ON THE MAMMALIAN NERVOUS SYSTEM. 



455 



RIGHT Nerve connected. 



The effect in the mixed nerve of the Monkey is thus shown to be most strongly 

 evoked when the excitation is that of the posterior column on the same side as the 

 observed nerve. This preponderance over those effects which are evoked in a minor 

 degree from stimulation of the lateral of the same side and the posterior of the 

 opposite side is very marked when the stimulus is minimal. 



The two experiments thus quoted form two in a series similarly made upon six Cats 

 and five Monkeys, and the average results of all galvanometric deflections obtained in 

 these form the most reliable data from which to draw any conclusions as to the relations 

 between the amount of electrical change in the mixed nerve and the special regions of 

 the cord which were stimulated. We must, however, again discriminate between 

 effects evoked by stimuli of only just sufficient intensity to ensure their presence, 

 which we term minimal (i.e., 500 to 1000), and those which more strongly arouse 

 the region excited, maximal (i.e., 2000, occasionally 4000) ; hence, for every column 

 excited, we have the result of a minimal and a maximal stimulus. 



Moreover, it is obviously useless to designate which nerve is connected with the 

 galvanometer, if we place together 



A. All effects evoked by excitation of the posterior column which is on the same 

 side as the nerve. 



B. All effects due to excitation of the posterior column on the opposite side to the 

 nerve. 



C. Those due to stimulation of the lateral column on the same side. 



D. Those due to stimulation of the lateral column on the opposite side. 



Any alterations in the stimulation as to intensity and duration necessary in 

 different animals do not affect the value of any comparison between the quantitative 

 results of the members of each different group, since the stimulus was always the 

 same during any one set of observations, and each set included stimulation in regular 

 succession of all the different columns indicated. The total result of such observations 

 in the Oat is as follows : 



