Inversely, bitter substances, which cause the nerves of taste to shrink, produce in the sensorium a disagreeable reverberation, and inevitably become, under the designa tion of bad substances, the expression of a painful im pression in opposition to the last, and equivalent to that of pain in the purely sensitive order of phenomena.
This specific notion is thus susceptible of being gene ralized, of becoming subjective, and of being applied to the appreciation of purely moral actions, which we declare evil, tainted with wickedness, because they have, without our knowledge, developed in the sensorium a painful im pression, equivalent to that produced by a disagreeable gustatory impression.
3. Gustatory impressions, though incapable of causing great shocks in the emotional regions of our personality, are, like their companions, olfactory impressions, capable of radiating into the different regions of the vegetative sphere; they are both of them fundamental excitations of this special division of cerebral life.
Thus it is they which directly regulate the fictions of the stomach, and through these the life of the organism. Every one knows what a state of erethism is produced in the gastric mucous membrane by sapid, appetizing substances, and what dulness of appetite is produced by insipid ones ; the good appetite produced by the former having a direct influence upon the harmony of the psychic and intellectual activity.
Former gustatory excitations, preserved in the sensorium in the form of persistent reminiscences, are on this account easily evoked, and may be compared with recent ones. They are likewise capable of awaking old memories, contemporaneous with the moments in which they have been deposited in the sensorium, and of reviving past emotions and the old associations of ideas that have accompanied their genesis. Thus the taste of food, wine, or a liqueur, recalls to us such or such a period of our youth, such or such an episode of our life, such or such an incident in our travels. Thus gustative impressions, like all theta fellows, live with the same life that these do, and participate in the same processes of cerebral activity. United to their partners, olfactory impressions, they have a truly specific and penetrating radiation, which extends at once into the domain of intellectual activity and that of purely vegetative life. They thus become
the occasion of a series of memories and comparisons, and of the different gastronomic judgments that we form respecting the degree of sapidness of food, the pre-eminence of certain vintages, and the rules respect ing alimentary hygiene. They become, when intel ligently directed, the occasion of a series of particular satisfactions which are associated with all others, and, as Brillat-Savarin has so well expressed it, outlive all the rest to console us for their loss.
Evolution of Genital Impressions.—Genital excitations, as regards their genesis, their passage through the nervous system, and their diffusion in the sensorinm, present the most remarkable analogies to gustatory impressions, of which they are to some extent a copy.
Like these, they have no nerves of special sensation ; like these they are conducted into the central regions by means of radicle-filaments which are there dispersed according to the special mode of distribution of the posterior roots of general sensibility ;* and like these they are distributed to the substance of the central grey matter of the optic thalamus, and then to the plexuses of the sensorium. It is, however, as yet impossible to determine precisely either the special nucleus reserved for them in the optic thalamus, or the territory where their dissemination among the plexuses of the sensoriunz is effected.
Finally, like gustatory impressions, they are inter mittent and subordinated to the chance arrival of the causes that determine them ; and, as the last point of analogy, if they are as fugitive they compensate for this by their vividness, their intensity, their suddenness ; by the profound manner in which they affect the senso rium, and by the ephemeral character of their mani festations.
Collected principally on the surface of the plexuses of the genital organs which are so rich in erectile genital excitations present at the moment of their genesis (in much ampler proportions) that special phase of erethism common to all their fellow excita tions, when the sensorial impression radiating from the external world is reverberated in the sensitive plexuses and becomes incarnate in the organism.