Of the SENSIBILITIES governing the actions of the STOMACH.— The examples recently given may introduce us to an acquaintance with those internal sensibilities which excite the actions of parts quite removed from the influence of the will; but the description of the organs themselves may be deemed unnecessary. Let us take the instance of the guard which nature has placed on the lower orifice of the stomach, to check the passage of aliments not easy of digestion, which the appetites of hunger and thirst may have tempted one to swallow. This lower orifice is encircled with a muscular ring, and the ring is in the keeping of a watchful guard. If we are employing the language of metaphor, it is of ancient use; for the Greeks called this orifice pylorus, signifying a porter. And his office is this: when the stomach has received the food, it lies in the left extremity, or is slightly agitated there. When the digestive process is accomplished, the stomach urges the food towards the lower orifice. If the matter be bland and natural, it passes, and no sensation is experienced. But if crude and undigested matter be presented, opposition is offered to its passage; and a contention is begun which happily terminates in the food being thrown again to the left extremity of the stomach, to be submitted to a more perfect operation of the digestive power seated there. It is during this unnatural retrograde movement of the food, that men are made sensible of having a stomach. Yet the sensations, how unpleasant soever, are not to be regarded as a punishment; but rather as a call on reason to aid the instinctive powers, and to guard against disease, by preventing impure matters from being admitted into the portion of the intestinal canal which absorbs, and would thus carry those impurities into the blood to engender disease.

Here, then, is another example of a sensibility bestowed to guard us against external influences, when they threaten destruction to the framework; and to regulate the operations of internal parts too complicated and too remotely situated for the superintendence of reason.

Medical authors, without being empirics, seem occasionally, from the rules they lay down, to calculate on the ignorance of the community. They appear to ignore the sensations expe

*The upper orifice was called by | purveyor, from two words signifythem œsophagus, as if it were the ing, to bring food.

rienced in the stomach during the process of digestion: and yet no harm can be apprehended from giving a man confidence in the warnings which these impart, as to the functions being healthy or disturbed. We have the best proof of what we wish to inculcate in the action of the ruminating stomach. A cow swallows the gross herbage, and fills its large first stomach. When it chews the cud, the stomach, by its action, rolls up the grass into distinct pellets, or balls, with as much regard to its being returned into the mouth, as we do in masticating and rolling the morsel in preparation for swallowing. When the ball is brought into the mouth and chewed, it is again swal lowed; but in descending into the lower part of the gullet, a muscle draws close the aperture by which it had passed into the large stomach in the first instance; it is now ushered into a second stomach, and so successively onwards to that stomach in which the digestion is performed. The curious muscular apparatus by which this is accomplished need not be described; but surely the sensibility which directs it, and which, although independent of the will, is yet so like an operation of reason in its results, presents a subject of just admiration.

The elastic structure of the camel's foot; the provision around its eyes for ridding them of offensive particles; the power of closing its nostrils against the clouds of sand; and its endurance of fatigue-would not enable it to pass the desert, unless there were provisions for the lodgment of water in its stomach, and unless this apparatus were animated by peculiar sensibilities. Accordingly, a muscular apparatus is provided for retaining the water in the cells of its stomach, only permitting it to ooze out according to the necessities of the animal; there is also a muscular band which pulls up the one or the other of the orifices of the different stomachs, to receive the food from the lower end of the gullet, according to its condition, whether to be deposited merely as in a store, or to be submitted to the operation of digestion. The surprising thing in all this is not so much the mechanical provision, as the governing sensibility. What, for example, should, in the first place, impel the grosser food, newly collected, into the first stomach? What, after rumination and mastication in the mouth, should carry that into the third stomach? And why should the water be carried into neither of these, but into the cells of the second stomach?

Yet, after all, this only brings us back to a sense of the operations in our own bodies. The act of swallowing,-the propulsion of the food into the gullet, the temporary closing of the windpipe by the epiglottis, the momentary relaxation of the diaphragm, fibres of which encircle the upper orifice of the stomach at such a time,-is just as surprising. The shutting of the larynx by the epiglottis is never deranged but by the interference of the will. If the individual attempt to speak, that is, to govern the parts by volition, when they should be left to these instinctive actions, or if terror, or some such mental excitement, prevail at the moment of swallowing, then the morsel may stick in the throat.

All this shows how perfect the operations of nature are, and how well it is provided that the vital motions should be withdrawn from the control of reason, and even of volition, and be subjected to a more uniform and certain law. But the point to which we would carry the reader is this,—that the human stomach, though not so complicated in its apparatus of macerating and digesting vats as in some of the lower animals, especially the herbivorous, is possessed of a no less wonderful degree of governing sensibility, which may be trusted to as surely as the precepts of the most skilful physiologist. We are told that we must not drink at meals, lest the fluid interfere with the operation of digestion. Of this there need be no apprehension. The stomach separates, and lets off with the most curious skill, all superfluous fluid through its orifice; while it retains the matter fit for digestion. It retains it in its left extremity, permitting the fluid to pass into the intestines, there to supply the other wants of the system, no less important than digestion. The veterinary professor, Coleman, ascertained that a pail of water passed through the stomach and intestines of a horse at the rate of ten feet in the minute, until it reached the larger bowel. Drinking at a stated period after meals, say an hour, is at variance with both appetite and reason. The digestion is then effectually interfered with; for what was solid has become a fluid (the chyme); this fluid is already in part assimilated; it has undergone the first of those changes which fit it ultimately to be the living blood: and the drink mixing with it must produce disturbance, and interrupt the work of assimilation.

Looking in this manner upon the very extraordinary proper⚫ties of the stomach, we perceive how natural it was for physicians to give a name to the sensibility of which we have been speaking. The Archeus of Van Helmont, the Anima of Stahl, were the terms used to designate this nature, principle, or faculty, subordinate to and distinct from perception; a notion entertained, and more or less distinctly hinted at, by philosophers, from Pythagoras to John Hunter.

We now learn what is meant by organic and by animal sensibility. The first is that condition of the living organ which makes it sensible of an impression, on which it reacts, and performs its functions. It appears from what has preceded, that this sensibility may cause the blowing of a flower or the motion of a heart. The animal sensibility is indeed an improper term, because it would seem to imply that its opposite, organic sensibility, was not also animal; but it means that impression which is referred to the sensorium, where (when action is excited) perception and the effort of the will are intermediate agents between the sensation and the action or motion.

We may sum up the inquiry into sensibility and motion thus:1. The peculiar distinction of a living animal is, that its minute particles are undergoing a continual change or revolution under the influence of life. Philosophers have applied no term to these motions.

2. An organ possessed of an appropriate muscular texture, and of sensibility in accordance with the moving instrument, as the heart or the stomach, has the power of action without reference to the mind. The term automatic, sometimes given to those motions, conveys a wrong idea of the source of motion, as if, instead of being a living power, it were consequent upon some elastic or mechanical property.

3. There are sensibilities bestowed on certain organs, and holding a control over a number of muscles, which combine them in action in a manner greatly resembling the influence of the mind upon the body, yet independent of the mind; as the sensibility which combines the muscles in breathing.

4. In the last instance, a large class of muscles is combined without volition. But the whole animal fabric may be so employed; as in the instinctive operations of animals, where there is an impulse to certain actions not accompanied by intelligence.

5. A motive must exist before there are voluntary actions; and hence philosophers have supposed that there can be nothing but instinctive actions in a new-born child. But we must distinguish here what are perfect at first, from what are at first imperfect and irregular, and become perfect by use and the direction of the will. The act of swallowing is perfect from the beginning. The motions of the legs and arms, and the sounds of the voice, are irregular and weak, and imperfectly directed. It is the latter which improve with the mind. From not knowing the internal structure, and the arrangement of the nerves, philosophers, as Hartley, supposed that an instinctive motion, such as swallowing, may become a voluntary act. Volition in the act of swallowing consists merely in putting the morsel within the instinctive grasp of the fauces, when a series of involuntary actions commences, over which we have no more control in mature age than in the earliest infancy. Swallowing is not a voluntary action; the thrusting of the morsel back with the tongue is like the putting of the cup to the lip. It is the preparation for the act of swallowing that is voluntary: but over the act itself we have no control.

It is an error to suppose that all muscular actions are in the first instance involuntary, and that over some of them we ac quire a voluntary power. A child's face has a great deal of motion in it, very diverting from its resemblance to expression, before there can be any real motive to the action. It will crow, and make strange sounds, before there is an attempt at speech. But this gradual development of intelligence and acquisition of power ought not to be called the will attaining influence over involuntary muscles, since, in fact, the apparatus of nerves and muscles is prepared, and waits for the direction of the mind with so perfect a readiness, as to fall into action and just combination before that condition or affection of the mind which should precede the action takes place. A child smiles before anything incongruous can enter the mind, before even pleasure can be supposed a condition of the mind. Indeed, the smile on an infant's face is first perceived in sleep.

6. All the motions enumerated above are spontaneous motions belonging to the internal economy; but the external relations of the animal, the necessity of escaping from injury or warding off violence, require a sensibility to those outward impressions,

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