With decreased Action of the Sanguiferous System

Ordo II.

Decreased Irritation.

Genus I.

The reader should be here apprized, that the words strength and debility, when applied to animal motions, may properly express the quantity of resistance such motions may overcome; but that, when they are applied to mean the susceptibility or insusceptibility of animal fibres to motion, they become metaphorical terms; as in Sect. XII. 2. 1. and would be better expressed by the words activity and inactivity.

There are three sources of animal inactivity; first, the defect of the natural quantity of stimulus on those fibres, which have been accustomed to perpetual stimulus; as the arterial and secerning systems. When their accustomed stimulus is for a while intermitted, as when snow is applied to the skin of the hands, an accumulation of sensorial power is produced; and then a degree of stimulus, as of heat, somewhat greater than that at present applied, though much less than the natural quantity, excites the vessels of the skin into violent action. We must observe, that a deficiency of stimulus in those fibres, which are not subject to perpetual stimulus, as the locomotive muscles, is not succeeded by accumulation of sensorial power; these therefore are more liable to become permanently inactive after a diminution of stimulus; as in strokes of the palsy, this may be called inactivity from defect of stimulus.

2. A second source of animal inactivity exists, when the sensorial power in any part of the system has been previously exhausted by violent stimuli; as the eyes after long exposure to great light; or the stomach, to repeated spirituous potation; this may be termed inactivity from exhaustion of sensorial power. See Sect. XII. 2. 1.

3. But there is a third source of inactivity owing to the deficient production of sensorial power in the brain; and hence stimuli stronger than natural are required to produce the accustomed motions of the arterial system; in this case there is no accumulation of sensorial power produced; as in the inactivity owing to defect of stimulus; nor any previous exhaustion of it, as in the inactivity owing to excess of stimulus.

This third kind of inactivity causes many of the diseases of this genus; which are therefore in general to be remedied by such medicines as promote a greater production of sensorial power in the brain; as the incitantia, consisting of wine, beer, and opium, in small repeated quantities; and secondly of such as simply stimulate the arterial and glandular system into their natural actions; as small repeated blisters, spices, and essential oils. And lastly the sorbentia, which contribute to supply the more permanent strength of the system, by promoting the absorption of nourishment from the stomach, and intestines; and of the superfluous fluid, which attends the secretions.