878 THE SPINAL CORD. 



dorsal column, and of the grey mater consecutive to amputation of a 

 limb. Of the spinal cell groups in the limb region, one belonging to 

 the motor root cell system appears to suffer more than the rest. This is 

 the dorsal-lateral group in the ventral horn, — which there is reason to 

 think innervates in the crural region the muscles of the foot, in the 

 brachial region the muscles of the hand. Whether the amputation 

 of the limb has been at wrist or shoulder, at ankle or hip, this is the 

 group that exhibits the chief atrophy. It is probably only after 

 functional influence of one nerve cell on another, or on a peripheral 

 tissue, has become established, that the nutrition of the latter is affected 

 by the action of the former. In an amyelous foetus, possessing of 

 course no efferent spinal roots at all, the skeletal musculature may 

 appear as well developed as in a normal foetus of similar term. 1 



Trophic influence in a direction contrary in sense to the ordinary functional 

 relationship and connection, is very obscure. The herpes zoster due to an 

 inflamed spinal root ganglion, unless, as is possible, of reflex production, seems 

 to be an example of this exercise of influence, so to say, "against stream." 

 The cutting of the facial nerve is said to cause recognisable alteration of the 

 structure of the root cells of that purely motor nerve. The section of a ventral 

 spinal root seems also to affect its cells of origin. 2 Transection of the spinal 

 cord in young animals entails even in course of a few weeks atrophy of 

 the cell-group of Clarke's column. These injuries are, it is true, applied 

 actually to a portion of the cell itself which they are found to alter ; but the phe- 

 nomenon, which is one now under active investigation, admits at present of little 

 that is satisfactory in way of explanation. The tearing out of the motor roots 

 is said to be more productive of the central changes than is their simple section. 



Eegeneration of the Spinal Cord. 



It has been asserted that the spinal cord of the frog 3 and pigeon, 4 after 

 complete transection, may, in the course of a few weeks, show reunion, nerve 

 cells and nerve fibres existing in the tissue bridging the lesion. Figures 5 

 given of the cells believed to be nervous suggest connective tissue fibroblasts 

 or neuroglia cells rather than nerve cells. The supposed regeneration is in 

 accord with a number of observations of a not altogether convincing kind, 

 none of them recent, in which restitution of "volitional movement" and 

 of " conscious reaction " in relation with the regions behind the transection, 

 appeared to occur. 6 It must be remembered that some recovery of function 

 is possible without regeneration of the tissue, 7 and reflex movements can be 

 only with difficulty discriminated from intentional. 



The whole question bases itself on the discovery by Spallanzani, in 1768, 8 



1 Sherrington, Journ. Physiol., Cambridge and London, 1894, vol. xvii. ; v. Leonava, 

 Neurol. CerUralbl., Leipzig, 1896, Bd. xv. 



-Warrington, loc. cit. ; Marinesco, Neurol. Ccnlralbl., Leipzig, 1898. 



3 Masius and Van Lair, Centralbl. f. d. med. Wissensch., Berlin, 1869, No. 39; Bull. 

 Acad. roy. de mid. de Belg., Bruxelles, 1870, tome xxi. (Mem. couronnee). 



4 Brovvn-Sequard, ' Exper. sur les plaies d. 1. moelle ^piniere," Gaz. mid. de Paris, 

 1849, p. 232 ; " Regen. d. tiss. d. 1. moelle epiniere," ibid., 1850, p. 250 ; " Sur plusieurs 

 cas de retour des fonctions. etc.," ibid., 1851, p. 477. 



6 Masius and Van Lair, Bull. Acad. roy. de mid. de Belg., Bruxelles, 1870, tome xxi. pi. 

 ii. fig. 5. 



6 Prochaska. "Opera Minora, "Vienna, 1800 ; Legallois, "CEuvres," Paris, 1824 ;Flourens, 

 Ann. d. sc. nat., Paris, 1828, tome xiii. p. 113 (in the duck); Ollivier, "Traite" d. maladies 

 del. moelle Epiniere," tomei. p. 249, 3rd edition (in the cat) ; Arnemann, Journ. compl. du 

 diet. d. sc. med., Paris, 1836, tome xxv. p. 214 (original, a rare work) ; " Versuche ueber d. 

 Regeneration," Gottingen, 1797; Dentan, " Inaug. Diss.," Bern, 1873; Masius and Van 

 Lair, loc. cit. ; Brown-Sequard, loc. cit. 7 See section on spinal conduction, p. 865, supra. 



8 " Prodromi sulle riproduzioni animali : Riproduzione della coda del girino," Modena, 

 1768. 



