• They show us, indeed, on the one hand, that sustained intellectual work is accompanied by a loss of phos phorized substance on the part of the cerebral cell in vibration ; that it uses it up like an ignited pile which is burning away its own essential constituents ;t and that, on the other hand, all moral emotion perceived through the sensorium, all effective participation of this same sensorizinz in an excitation from the external world, becomes at the same time the occasion of a local develop ment of heat.
These facts are to have a direct effect upon our knowledge of the essential conditions of the in tegrity of the cerebral functions, and to formulate absolute hygienic principles with regard to them.
It stands to reason, indeed, that if the cerebral cell expend its reserve material during its diurnal activity, it is absolutely necessary, to enable it to continue alive and in health, that it shall repose and sleep regularly. Sleep is to the brain, what needful repose is to our fatigued limbs, the necessary condition of its health. Every one knows, indeed, how great is the number of individuals who have sown the seeds of a cerebral disease by a prolonged infraction of these simple laws of hygiene, and who through reiterated vigils and exag gerated expenditures of activity, have thus passed the physiological limit of the resources at their disposal, and incurred expenditure above their receipts.
On the other hand this development of heat, which is produced in certain circumscribed localities of the brain when an emotion or sensorial impression is reverberating through the plexuses of the sensorium, further shows us with what circumspection we should manage this kind of excitation in individuals whose brain is in a painful condition, either from a recent congestion, or from for mer congestions grafted one upon another.
We all know from more or less personal experience, that when we have a headache, and our sensorinin is in a state of hypersthesia, the smallest noises, the slightest external incidents, produce in us painful shocks, and that the absolute incapacity for work is most painful.
All dcctors know how often, in persons excited by the occurrence of repeated cerebral congestions, paraly tics, maniacs, and even patients wan certain forms of melancholia, the unexpected calling up of an old emo tion, the sight of a relative, may have a sad effect upon their cerebral condition. We see, indeed, their faces redden and grow pale, and very often the effect of an emotion inopportunely provoked, is but the prelude to the return of more and more serious congestive acci • dents.