864 THE SPINAL CORD. 



lateral column, 1 and on arriving at the spinal vesical centre gives branch 

 paths across the median sagittal plane of the cord, forming therefore 

 bilateral connection with the local centre, which is itself bilateral. The 

 ascending path linking the sense organs of the hind-limbs with the 

 bulbar vasomotor centre and the descending path from the latter to the 

 thoracic efferent root cells of the vascular musculature, lie both of them in 

 the lateral column, 2 the descending in that of the side homonymous with 

 their main ending, the ascending perhaps mainly in the side crossed from 

 the peripheral sense organs possessing access to them (see below, p. 867). 



Observations with the method of Wallerian degeneration yield clearly 

 one negative point in regard to the ventro-lateral column, namely, that 

 none of its fibres are afferent root cell fibres. They furnish also positive 

 evidence that of its fibres many of the ascending pass to the cerebellum, 

 entering it on the same side as the column in which they lie; and that 

 probably a certain smaller number pass to the mesencephalon and dien- 

 cephalon, as also to the upper part of the spinal cord itself. Of the ventral 

 portion of the ventro-lateral column, especially its part between the 

 ventral fissure and the exit of the ventral root bundles, little is known 

 relative to function. Bilateral section of this region produces, so far as 

 observed, no detectable impairment in the animals examined. 3 Klir- 

 schner, 4 Longet, 5 Volkmann 6 found mechanical and weak faradic excita- 

 tion of this region, or above it, when it alone of the whole thickness of 

 the cord remained, produce movements of the muscles far behind the 

 level of section. Brown-Sequard concluded, after a similar transection, 

 that some signs of sensation were still elicitable from regions behind the 

 lesion. In agreement with these observations, the Wallerian degenera- 

 tion method demonstrates fibres descending in this column from both 

 roof and floor of mesencephalon, 7 from metencephalon, 8 and in mammals 

 from the mantle of the hemisphere itself. The degeneration method 

 also shows fibres ascending in this column in large numbers from spinal 

 cells even many segments posterior ; 9 these fibres are for the most part 

 small, the descending for the most part large. 



It was long ago 10 known that an effect of lateral semisection of the 

 cord is to impair the motor and sentient functions of the parts of the 

 body innervated by the spinal nerves behind and on the same side as 

 the section. It was more recently n noted that the impaired motility 

 becomes in course of time partly restored. Further study of the motor 

 and sensory defects led to the belief that, while the path subserving 

 intentional movement descends the same side of the cord as the muscles 

 which contract, the sensitivity of each half the body involves a double 



I C. C. Stewart, Am. Journ. PhysioL, Boston, vol. ii. p. 198; also I. Ott, Med. Bull., 

 Phila., 1894, vol. xvi. p. 410 ; Mosso and Pellacani, Atti d. r. AccacL d. Lincei. CL di sc. 

 fis., mat. e nat., Roma, 1881, tomo xii. p. 3 ; Budge, "Untersuch. ueber d. Xervensystem," 

 1859, Bd. i. S. 184 ; Ztschr. f. rat. Med., 1864 (3), Bd. xxi. S. 1. 



3 Dittmar, Arb. a. d. physioL AnsL zu Leipzig, 1873, S. 479. 



3 Miescher, op. cit. ; Woroschiloff, op. cit. 



4 In the translation of Marshall Hall's "Memoirs," Marburg, 1840. 



5 "Systeme nerveux," Paris, 1860, tome ii. 



6 Wagner's " Handwbrterbuch ;" soalsoFick, Arch.f. d. ges. PhysioL, Bonn, 1869, Bd. ii. 



7 Held, Arch. f. Anat. u. EntwcUngsgesch. , Leipzig, 1893; Boyce, Phil. Trans., 

 London, vol. clxxxvi. B, p. 321. 



8 Marchi, Ferrier and Turner, A. Thomas, etc., vide supra, p. 808. 



9 Sherrington, Journ. PhysioL, Cambridge and London, 1893, vol. xiv. 



10 Hippocrates, -rrpoprjTtKuv. /3'. xxvi. ; Galen, "De locis affectis" (young pigs and mon- 

 keys), vol. iv. cap. 4 ; " De administ.," vol. viii. pp. 7, 8, 9. 



II Cooper, Med.-CMr. Trans., London (dog), 1803, vol. i. p. 200. 



