[93] A few years ago one of the strongest arguments for the theory that the hemispheres are purely supernumerary was Soltmann's often-quoted observation that in new-born puppies the motor zone of the cortex is not excitable by electricity and only becomes so in the course of a fortnight, presumably after the experiences of the lower centres have educated it to motor duties. Paneth's later observations, however, seem to show that Soltmann may have been misled through overnarcotizing his victims (Pflüger's Archiv, vol. 37, p. 202). In the Neurologisches Centralblatt for 1889, p. 513, Bechterew returns to the subject on Soltmann's side without, however, noticing Paneth's work.
[94] Münsterberg (Die Willenshandlung, 1888, p. 134) challenges Meynert's scheme in toto, saying that whilst we have in our personal experience plenty of examples of acts which were at first voluntary becoming secondarily automatic and reflex, we have no conscious record of a single originally reflex act growing voluntary.—As far as conscious record is concerned, we could not possibly have it even if the Meynert scheme were wholly true, for the education of the hemispheres which that scheme postulates must in the nature of things antedate recollection. But it seems to me that Münsterberg's rejection of the scheme may possibly be correct as regards reflexes from the lower centres. Everywhere in this department of psychogenesis we are made to feel how ignorant we really are.
[95] Pflüger's Archiv, vol. 44, p. 230-1.
[96] Naturally, as Schiff long ago pointed out (Lehrb. d. Muskel-u. Nervenphysiologie, 1859, p. 213 ff.), the 'Rückenmarksseele,' if it now exist, can have no higher sense-consciousness, for its incoming currents are solely from the skin. But it may, in its dim way, both feel, prefer, and desire. See, for the view favorable to the text: G. H. Lewes, The Physiology of Common Life (1860), chap. ix. Goltz (Nervencentren des Frosches 1869, pp. 102-130) thinks that the frog's cord has no adaptative power. This may be the case in such experiments as his, because the beheaded frog's short span of life does not give it time to learn the new tricks asked for. But Rosenthal (Biologisches Centralblatt, vol. iv, p. 247) and Mendelssohn (Berlin Akad. Sitzungsberichte, 1885, p. 107) in their investigations on the simple reflexes of the frog's cord, show that there is some adaptation to new conditions, inasmuch as when usual paths of conduction are interrupted by a cut, new paths are taken. According to Rosenthal, these grow more pervious (i.e. require a smaller stimulus) in proportion as they are more often traversed.
[97] Whether this evolution takes place through the inheritance of habits acquired, or through the preservation of lucky variations, is an alternative which we need not discuss here. We shall consider it in the last chapter in the book. For our present purpose the modus operandi of the evolution makes no difference, provided it be admitted to occur.
[98] See Schrader's Observations, loc. cit.