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90. “The man” then does not feel the prick on his leg, but his leg feels it. The man has no consciousness of what takes place outside the sphere of his sensitive mechanism; and the leg is now outside that sphere. Consciousness—as distinguished from Sentience in general—we have seen to be a resultant of the composition of forces co-operating at the moment; the Sensibility of the spinal cord in the regions below the injury cannot now enter into that composition. It is detached from the upper organs. But inasmuch as the organs it innervates are still living and active, the functions of this detached portion are still displayed. We have seen the dog with divided cord capable of Urination, Defecation, Generation, etc.; its hinder legs, though not moving in a consensus with the forelegs, yet moved independently; and all the normal reflexes of the parts followed on stimulations. To say that “the dog” showed no signs of Sensibility when its hinder limbs were irritated, is identifying “the dog” with the anterior half of the organism which was not in connection with the posterior half. It is equally true that the posterior half showed no signs of Sensibility when the anterior was irritated. The two halves were united by the circulation, nutrition, etc., but disunited as to sensation and volition.
91. Do I then suppose the separated half of an animal to feel pain and pleasure, hope and terror? The reader who has attentively followed the exposition will be at no loss to answer. Pain, pleasure, hope, and terror, are special modes of Sensibility, dependent on particular neural combinations. The organs comprised in the anterior half of the animal furnish the main conditions for these special modes, whereas the organs comprised in the posterior half furnish few or none of those—they contain none of the special Senses, and they are without the chief combining centre, the brain. But since we know that a large amount of normal Sensation is wholly without the special characters of pain, pleasure, hope, or terror, we need not hesitate to assign Sensation to the spinal cord because these characters are absent.
92. All I contend for is that the spinal centres have Sensibility of the same order as the cerebral centres; and that in the normal organism this Sensibility enters as a factor into the general Consciousness—no one portion of the nervous system being really independent of all the others, all co-operating in every result. Over and over again I have had to insist that the property of Sensibility is only the general condition of Sensation; and that each particular sensation receives its character from the organs innervated, plus the reaction of the whole organism. Obviously, therefore, the peculiar character of a sensation, or “state of consciousness,” must vary with the variations in either of these factors. To say that every segment of the spinal cord has Sensibility, is not saying that an excitation of that segment will produce a particular sensation of definite character; because for this definite character there is needed the co-operation of all those parts of the mechanism which enter into the complex product.
93. And here attention must be called to a double fallacy pervading the arguments on the other side. It is always assumed that the reactions of an organ, or part of the organism, when separated from the rest, are typical of their reactions when forming constituents of the normal organism. Nothing of the kind. The movement of a muscle or a limb separated from the body may resemble that movement when normally effected—but only as the movements of a mechanical bird resemble those of a living bird: the modes of production are different. So that were we to grant the postulate of the brain being the exclusive seat of sensation, we should still deny that an action which was effected after removal of the brain was typical of the action effected when the brain was present. The leg of Hunter’s patient jerked when the skin was irritated; but this action could not be altogether the same as the similar action in a leg united with the rest of the sensitive mechanism. Nor is this all. The leg may have been insensible, the spinal segment which innervated it may have been wholly without Sensibility, and still we should have to question the logic which extended such an inference to the very different and far more complex actions of decapitated animals. On this ground:—The leg is, by the hypothesis, insensible because cut off from all connection with the sensitive mechanism. But this is not the case with the decapitated animal: there still remain the essential parts of a sensitive mechanism—all the chief organs are still in activity, still manifesting their functions. Decapitation has produced a great disturbance in the mechanism, and has removed an important centre; but nevertheless every impression excites a connected group of centres, and this group responds.
94. In conclusion, unless we adopt the opinion that Sensation—Consciousness—Sensibility, is something not belonging to the physiological properties of the nervous system in a vital organism (the opinion held by spiritualists), there seems no alternative but to adopt the opinion advocated in this volume, namely, that the physiological properties of the nervous system are inseparable from every segment of that system; and the functions are the manifestation of those properties as determined by the special organs with the co-operation of all.
1 Wordsworth.
2 Crystals not only grow by assimilation, but even repair injuries, with a certain superficial resemblance to the repair of animal tissues. Thus, according to the experiments of Jordan cited by Sir James Paget (Lectures on Surgical Pathology, I. 153, and 2d ed. p. 115), an octohedral crystal of alum, if fractured and replaced in a motherlye will in a few days exhibit a complete restoration of the original form. The whole crystal increases, but the increase is greatest on the broken edge, and the octohedral form is completely renewed. (Comp. § 113.)
3 Cited by Drysdale, Life and the Equivalence of Force, Part II. p. 149.
4 Ranke, Die Lebensbedingungen der Nerven, 1868, p. 80.
5 “Il n’y a peut être pas un seul phénomène chimique dans l’organisme qui se fasse par les procédés de la chimie de laboratoire; en particulier il n’y a peut être pas une oxydation qui s’accomplisse par fixation directe d’oxygène.”—Claude Bernard.
6 Dr. Madden, in his essay On the Relation of Therapeutics to Medicine, 1871, p. 5, gives a remarkable illustration of what may be called the frustration of chemical affinity effected by mechanical conditions. “Before calico can be printed, every loose particle of cotton must be removed from the surface in order that the colored inks may not run. This removal is effected by passing the calico over and in contact with a red-hot iron cylinder, and by regulating the rapidity with which the cylinder revolves, the intense heat burns off the loose fibres, yet does no injury to the woven cloth. In other words, the changes in the relation of the high temperature and the cotton are too rapid to admit of the fibre combining with the oxygen. Let the rate of revolution be reduced but very little, and the calico would burst into flames.” Any one who has snuffed a candle with his fingers will understand this. Dr. Madden further instances certain fulminates which can be detonated in contact with gun-cotton without causing it to explode—the extreme rapidity with which the fulminates expand is too great to enable the gun-cotton to adjust its movements to this new motion. Precisely the same kind of thing occurs in organized matter. If the rate of its changes be reduced below a certain point, the ordinary chemical affinities will assert themselves.
7 I am often reminded of the surprising movements of particles of carbonate of lime in water which my friend Professor Preyer showed me during a visit to Bonn. He had removed one of the concretions, usually found in connection with nerves along the spine of old frogs, and crushed it in water; under the microscope the seeming spontaneity and variety of the movements of the particles was such that had we not known their origin we should certainly have attributed them to vitality: no infusoria could have moved with more seeming spontaneity. It is hardly physiological to conclude that because fragments of tissue manifest ambœbiform movements therefore they are alive (Stricker, art. Die Zelle in his Handbuch der Lehre von den Geweben, 1868, p. 7), or that the heart removed from the body is alive because it still beats. Lieberkühn, Ueber Bewegungserschsinungen der Zellen, 1870, pp. 357–359, cites examples of such movements in undeniably dead substances. For Life, we demand not only Movement, but Functional Activity.
8 Telesius, De Natura Rerum, 1586, V. 184. Telesio might have been saved from the mistake had he attended to what Niphus had said on the point in his Expositio subtilissima, 1559, p. 245. Comp. also Philelphus, Epist. Familiarum, 1502, p. 253, verso.
9 The authorities just cited are Aristotle, De Anima, Lib. II. c. I. Kant, Kritik der Urtheilskraft. Müller, Physiology. Beale, Bioplasm, and Introduction to Todd and Bowman’s Anatomy. Schelling, Erster Entwurf, and Transcendent. Idealismus. Bichat, Recherches sur la Vie et la Mort. Stahl, Theoria Vera Medica. Dugès, Physiologie Comparée. Béclard, Anatomie Générale. Lamarck, Philosophie Zoologique. Comte, Cours de Philosophie Positive. Owen’s Hunterian Lectures, 1854. Herbert Spencer, Principles of Biology.
10 Fletcher, as quoted by Drysdale, Life and the Equivalence of Force, Part II. p. 120.
11 Robin et Verdeil, Traité de Chimie Anatomique, 1853.
12 Paget, Lectures on Surgical Pathology, p. 14.
13 Comp. Haeckel, in Siebold und Kölliker’s Zeitschrift, 1865, p. 342, and his Generelle Morphologie, 1866, I, 135, 336.
14 In the Archiv fĂĽr mikros. Anatomie, 1865, p. 211.
15 Here organization is the simplest form of all—molecular organized structure, which in the higher forms becomes tissue structure, and organ structure. The word structure properly means orderly arrangement of different materials; and molecular structure refers to the different proximate principles which constitute the organized substance. Usually, however, the word structureless indicates the absence of visible arrangement of the parts; a cell has structure since it has nucleus and protoplasm.
16 In the cell-theory established by Schleiden and Schwann, in 1838, and which has formed the basis of modern histology, the cell-wall was endowed with an importance which can no longer be upheld now that the existence of independent
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