. XII. XIII. EFFECTS ON SPINAL MARROW. 245 



I introduced the conductors into the very substance of these 

 organs, without perceiving either convulsions or signs of 

 pain. But by bringing the conductors in contact with the 

 tubercula quadrigemini, the crura cerebri, and medulla oblon- 

 gata, we obtain very violent convulsions throughout the 

 body, and the animal gives signs of suffering. 



Effects on the Spinal Marrow and the Roots of its Nerves. 

 In conjunction with Longet, I examined the action of the 

 electric current upon the roots of the spinal nerves, and on 

 the fasciculi of the spinal marrow. The following are the 

 results obtained. With the anterior roots, which are for 

 motion, there was, as usual, in the first period, contractions 

 produced both when we closed and when we interrupted 

 the circuit, whatever was the direction of the current. In 

 the second period of excitability, we obtained, by acting 

 upon the anterior roots, the opposite effect to that which 

 took place upon the mixed nerves; the inverse current 

 excited contractions in the first moments of its passage, and 

 none when it ceased ; the direct current, on the contrary, 

 produced them when it was interrupted, and not when we 

 closed it. It is unnecessary to add, that contractions were 

 never produced when we acted upon the posterior roots, 

 provided that we had divided the anterior ones. The an- 

 terior fasciculi of the spinal marrow offered the same phe- 

 nomena as the corresponding roots. These differences ap- 

 pear to me of the very highest importance. 



I have recently found that a mixed nerve, after having 

 been submitted to a great number of successive discharges, 

 such as can be obtained with an electro-magnetic machine, 

 presents, for a certain time, the phenomena of the anterior 

 roots now described. 



This study, I repeat, will be of the highest importance 

 for the physics of the nervous system ; and the facts related 

 lead us to assume that the differences obtained with different 



