of Movements in the Lumbar Region of the Spinal Cord. 249 



of the stimulus whether only a part or the whole of these move- 

 ments resulted. Similarly, with regard to the lateral extent of 

 the areas mentioned above, although, of course, a stroog stimulus 

 caused movement in all parts named, yet in each case it was quite 

 definite that the area, stimulation of which produced movement in 

 the tail, was nearer the middle line than that for the hamstrings, 

 the area for the hamstrings nearer the middle line than that for 

 flexion of the hip, and this median of that which caused lateral 

 flexion of the side. Hence these results demonstrate from a func- 

 tional standpoint the anatomical arrangement which has been 

 described by various writers Ramon-y-Cajal, Kolliker. Grolgi, &c. 



As in the dog, the knee jerks were found not only present, but 

 even exaggerated, after the cord had been completely divided. 



Also section of the cord caused increased excitability of the parts 

 below section, but abolished the movement produced by stimulation 

 of the first or second or third posterior roots below the level of the 

 section, and the more oblique the position of the posterior root fibres 

 in contact with the cord, the greater the interval affected in this 

 manner. 



On the Production of Movement by Stimulation of the Anterior and 

 Posterior Spinal Roots in the Monkey. 



The general results obtained by excitation of the spinal roots in 

 the monkey were the same as those in the dog. As already known 

 (Sherrington, Risien Russell) stimulation of the third lumbar to the 

 first or second sacral anterior roots (inclusive) alone produces move- 

 ment in the lower limb, yet, on stimulation of the posterior roots of 

 the twelfth dorsal to the second sacral inclusive, it was found that 

 movement resulted in the lower limb, and in the latter case the bulk 

 of the movement produced is that of flexion. 



Summary and Conclusion. 



1. Relationship of Posterior Roots to Reflex Kincesthetic Centres. It 

 appears from the foregoing experiments to be definitely established 

 that any reflex centre derives its chief afferent impulses from a nerve 

 root which enters the cord, as a rule, about two segments higher, 

 i.e., on the cephalic side. This generalisation, established by the 

 method of excitation, is confirmed by anatomical and pathological 

 considerations. 



2. Lateral Arrangement of Fibres in Burdach's Column. The fibres 

 of the postero-external column are arranged in a definite and constant 

 order from within out, the innermost fibres (i.e., those nearest the 

 middle line) representing the most distal portions of the tail and 

 lower limb and the outermost the proximal segments of the limbs. 



