PHENOMENA OF VEGETATIVE LIFE.
IN the first series of facts, when the excitations derived from the external world are not directly reflected out wards—when, under the influence of one cause or another, the primary impression remains confined within our own organism, it dies away there, and the reverberation which results extends to a greater or lesser distance. The nervous discharge of the process, arrested in its course, reacts upon one region or another of vegetative life, and this depends upon the closeness of the sympathetic links uniting each of these with the sensorium.
We have shown, on the other hand, that by reason of these connections; there exist, as it were, incessantly permeable natural channels, by ;which the impressions of the sensorium may at any moment become associated with the phenomena of vegetative life, and reverberate throughout the whole extent of the life of the viscera.
The result of this arrangement is that every external excitation arriving in the sensorium is sympathetically felt in the different centres of visceral life, and that the slightest excitations that wrinkle the surface of its plexuses, as well as the shocks that overwhelm it, are sympathetically propagated into such or such a depart ment of organic life ; now here and now there, centri fugal currents arise instantaneously, and carry to a distance without our knowledge or voluntary participa tion, prolonged reverberations of the oscillations of the psycho-intellectual sphere.
We all know what an effect painful emotions have upon the phenomena of the circulation ; how the heart palpitates without our knowledge when our emotions are at work ; how apt this latent over-excitement is to fatigue the vital energy, and what a serious, and long ago recognized influence mental causes have as regards the genesis of its organic lesions ; how susceptible the vaso motor innervation is of becoming associated with our emotions in a similar manner ; since instantaneous paralysis of the capillaries, on the one hand, is apt to determine those sudden blushes which by showing them selves upon our faces reveal so well, in spite of us, the secrets of our agitated sensibility ; while, on the other hand, their spasmodic contraction excites those instantaneous pallors which as directly reflect the per turbations that traverse our sensorium.
We all know, moreover, how directly the digestive organs are associated with the impressions of this same sensorium. The stomach in particular is intimately
connected with the phenomena of cerebral activity. Like the heart, it every instant experiences the return shock of our emotions, and like it, becomes the bearer of the sins of our general sensibility. Every one knows that digestion is disturbed by mental emotions ; that vomiting frequently accompanies cerebral disease ; and that in certain localized pains of the sensorium (hemicrania), when too strong external excitation evokes its sensibility, the discharge of the sensorium in erethism takes effect upon the stomach, which to some extent serves as a gate of exit for the nervous over excitement reflected towards the organs of vegetative We all know, further, how intimate is the association between the respiratory organs and our natural emotions. Sighs, spasms, anxieties, the involuntary laugh which sometimes bursts out in so unexpected a manner at the sight of a person who laughs, and the frown which shows itself under similar circumstances, are also co-ordinated external revelations that follow upon an incident exci tation carried into the sensorium, and reverberated to wards the organs whose business it is to carry it off externally.
More than this—and this also is a phenomenon known to us all—in certain circumstances our muscles, which are usually such faithful interpreters of our wills, escape from the regular stimulation of the conscious personality, and then, under the influence of powerful emotions, become subject to invincible excitations radiated from the sensorium, and act like treacherous servants, only in obedience to the instructions of an irregular power, and manifest, without our consent, the different states through which our inner sensibility is passing. It is by reason of this substitution that our gestures, our movements, our attitudes, our physiognomy become, without our knowledge, living expressions of the different states of our sensibility, and in a manner apparent phenomena by which the phase of erethism of certain regions of the sensorium is externally dis charged. In these cases our muscles of expression are grouped aucl harmonized in a co-ordinated manner, so automatically and so unconsciously that we see, for instance, those of the iris dilate and contract alternately, and express by their play, as automatic as unconscious, the different modes of sensibility of the retina which it is their business to protect.