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real functions; his tongue, his feet, his eyes, his memory, fail him; and at laft, deprived of all power of motion and fenfe, he finks into an inanimate

SLEEP.

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

After fome time the excitability becomes diminished in quantity, being expended by the great activity of the fyftem; and thence when the stimulus of the opium ceases, the fibres will not obey their natural stimuli, and a conSequent torpor enfues, 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 exhaufted fibres takes place, which is fo great, as to occafion a fecond over-exertion on the application

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

But if a fecond dofe 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 ufual dofes, cease to ftupify and intoxicate those who are habituated to their ufe.

But when a ftimulus is repeated at fuch diftant intervals of time, that the natural quantity of excitability becomes completely restored in the acting fibres, it will then act with the fame energy as when first applied. Hence those who have lately accustomed themselves to large dofes 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 dofe as they took at first, otherwife they will experience the inconvenience of an over-dose *.

2. The fibre is faid to be in a state of irreparable exhauftion, when it does not recover its due degree of irẻ RITABILITY, and fails upon the application of the proper ftimuli. All then is languor and debility. The actions within the body are infufficient for the maintenance of life.

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

* A lady labouring under a cancer of her breaft, 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, fhe had taken the whole parcel fhe had got from the apothecary, and therefore fent 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 she should begin with a small dose only; therefore, as fhe had taken 60 grains of the former, fhe would take 20 of the new parcel. But fuch was the effect of intermiffion, that these 20 grains had very nigh killed her. In 10 or 15 minutes fhe was affected with fickness, tremor, giddiness, delirium, and convulfions. Happily for her the fickness proceeded to a vomiting, which threw up part of the powder, or the whole, but notwithstanding this the delirium, and even the convulfions, continued many hours. Vide Cullen's Materia Medica.

7

mospheric

.

mospheric air in the lungs; this, with the addition of fome milk, or mild food, taken into the ftomach, is all the ftimulus 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 fome time after birth with a thick mucus occafioning deafness, and the eyes are fhut against, or turn from, the impreffion of ftrong light. In this ftate, as was before fhewn, 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, fo act upon it, and exhauft it, as to produce almost constant fleep*. From day to day the irritability of the fibre gets diminished, as is known to us by the circumstance of the same stimulants having a leffer 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 juft equilibrium between the powers of the ordinary ftimulants and the irritability in the muscular fibre; yet, at the fame time, as the continued application of the ordinary ftimuli is abfolutely

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

neceffary

neceffary to life and health, fo the daily effects of these is a small degree of exhaustion of irritability, and the state of health and periodical fleep. But again, according to the organization of our bodies, though fleep restores the healthy ftate of irritability in a certain degree, yet it feems never to restore actually the former flate; a small degree of exhauftion of irritability takes place every year. This gradual change, confequently, not only indicates the power of bearing, but also the neceffity of the application of stronger ftimuli, as we advance in life, until, at laft, 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 impreffions neceffary 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 confequence of frequent ine briety, or of daily taking too much vinous spirit without inebriety, consists in the paralysis which usually fucceeds long and violent excitement. Sometimes the ftomach

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