moment favor or obstruct particular openings. Paths that have been frequently traversed will of course be more readily traversed again; but this very facility will sometimes be an obstacle, since it will have caused that path to be preoccupied, or have fatigued the organ to which it leads.

199. Since the escape of an excitation must always be along the lines of least resistance, an obvious explanation of the restriction to certain paths has been to assume that some fibres and cells have naturally greater resistance than others. But this explanation is simply a restatement of the fact in other words. What is this greater resistance? Why is it present in one fibre rather than in another? We should first have to settle whether the resistance was in the nervous pathway itself, or in the centre, or in the organ innervated; an excitation might pass along the nervous tract, yet fail to change the state. of the centre, or the organ, sufficiently to produce an appreciable response; and only those parts where an appreciable response was produced would then be considered as having had the pathways of propagation open.

200. When we reflect on the innumerable stimulations to which the organism is subjected from so many various points, and remember further that each stimulation leaves behind it a tremor which does not immediately subside, we shall conceive something of the excessive complexity of the mechanism, and marvel how any order is established in the chaos. What we must firmly establish in our minds is that the mechanism is essentially a fluctuating one, its elements being combined, recombined, and resolved under infinite variations of stimulation. If it were a mechanism of fixed relations, such as we find in machines, or in the "mechanism of the heavens," we might accept the notion of certain organites having greater resistance as a consequence of their structure, just as one mus

cle resists being moved by the impulse which will move another. Nor is it doubtful that such differences exist in nervous organites; but the laws of central excitation are not interpretable by any such hypothesis, since we know that the paths which were closed against an impulse of considerable energy may be all open to an impulse of feebler energy, and that a slight variation in the stimulus will be followed by a wide irradiation. For example, a grain or two of snuff will excite the violent and complex act of sneezing, but the nerves of the nasal cavity may be pinched, cut, or rubbed, without producing any such result. One group of nervous organites will fail to involve the activity of neighboring groups; and the simple movement of a single organ is then all that appreciably follows the stimulation; yet by a slight change in the stimulation, the organites are somewhat differently grouped, and the result is a complex movement of many organs. It is this fluctuation of combination in the organites which renders education and progress possible. Those combinations which have very frequently been repeated acquire at last an automatic certainty.

We are now in a position to examine with more precision the extremely important laws of nervous action which are involved in the phenomena designated by the terms Reflex Action, Automatic Action, and Voluntary Action.

PROBLEM III.

ANIMAL AUTOMATISM.

"L'organisme le plus complexe est un vaste mécanisme qui résulte de l'assemblage de mécanismes secondaires.". - CLAUDE BERNARD.

"Les corps vivants sont machines à l'infini." — LEIBNITZ.

"Noi lamentiamo con Majendie che nel linguaggio fisiologico siensi intruse le preopinioni psicologiche col trascico inevitabile dei vocaboli, ai quali codeste preopinioni si trovano legate. Probabilmente questa fu una delle principali cagioni degli errori e degli equivoci anatomofisiologici, da cui non poterono svincolarsi, a loro insaputa, i cultori sperimentali della scienza, perchè nell' interpretare i fenomeni osservati erano obbligati ad usare linguaggio di una falsa moneta in corso."-LUSSANA e LEMOIGNE, Fisiologia dei Centri Nervosi, 1871, I. 16.

ANIMAL AUTOMATISM.

CHAPTER I.

THE COURSE OF MODERN THOUGHT.

1. MODERN Philosophy has moved along two increasingly divergent lines. One, traversed by Galileo, Descartes, Newton, and Laplace, had for its goal the absolute disengagement of the physical from the mental, i. e. the objective from the subjective aspect of phenomena, so that the physical universe, thus freed from all the complexities of Feeling, might be interpreted in mechanical terms. As a preliminary simplification of the problem this was indispensable; only by it could the First Notion of primitive speculation be replaced by the Theoretic Conception of scientific speculation. The early thinker inevitably invested all external objects with properties and qualities similar to those he assigned to human beings, and their actions he assigned to human motives. Sun, moon, and stars seemed living beings; flames, streams, and winds were supposed to be moved by feelings such as those known to move animals and men. Nor was any other conception then possible: men could only interpret the unknown by the known, and their standard. of all action was necessarily drawn from their own actions. Not having analyzed Volition and Emotion, above

On the distinction between first notions and theoretic conceptions, see Problems of Life and Mind, Vol. II. p. 277..