502 



MKSSRS. F. GOTCH AND V. HORSLEY 



the phenomenon from the more general point of view expressed above until further 

 research shall make the question clearer. 



Meanwhile in this place we wish to add a few remarks on a curious result which we 

 occasionally obtained (and the meaning of which is very doubtful) by varying the 

 above-mentioned experimental procedure. 



As before, we connected the sciatic nerve with the galvanometer, and exposed the 

 cauda equina after section of the cord in the dorsal region. Each posterior root was 

 now excited in continuity with the cord, seriatim. The anterior roots were then cut, 

 and the excitation repeated. 



In this preparation, therefore, we had the arrangement indicated in the diagram. 

 (Fig. 24.) The first experiment of the kind was simple and uncomplicated, and may 

 therefore serve as an example. 



CAT (177). Sciatic Nerve and Roots of the Right Side prepared after Section of 



the Cord in the Dorsal Region. 



It will thus be seen that section of the anterior roots seemed to enormously 

 increase the effect in the nerve. We were quite at a loss to understand this result 

 and therefore repeated the experiments. We then found that this striking difference 

 was not always obtainable. In one experiment, for example, in which the section of 

 each anterior root alternated with excitations of the corresponding posterior root, the 

 rise of effect was only noted with one root viz., the 7th lumbar in which the effect 

 mounted from 130 to 160, 147, 250, whereas the other roots showed no rise. In this 

 experiment we noted that there was cooling of the- preparation, especially of the lower 

 roots. In a succeeding experiment (Cat, 182) we found that warming the cord had a 

 very noteworthy effect on the result, whereas warming the root had not. We then 

 made a fourth experiment (Cat, 268), in which the arrangement of the first was more 

 closely adhered to 



