Thus, when it is the peripheral regions that cease to be in their normal conditions of receptivity, when the sensorial apparatuses are not adjusted in the required direction—when, for instance, certain sensorial plexuses are struck with ana.-sthesia—the unperceived and un registered excitations from the external world are practically absent as far as the sensorium is concerned.
Thus, physicians are well aware how indifferent all individuals are to oscillations of tempera ture in the atmosphere in contact with their bodies ; how little attention they give to what directly touches them, yet only produces in them a confused impression ; how certain individuals with well-marked myopia have a vague and blinking mode of looking at those things in the surrounding visual field which they do not see, and to which consequently they pay no attention ; how easily the deaf are distracted, only following with much trouble the series of ideas brought before them ; how in a great number of individuals attacked with mental diseases the systematization of certain forms of delirium has no other cause than a sympathetic irritation, or sensitive disturbances radiating from the peripheral regions which alone attract their atten tion. (Phenomena of hypochondria.) We know also, that when these same regions are excited, and have arrived at the pitch of pain, they keep the facilities of attention in the sensorium in a permanent condition of erethism. Every one, indeed, knows how vehement a reaction the gainful spot has upon the sensorium when we suffer in any point whatsoever of our sensitive territory ; how completely it absorbs all our attention ; and how profoundly its painful radiation jars upon our conscious personality, which is forced to pay un broken attention to what is occurring.
In other circumstances it is the central regions that are engaged, and therefore place an obstacle in the way of the regular perfection of the processes of atten tion.
Thus, in idiots and imbeciles, the state of imperfec tion of the nervous system, either of the peripheral or central regions, renders them dull in perceiving,regularly, impressions from without. Their senses are dulled,
their sensibility obtuse, and thus they are capable of but a slight degree of attention. They see badly, hear badly, feel badly, and their sensorium is in consequence in a similar condition of sensitive poverty. Its impressionability for the things of the external world is at a minimum, its sensibility weak, and con sequently it is difficult to provoke the condition of physiological erethism necessary for the absorption of the external impression.
Thus it is that defect of attention is the rule in these special forms of mental degradation, and it is not with out reason that Esquirol has connected the inaptitude of idiots for education with their defect of attention.* In all forms of mental disease the faculty of atten tion becomes gradually weaker, and presents, according to the intensity of the morbid process, different and fatally progressive modifications.
In a general way, in persons with hallucinations, in dividuals attacked with acute or chronic mania, etc. etc., the forces of attention cease to take effect, the pheno mena of the external world no longer produce in the sensorium anything more than an abortive impression. Morbid excitations are developed locally in the very regions of subjectivity, which become erethised of their own accord, and thus virtually become an insurmount able barrier between the individual and the surrounding medium. The patient, thus shut up from external sounds, a stranger to everything that passes around him, lends but an inattentive ear to the things of the external world. He lives, as people say, in himself, upon remembrances of the past, and upon his habitual delirious conceptions. Days pass away, the world goes by, events succeed around him, he no longer pays any attention, and the progressive indifference and invading apathy which manifest themselves in him, attest the gradual exhaustion of the vital forces of his mental activity.*