consciousness of ours, prohibits an immoderate effusion, yet ascertains the needful supply.

Sufficiently charged with this adventitious fluid, the nutritive mass pursues its way through the intestines; whose wonderful meanders, are incomparably more curious, than the mazes of the Dædalean labyrinth. They are actuated with a worm-like or undulatory motion; which protrudes the received aliment, and forces its fine milky particles into the lacteal vessels. These are a series of the most delicate strainers; ranged, in countless multitudes, all along the sides of the winding passage. Each so nicely framed, as to admit the nutrimental balmy juices, and reject the gross excrementitious dregs. Had the intestines been straight and short, the food might have gone through them without resigning a sufficient quantity of its nourishing particles; therefore, this grandest of all the vital ducts is artfully convolved, and greatly extended, to afford nature an opportunity of sifting more thoroughly what ever passes, and of detaining whatever may serve her purposes. Lest such lengths of entrails should be entangled among themselves or be cumbrous to the wearer, they are packed into the neatest folds, and lie within a narrow compass. They are at least six times longer than the body which contains them; yet are they lodged, not crowded, in a part, not in the whole region, of the lower belly; and amidst this small space have sufficient room to execute the nicest and most important functions. Though the alimentary substance can never mistake its way, yet it may, through some accidental impediment, attempt to return backward: in this case a valve intervenes, and renders what would be extremely pernicious almost always impracticable. As the whole proceeds in this serpentine course, it is perpetually sending off detachments of nutritious juices; in consequence of which it would lose its soft temperature, might become rugged and

Styled vermicular or peristaltic.

+ According to this calculation, they must measure, in a pretty tall man, more than thirty-six feet. The substance of the bowels, though thin to a delicacy, is strong to a wonder. The skin of an ox gut, I am told, will endure the blows of a goldbeater's hammer for many months, nay for several years.

pain the tender parts, perhaps be hindered from sliding on to its final exit. To prevent such an obstruction, glands are posted in proper places, and discharge a lubricating fluid, which aids the progress of the mass and renews the secretion of the chyle; till all that remains of the one is clean drawn off, and the other But here you must excuse me; and for my neglect of farther particularity, your author shall make an apo logy: Quemadmodum autem reliquiæ cibi depel. lantur, tum astringentibus se intestinis, tum relaxantibus, haud sane difficile dictu est: sed tamen prætereundum est, ne quid habeat injucunditatis oratio.'+

The chyle, drawn off by all the secretory orifices, is carried along millions of the finest ducts, and lodged in several commodious cells: as a traveller, by baiting upon the road, and taking proper refreshment, is better qualified to pursue his journey, so the chyle, diverting to those little inns, is mixed with a thin, diluting, wa tery substance, which renders it more apt to flow, and more fit for use: from hence it is conveyed to one common receptacle, and mounts through a. perpendicular tube. When provision or ammunition is transmitted

In the bowels which lie nearest the stomach, these glands are smaller or fewer, because in those parts, the aliment is copiously furnished with moisture; whereas, in the bowels which are more remote from the stomach, and receive the food drained of a considerable quantity of its chyle, the lubricating glands are either multiplied or enlarged. A most admirable provision! Apparently diversified according to the several changes of the aliment; yet exactly adapted to the exigencies of the animal.

+ Cicero De Nat. Deor. As Theron avoids meddling with a subject which is become useless and putrescent, I think myself obliged to imitate his delicacy; only that I would add one remark in the notes, and shall beg leave to express it in Greek: that if it should prove in any degree disgustful, it may have at least the negative merit not to offend many readers. Erre de τα αποχωρουντα δυσχερη, απεστρεψε τους του των οχετους η φυσίς, και απην εγκεν η δυνατον προσωτατω απο των artndewv. Socrat. Memorab.

Fine indeed! since their orifices, through which they admit the chyle, are not discoverable even by the very best microscopes. To this prodigiously nice constructure it is owing, that nothing enters the substance of the blood but what is smaller than the smallest arteries in the system; and thereby fitted to pass through the finest capillary vessels without causing any obstruction.

The glands of the mesentery.

The receptaculum chyli; a reservatory, placed near the left kidney.

to an army, it generally passes under an escort of able troops: as this is the immediate support and principal nourishment of the whole system, its conveyance is guarded and ascertained with peculiar caution. The perpendicular tube not having sufficient force of its own, is laid contiguous to the great artery, whose strong pulsation drives on the creeping fluid, enables it to overcome the steep ascent, and unload its precious treasure at the very door of the heart. Here it enters the trunk of a large vein, most conveniently opened for its reception; it enters in a slanting or oblique direction. By this method of approach it avoids thwarting, and coincides with the purple stream; which, instead of obstructing its admission, expedites its passage; and instead of being a bar to exclude it, becomes a vehicle to waft it. Its entrance is farther secured by a valve, admirably constructed and most happily situate, which shuts the aperture against the refluent blood, in case it should offer to obtrude itself, but opens a free, safe, and easy avenue to introduce this milk, this manna of nature.

The blood, through every stage of its ample circuit, having sustained great expenses, being laid under contribution by every gland in the whole system, and hav ing supplied myriads of the capillary vessels with matter for insensible perspiration, must be very much impoverished, but is most opportunely recruited by this accession of chyle; yet though recruited, it is not refined. In its present crude state it is absolutely unqualified to perform the vital tour, or carry on the animal functions; therefore, by a grand apparatus of muscular fibres, it is wafted into the lungs, and pours a thousand thousand rills into either lobe. In the cells, the spongy cells of this amazing laboratory, it imbibes the influences of the external air, its heterogeneous parts are thoroughly incorporated, and its whole substance is made cool, smooth, and florid: thus improved, thus exalted, it is transmitted to the left ventricle of the heart, a strong, active, indefatigable muscle, placed in the very centre

Indefatigable. This is a very distinguishing and no less amazing property of the heart. The large muscles of the arm, or the much larger of the thigh, are soon wearied; a day's la bour, or a day's journey, will exhaust their strength; but the muscle which constitutes the heart, works through whole weeks, VOL. I.

of the system. Impelled by this beating engine, part shoots upward, and sweeps, with a bounding impetus, into the head; there it impregnates the prolific fields of the brain, and forms those subtil spirituous dews* which impart sense to every nerve, and communicate motion to every limb: part flows downward, rolls the reeking current through all the lower quarters, and dispenses the nutrimental stores even to the meanest member and the minutest vessel.

Observe how the stately Thames and the rapid Rhine refresh the forests and the groves, water the towns which crowd their banks, and make the meadows they intersect laugh and sing. So, only with an incompar ably richer fluid, and with infinitely more numerous streams, this human river laves the several regions of the body, transfusing vigour, and propagating health, through the whole.

But how shall a stream, divided into myriads of channels, and pervading innumerable tracts, how shall this be brought back again to its source? Should any portion, like your lake-waters after a land-flood, deviate from their course, or be unable to return, putrefaction would take place, a nuisance would arise, death might ensue; therefore the all-wise Creator has connected the extremity of the arteries with the beginning of the veins, so that the same force which darts the crimson wave through the former, drives it through he latter; thus it is reconducted, without the least exravasation, to the great salient cistern:† there played whole months, whole years, and never becomes weary, is equally a stranger to intermission and fatigue.

These are what we call the animal spirits; and it is generally supposed that sensation is caused by the undulatory motion of this nervous fluid; though some imagine it is performed by the vibratory motion of the nerves themselves: others think that neither of these opinions will comport with the texture of those fine tubes, or with the nature of the fluid they contain. It is, I believe, one of those mysteries in the material world which may reconcile thinking and unprejudiced minds to the mysteries of the Christian revelation. Why should any one wonder to find some doctrines in the Bible that surpass the reach of human understanding, when there are so many operations in the body confessedly and absolutely inexplicable by the most acute ana

tomist?

+ Solomon makes use of this similitude,' Or ever the pitcher be broken at the fountain, or the wheel broken at the cistern.' The two ventricles of the heart, replenished with blood, are fitly represented by a cistern, and the contractile force of their fibres

off afresh, it renews and perpetuates the vital functions.

Where two opposite currents would be in danger of clashing, a fibrous excrescence interposes, which, like a projecting pier, breaks the stroke of each, and throws both into their proper receptacle. When the wafture is to be speedy, the channels either forbear to wind in their course,+ or to lessen in their dimensions. When the progress is to be retarded, the tubes are twined into various convolutions, or their diameter is contracted into a narrower size. Modelled by these judicious rules, guarded by these wise precautions, the living flood never discontinues its interchangeable tide; but night and day, whether we sleep or wake, still perseveres to sally briskly through the arteries, and return softly through the veins.

Such astonishing expedients are used to elaborate the chyle, to blend it with the blood, and to distribute both through the body! by means of which the animal constitution is maintained. In youth, its bulk is increased; in age, its decays are repaired, and it is kept in tenantable condition for the soul during the space of seventy or eighty years.

These are a few, and but a very few instances of that contrivance, regularity, and beauty, which are observ. able in the human frame. Attentive inquirers discover deeper footsteps of design, and more refined strokes of skill; discover them not only in the grand and most distinguished parts, but in every limb and in every organ; I may venture to add, in every fibre that is extended, and in every globule that flows.

acts like the water-wheel in hydraulics. The pitcher, which receives the water at the spring-head, and conveys it away for the owner's service, may probably signify the aorta and the pulmonary artery, whose functions correspond with the uses of such a vessel. Eccles. xii. 6.

In the point where the streams from the vena cava and vena ascendens meet.

In the great artery that descends to the feet.

In every interval between all the ramifications.

In the vessels which carry the blood to the brain, which form the viscous secretions, and indeed which constitute all the glands.

The extreme minuteness of the globules which form the red part of our blood, is one exemplification of this remark; if, as Mr. Lewenhoeck computes, every globule be 125,000 times smaller than the smallest grain of sand.