80 ELECTRO-PHYSIOLOGY CHAP. 



the spinal cord of the frog from about the 3rd to the 5th verte- 

 brae, divided the roots of all the spinal nerves except those of the 

 sciatic, and pushed in a small knife horizontally above the lumbar 

 swelling, so that it divided the dorsal and ventral halves of the 

 cord. If the knife were then drawn forward in the same 

 position to the upper boundary of the cord, there would be a free- 

 lobe, composed of the posterior columns, a greater or less propor- 

 tion of the lateral columns, and gray matter ; which, after 

 dividing its anterior and posterior ends, could be removed 

 altogether. In this way the whole posterior (dorsal) half of the 

 spinal cord, along with the entering sensory roots, was eliminated, 

 and the possibility of discharging reflex movements at the seat of 

 excitation excluded. If the isolated ventral part of the cord was 

 then mechanically excited, Van Deen sometimes obtained move- 

 ments of the hind-foot, which he at first believed to be due to 

 direct excitation of the anterior column. Meantime Stilling drew 

 attention to the possibility that the highly sensitive anterior roots 

 of the sciatic plexus might be excited in these experiments by 

 slight traction of the cord, and Van Deen himself, before the 

 publication of Stilling's work, had been led by new experiments 

 to the remarkable conclusion that neither the anterior column 

 nor the other parts of the spinal cord were excitable thus first 

 formulating a dogma destined to prevail in physiology for many a 

 decade. 



In subsequent demonstrations Van Deen did not even consider 

 it necessary to remove the upper dorsal half of the spinal cord, 

 but employed the uninjured medulla which protruded from the 

 vertebral canal. Mechanical, chemical, or electrical excitation of 

 the cephalic end failed, it was said, even with strong currents, to- 

 produce any symptoms of activity in the muscles of the posterior 

 extremities. 



Schiff (37) meantime, without knowing of Van Deen's earlier 

 publications, arrived at the same conclusions, as the result of 

 a series of experiments on the spinal cord of different warm- 

 blooded animals. Total insensibility of the paths which con- 

 duct painful influences (" sesthesodic "), and inexcitability of the 

 paths along which motor impulses travel (" kinesodic "), seem 

 here, too, to be the general rule. Schiff's experiments were in 

 the main analogous to the first of Van Deen's, since he removed 

 the posterior columns in the partially exposed cord for a distance 



