnitude of these deflections, it is to be noted that their large amounts are 

 doubtless due to the completely bilateral and prolonged character of the cortical 

 discharges and the continued effect on the galvanometer. 



(b.) Observations with the Electrometer. When during any one of the above 

 observations the electrodes in contact with the central end of the nerve were switched 

 over so as to bring it into connection with the electrometer, the effect was visible, but 

 varied notably in amount from a small movement of the mercurial meniscus to 1 

 division. 



It was thus abundantly clear that the employment of absinthe gave maximal 

 electromotive effects in the sciatic nerve through the overwhelming discharge of the 

 highest cortical centres, and the figures obtained from the galvanometric deflections 

 give a fair notion of the comparative magnitude of these discharges, the more 

 especially as the degree to which the epileptic discharge developed could be plainly 

 seen in the amount and duration of the spasm in the neighbouring muscles. This 

 being so, it is, of course, hardly necessary to add that the cessation of the convulsion 

 was synchronous with a halt in the swing of the galvanometer needle. 



(2.) Excitation of the Nervous System by Absinthe. Electrical Clianges in the 



Spinal Cord. 



As might have been anticipated, the electrical effects observed in the spinal cord 

 when the central mechanisms were excited by a diffuse stimulus, such as that of 

 absinthe in the circulation, were larger than that witnessed in the peripheral nerve. 



We have made four experiments in Cats, and one in the Monkey (Macacus rhesus], 

 and have usually measured the effect with the electrometer. With this instrument 

 the excursions of the mercury were very marked, varying from slight movement in 

 the case of initial spasms to excursions of even five divisions in severe fits. 



MDCCCXCI.-B. 3 U 



