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real functions; his tongue, ' his feet, his eyes, his *memory, fail him ; and at last, deprived of all power of motion and sense, he sinks into an inanimate

SLEEP.

If a grain of opium be swallowed by a person unused to such a strong stimulus, all the vascular system in the body acts with greater energy, all the secretions, and the absorption from those secreted fluids, are increased in quantity, and much pleasure is introduced into the fystem, independent of our ordinary train of thinking, which adds an additional stimulus to that already too great.

After some time the excitability becomes diminished in quantity, being expended by the great activity of the system; and thence when the stimulus of the opium ceases, the fibres will not obey their natural stimuli, and a consequent torpor ensues, as is experienced by drunkards, who, on the day after a great excess of spirituous liquor, feel tremor, palpitation of the heart, head-ach, and

general debility. During this torpor (as will be proved when treating of Law III), an accumulation of excitability in the exhausted fibres takes place, which is so great, as to occasion a second over-exertion on the application

even of the ordinary stimuli, and thus an unequal balance of the excitability and of the natural stimuli continues for two or three days, where the stimulus was violent in degree ; and for weeks in some fevers, from the stimulus of contagious matters *.

But if a second dose of opium be exhibited before the fibres have regained their natural quantity of due excitability, its effects will be much less than the former, because the excitability is in part exhausted by the previous excess of exertion. Hence all medicines repeated frequently gradually lose their effect. Thus aloetic purges lose their efficacy by repetition; and opium and tobacco, if not taken beyond their usual doses, cease to stupify and intoxicate those who are habituated to their use.

But when a stimulus is repeated at such distant intere ivals of time, that the natural quantity of excitability becomes completely restored in the acting fibres, it will then act with the same energy as when first applied. Hence those who have lately accustomed themselves to large doses of opium or aloes by beginning with small ones, and gradually increasing them and repeating them frequently; if they intermit the use of it for a few days

Vide Part IV. The Sect. on Fevers,

only,

only, must begin again with as small a dose as they took at first, otherwise they will experience the inconvenience of an over-dose *.

2. The fibre is faid to be in a state of irreparable exhaustion, when it does not recover its due degree of ir: RITABILITY, and fails upon the application of the proper stimuli. All then is languor and debility. The actions within the body are insufficient for the main. tenance of life.

The babe is a compound of matter, so organized as to be capable of being acted upon by various stimuli, necessary to the continuance of life ; and immediately upon its birth the first stimulus it receives is a quantity of at

* A lady labouring under a cancer of her breast, was advised to the use of cicuta (hemlock); and the accordingly got a quantity of it in powder, and weighed out the doses of it for herself. She began with a small dose; and feeling no sensible effects from that, she went on increasing the quantity. By the time she had come to 60 grains, she had taken the whole parcel she had got from the apothecary, and therefore sent to him for a fresh parcel of the powder. She had in the interim been advised, that when she was to pass from one parcel to another the should begin with a small dose only; therefore, as she had taken 60 grains of the former, she would take 20 of the new parcel. But such was the effect of intermifion, that these 20 grains had very nigh killed her. In To or 15 minutes she was affected with fickness, tremor, giddiness, delirium, and convulsions. Happily for her the sickness proceeded to a vomiting, which threw up part of the powder, or the whole, but notwithstanding this the delirium, and even the convulsions, continued many hours. Vide Cullen's Mxteria Medica.

7

mospheric

mospheric air in the lungs; this, with the addition of fome milk, or mild food, taken into the stomach, is all the stimulus it seems capable of bearing, at this period, confiftent with life and health; the external fenfes cannot endure any strong action on them; hence the tympanum, or drum of the ear, is kindly covered for some time after birth with a thick mucus occasioning deafness, and the eyes are shut against, or turn from, the impression of strong light. In this state, as was before shewn, there is the keeneft irritability; the smallest stimulus, even that of the air of a chamber, more efpecially the purer and colder air abroad, and the mildest food, so act upon it, and exhaust it, as to produce almost constant sleep *. From day to day the irritability of the fibre gets diminished, as is known to us by the circumstance of the same stimularits having a lesser effect on the fibre, in proportion as we advance from infancy to puberty, and from puberty to manhood. At this period of life, viz. about 35 years of age, it appears that there exists, as it were, a just equilibrium between the powers of the ordinary stimulants and the irritability in the muscular fibre; yet, at the same time, as the continued application of the ordinary stimuli is absolutely

Vide Law III. On the Accumulation of Irritability; also page 140.

necessary

necessary to life and health, so the daily effects of these is a small degree of exhaustion of irritability, and the state of health and periodical sleep. But again, according to the organization of our bodies, though sleep restores the healthy state of irritability in a certain degree, yet it seems never to restore actually the former ftate ; a small degree of exhaustion of irritability takes place every year. This gradual change, consequently, not only indicates the power of bearing, but also the necessity of the application of stronger stimuli, as we advance in life, until, at last, that state takes place which we call old age, which is little affected by the ordinary, and scarce fensible of the stronger stimuli; and as these gradually cease to make the impressions necessary to the continuance of life, the death of old age must take place; which happens to mankind at different periods of life, earlier if they have given themselves up to pleasure and a variety of exceffes, and later with those who have followed a moderate way of living, and been generally temperate in their excitements.

The state of the frame in consequence of frequent inebriety, or of daily taking too much vinous spirit without inebriety, consists in the paralysis which usually succeeds long and violent excitement. Sometimes the stomach

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