THE NATURE OF MUSCULAR SENSE. 1003 



Different exponents of " sensation of innervation " suggest different views 

 of its mechanism. The discharge of motor nerve cells, as per se of sensual 

 quality, is one suggestion (J. Miiller, 1 Helmholtz, 2 Wernicke, 3 and formerly 

 Wundt). 4 Another regards the motor nerve cell as possessing cellulifugal 

 branches besides its axon, and supposes the discbarge of the cell in that way to 

 run centripetally in the nervous system as well as outwardly ; among these, 

 Meynert, 5 H. Munk, 6 Exner, 7 and formerly, if I mistake not, Bastian. 8 

 For others, again, the motor nerve fibre itself is the site of refluent impulses 

 from as well as to muscle (Arnold, 9 Lewes 10 ), at once the afferent and efferent 

 channel for the " sensori-motor circuit" of Charles Bell. 11 The "sensation of 

 innervation " theory is connected with, but should be sharply distinguished 

 from, that cortical revival of sensible and remembered effects of past move- 

 ments, which seems to form the initiatory phase of the process of willed 

 muscular action. As a component of the muscular sense (kinesthetic) factor 

 of a willed movement, Bastian 1 - recognises a central process, revival of a 

 kinaesthetic image, and a peripheral process consisting of guiding kinaesthetic 

 impressions, which flow in from muscle, etc., and from eye, and influence the 

 motor discharge, although in a subconscious way. The former component is 

 psychologically a memory image of the sensations that accompanied the 

 movement when executed formerly, and especially when in process of being 

 learnt. To this position Miinsterberg 13 stands near. For Wundt, 14 centro- 

 motor elements lie in connection with centro-sensory, and these latter are 

 excited not only by influent impulses generated by peripheral muscular sense 

 organs, but also by the motor discharge in the centro-motor elements along 

 their central connections. This superficially approaches the immediate con- 

 sciousness of one's own movement, championed by Trendelenberg 15 and 

 George, 10 and combatted by Lotze ir and Harless. 18 A difference between 

 Bastian and Wundt lies in the former supposing that for the guiding kinaesthesis 

 there collaborate peripherally arising impressions with remembered peripherally 

 arisen ; while the latter supposes peripherally arising sensations to combine 

 with centrally arising, not distinctly stating those to be kinaesthetic revivals. 

 For Wundt the motor cerebral cell presumably reacts by cellulifugal processes 

 upon sensory cerebral cells ; Bastian years ago made a similar suggestion for 

 the motor cornual cells of the spinal cord, and Exner carries the latter notion 

 to extended use in the text and schemata of his recent " Entwurf." 7 



Since Hume, it has been admitted that the perceived results of our volition 

 are the outward ends obtained, and not the inward action of the neuro- 

 muscular machinery. But discrimination between weights is found possible 



1 "Handbuch d. Physiol.," 1840, Bd. ii. S. 500. 



2 " Physiol. Optik," 2te Aufl., 1896, S. 742, 947 ; and also in 1st edition. 



3 "Ges. Aufsatze," 1893, S. 6 ; " Grundziige d. physiol. Psychol.," Leipzig, 4te Aufl., 

 1894, Bd. i. S. 423 ; also in 3te Aufl., 1887. 



4 " Beitr. z. Theorie d. Sinneswahrnehmung," Leipzig, 1861, S. 409. 



5 " Das Zusammenwirken d. Gehirntheile," Verhandl. d. X. internal, med. Cong., 

 Berlin, 1890. 



6 "Ueber Funktionen d. Grosshirnrinde (Mitt. iii. 1878), 1881, S. 43, 52. 



7 " Entwurf z. einer physiol. Erklarung d. psych. Erscheinungen," Wien, 1894, S. 170. 



8 Brit. Med. Journ., London, 1869, vol. i. ; "Brain as an Organ of Mind," 1880. 

 a "Ueber die Verrichtung. d. Wurz. d. Riickenni.," 1844, S. 112. 



10 "Physiology of Common Life," Edinburgh, 1859, vol. ii. ; and in "Essays." 



11 Phil. Trans., London, 1830 ; and "The Hand," 3rd edition, London, 1834, p. 216. 



12 Proc. Hoy. Soc. London, 1895, vol. lviii. p. 89. 



13 "Beitr. z. exper. Psychol.," 1889, Heft 1 ; "Die Willenshandlung," Freiburg, 1888, 

 Bd. i. S. 145. 



14 "Grundziige d. physiol. Psychol.," 4te Aufl., 1893, Bd. i. S. 431 ; "Vorlesung. ueber 

 d. Mensch. und Thierseele," 2te Aufl., 1892, S. 145. 



15 "Logische Untersuch.," 2te Aufl., 1846, Bd. ii. S. 196. 

 1,5 "Lehrbueh d. Psychol.," Berlin, 1854, S. 231. 



17 "Med. Psychol.," 1852, S. 305 ; " Kleine Schriften," Bd. iii. S. 389. 



18 Fichte, Ztschr.f. Philos., N. S., Bd. xxxviii. S. 66. 



