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182 Stieda, Bau des centralen Nervensystem der Amphibien und Reptilien, 1875, p. 41.
183 Butzke, in Archiv fĂĽr mikroskopische Anatomie, Bd. III. Heft 3, p. 596.
184 Except in the rare cases where there is anastomosis of the muscle-fibres; as, for example, in the heart. [According to Engelmann’s remarkable researches, the muscles of the heart form a continuum, so that irritation is propagated from one to the other: Pflüger’s Archiv, 1875, p. 465. This is indubitably the case in the embryonic heart, as Eckhard pointed out.] This I hold to be the main cause of its rhythmic pulsation after removal from the body. Whatever influence the ganglia may have in exciting this pulsation, such influence would be powerless were not the muscles so connected; as may be seen in the other organs which are richly supplied with ganglia, yet do not move spontaneously; and in organs (such as the ureter or the embryonic heart, and the hearts of invertebrata) which move spontaneously, yet have no ganglia.
185 Schröder van der Kolk, Bau und Funktionen der Med. Spinalis, p. 67.
186 It is very instructive to learn that for some six months or so the rat is quite incapable of correctly localizing the pain.
187 Vulpian, Leçons sur le Système Nerveux, p. 288. The experiment has been confirmed by Rosenthal, and by Bidder (Archiv für Anatomie, 1865, p. 246), who first (in 1842) attempted this union of different nerves, but arrived at negative results; as did Schiff (Lehrbuch der Physiol, 1859, p. 134) and Gluge et Thiernesse (Annales des Sciences Naturelles, 1859, p. 181).
188 Sachs, in the Archiv fĂĽr Anat., 1874, pp. 195, sq.
189 Laplace, Essai Philos. sur les Probabilités, p. 239.
190 The mode of termination of nerves in muscles is still a point on which histologists disagree; probably because there is no abrupt termination, but a blending of the one tissue with the other. In the Tardigrades, for example, there is actually no appreciable distinction between nerve and muscle at the point of insertion of the nerve; and if in the higher animals there is an appreciable difference between nerve and muscle, there is an inseparable blending of undifferentiated substance at their point of junction. [According to Engelmann’s recent researches, there seems good reason to suppose that muscles are composed of contractile substance and a substance which is a modification of axis-cylinder substance; the first being doubly refracting, the second isotropic: Pflüger’s Archiv, 1875, p. 432.]
191 Schiff, Lehrbuch, p. 73.
192 Freusberg observed that the reflex movements in the legs of a dog whose spine had been divided were considerably lessened after food or drink. They fell from 95 to 46 pendulum-beats in a minute after a litre of water had been drunk. See his instructive memoir, Reflex-Lähmungen beim Hunde, in Pflüger’s Archiv, 1874, p. 369.
193 M. Herzen thus describes the effects of stimulating the vagus with varying intensities: “Si l’on se sert de l’appareil de Dubois Raymond, on commence par appliquer une irritation tellement faible qu’elle ne produit aucun effet; on rapproche alors peu à peu lea deux bobines de l’appareil avec le plus grand soin, par fractions de centimètres, par millimètres s’il le faut, et l’on trouve ainsi le degré d’irritation qui accelère les battements du cœur et qui produit le maximum de pulsations dans l’unité de temps admise pour l’expérience. Quand on est là il suffit d’un millimètre de plus pour faire disparaître l’augmentation, un autre millimètre peut produire une diminution, et un troisième peut arrêter le cœur complètement. En reculant alors, en éloignant peu à peu les deux bobines, on rètourne à la force qui produit l’augmentation des battements.” Herzen, Expériences sur les Centres Modérateurs de l’Action Réflexe, 1864, p. 68. There have been serious doubts thrown on these experiments; but several experimenters have confirmed their exactness. Quite recently they have been confirmed by Bulgheri, Il Morgagni, VIII.; and by Arloing and Tripier, Archives de Physiologie, 1872, IV. p. 418. It must be confessed, however, that the whole subject of the heart’s innervation is at present very imperfectly understood.
194 Cayrade, Recherches sur les Mouvements RĂ©flexes, 1864, p. 58.
195 A frog’s brain is removed, and the body then suspended by the lower jaw, the legs are allowed to dip into a slightly acidulated liquid, the chemical action of which stimulates the skin.
196 I saw a patient in the Berlin Charité whose face and left hand were in a constant state of convulsive twitching, but no sooner was a scar on the left hand (where the nerve had been divided) firmly pressed than the twitchings ceased, and pain was felt; on removal of the pressure, pain ceased and the twitchings returned.
197 Pflüger’s Archiv, 1875. No one interested in the Reflex Theory should omit a careful study of the papers by Freusberg and Goltz. I have drawn freely from them.
198 Sir James Paget has an interesting collection of facts which illustrate this Law of Arrest, in his paper on “Stammering with other Organs than those of Speech,” British Medical Journal, 1868, Vol. II. p. 437, reprinted in his Clinical Lectures and Essays, 1875, p. 77.
199 Archives de Physiol., 1868, p. 157.
200 West Riding Lunatic Asylum Reports, 1874, p. 200.
201 Claude Bernard, Système Nerveux, I. 383.
202 See the excellent remarks of Dr. Lauder Brunton on this point in his paper on Inhibition in the West Riding Lunatic Asylum Reports, 1874, p. 180.
203 The interesting question of interference has been experimentally treated by Wundt in his recently published Mechanik der Nerven, 1876, and theoretically as wave-movement by Medem, GrundzĂĽge einer exakten Psychologie, 1876.
204 On the distinction between first notions and theoretic conceptions, see Problems of Life and Mind, Vol. II. p. 277.
205 Not transcendental and a priori, as Kant teaches; but immanent in Feeling.
206 The reader will understand that although mechanical relations are modes of Feeling, as all other relations are, yet their aspect is exclusively objective, referring to objects ideally detached from subjects.
207 Antoine Cros, Les Fonctions supérieures du Système nerveux, 1875, p. 85.
208 The solution offered in the present chapter was first offered in Problems of Life and Mind, 1875, II. 465, sq. I mention this because since the publication of that volume other writers have expressed the same ideas, sometimes using my language and illustrations: e. g. M. Taine in the Revue Philosophique, January, 1877, art., Les Vibrations cérébrales et la Pensée.
209 Problems of Life and Mind, Vol. II. pp. 443 and 482.
210 “The retinal image is the last effect known of the action of objects on us; what happens beyond the retina we know not; our knowledge of the objective process has at present here its limit.”—Ewald Hering, Beiträge zur Physiologie, 1862, p. 166. That is to say, we have a definite translation of the process in geometric terms as far as the retina, and thence onwards Geometry fails us, and Neurology and Psychology are invoked.
211 Compare Problem II. Chap. IV.
212 “Das Bewusstwerden ist nichts Anderes als ein weiter fortgeschrittenes Erinnern oder Neuwerden des von aussen aufgenommenen Wissens, ein innerliches Wissen dieses Wissens oder ein in sich reflectirtes Wissen.”—Jessen, Versuch einer Wissenschaftlichen Begründung der Psychologie, 1855, p. 477.
213 In common language a stone or a tree is said to be unconscious; but this is an anthropomorphic extension of the term. In strictness we should no more speak of unconsciousness outside the sphere of Sentience than of darkness outside the sphere of Vision.
214 The contraction may be effected in the eye out of the organism. See p. 229. It is then no reflex.
215 Glasgow Medical Journal, 1857, p. 451. See also further on, note to p. 426.
216 Mayer, Die Elementarorganisation des Seelenorgans, p. 12, is the authority for the last statement.
217 Allgemeine Zeitschrift fĂĽr Psychiatrie, Bd. 31, p. 711.
218 Aubert, Grundrüge der physiol. Optik, 1876, p. 633. “The accommodative movement of the eye is to be considered voluntary. It is true we contract the pupil without being conscious of the contraction of muscular fibres, but this holds good for every voluntary movement. When a person raises the tone of his voice he is not conscious that by muscular contraction he makes his chordæ vocales more tense; he attains his object without being aware of the means by which he does so. The same is applicable to accommodation for near objects and to the contraction of the pupil accompanying it. The fact that this last is only an associated movement does not deprive it of its voluntary character, for there is perhaps no single muscle which can contract entirely by itself.” Donders, On the Anomalies of Accommodation, 1864, p. 574. Professor Beer of Bonn has the rare power of contracting or dilating the pupils of his eye at will; here ideas act as motors. When he thinks of a very dark space the pupil dilates, when of a very bright spot the pupil contracts. (Noble, The Human Mind, 1858, p. 124.) I believe this to be only an exaggerated form of the normal tendency. In all of us the mechanism is so disposed that the feelings of dilatation are associated with feelings (and consequently ideas) of darkness; and by this association a reversal of the process obtains, so that the idea of darkness calls up the feeling it symbolizes.
219 Spencer, Principles of Psychology, I. 499.
220 Descartes expressly calls them sensitive machines. He refuses them Thought, but neither “la vie ou le sentiment.” He adds, “Mon opinion n’est pas que les bêtes voient comme nous lorsque nous sentons que nous voyons.”—Œuvres, IV. p. 339. This example is cited by him in proof of human automatism: “Que ce n’est point par l’entremise de notre âme que les yeux se ferment, puisque c’est contre notre volonté, laquelle est sa seule ou du moins sa principale action; mais c’est à cause que la machine de notre corps est tellement composée que le mouvement de cette main vers nos yeux excite un autre mouvement en notre cerveau qui conduit les esprits animaux dans les muscles qui font abaisser les paupières.” All indeed that we assign to Sensibility, he assigns to these hypothetical animal spirits, and thence he concludes, “Qu’il ne reste rien en nous que nous devions attribuer à notre âme sinon nos pensées.”—Les
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