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cardiac orifice, during inspiration, is closed between the pillars of the diaphragm. Again, to object that, according to the theory of M. Magendie, vomiting ought to be a voluntary phenomenon, is a feeble argument; for it is admitted, that the muscles, which, at the time, compress the stomach, act convulsively. If the diaphragm, in paralysis of the bladder, cannot effect the excretion of the urine, it is because that reservoir is not favourably situate as regards the muscle; and, lastly, the arguments deduced from birds, that they are capable of vomiting, although they have no diaphragm, is equally insufficient, for it is not absolutely necessary that it should be a diaphragm, but any muscle that can compress the stomach.

When the Memoir of M. Maingault was presented to the society of the Faculté de Médecine, M. Legallois and Professor Béclard were named reporters. The experiments were repeated before them by M. Maingault; but, instead of appearing contradictory to those of Magendie, these gentlemen declared, that they were not sufficiently multiplied, nor sufficiently various, to lead to any positive conclusion. MM. Legallois and Béclard subsequently repeated and varied them; and instituted others, from which they deduced corollaries, entirely conformable to those of M. Magendie;' and lastly, M. Bégin2 boldly affirms, "without fear of being contradicted by facts, that there is no direct or authentic experiment, that demonstrates the activity of the stomach during vomiting:"-and he adds, "I have repeated the greater part of the experiments of Magendie; he has performed all in presence of a great number of spectators, of whom I was one; and I can say, with the commissioners of the Académie des Sciences, that I have seen, examined, touched, and my conviction is full and entire." Still, many eminent physiologists have adhered to the idea, that the stomach is the main agent in vomiting; and among these was M. Broussais. He manifestly, however, confounded the phenomena of regurgitation with those of vomiting; which, we have endeavoured to show, are distinct. A case of wound of the left hypochondrium with escape of the stomach was described to the Académie Royale de Médecine, by M. Lépine, and reported upon by MM. Lagneau, Gimelle, and Bérard, which confirms the views adopted by M. Magendie. During the whole of the period, that the stomach remained out of the abdominal cavity, there was no apparent contraction of the muscular fibres of the organ, and none of its contents were expelled, although the patient made violent efforts to vomit. As soon, however, as the stomach had been returned into the abdomen, the efforts were followed by the expulsion of its contents. M. Lépine confirms the observations of Magendie in another point. After each act of vomiting, the patient appeared to swallow air. "I observed him," says M. Lépine, "execute repeated

1 Bulletin de la Faculté et de la Société de Méd., 1813, No. x., and Œuvres de Legallois, Paris, 1824.

2 Traité de Thérapeutique, Paris, 1825.

3 Traité de Physiologie, etc., Drs. Bell and La Roche's translation, p. 345, Philad., 1832. 4 Bulletin de l'Académie Royale de Médecine, 1844. See the cases cited in Philad. Med. Examiner, April 20, 1844, p. 92; also a case of Wound of Abdomen, in Amer. Journ. of the Med. Sciences, Oct., 1846, p. 379.

acts of deglutition, each of which was accompanied by a noise, that seemed to be owing to the passing back of air.'

On the whole, we are, perhaps, justified in concluding, that the ancient doctrine regarding vomiting is full of error, and ought to be discarded; that the inverted action of the stomach, although not energetic, is necessary,-that the pressure, exerted on the parietes of the stomach by the diaphragm and abdominal muscles, is a powerful cause, -and that the more or less complete paralysis of the diaphragm, or destruction of the abdominal muscles, renders vomiting more feeble and more slow in manifesting itself. The deep inspiration preceding the act of vomiting, is terminated by the closure of the glottis: after this the diaphragm cannot move without expanding or compressing the air in the lungs. It, consequently, presents a resisting surface, against which the stomach may be pressed by the contracting abdominal muscles. The order of the phenomena seems to be as follows. The brain is affected directly or indirectly by the cause exciting vomiting ;through the brain and medulla, the glottis is closed, and the diaphragm and abdominal muscles are thrown into appropriate contraction, and press upon the stomach; this organ probably contracts from the pylorus towards the cardia; and, by the combination of efforts, the contents are propelled into the oesophagus, and out of the mouth. These efforts are repeated several times in succession, and then cease, -to reappear at times.. Whilst the rejected matters pass through the pharynx and mouth, the glottis closes; the velum palati rises and becomes horizontal as in deglutition; but owing to the convulsive action of the parts, these apertures are less accurately closed, and more or less of the vomited matter passes into the larynx or nasal fossæ. On account of the suspension of respiration impeding the return of blood from the upper parts of the body, and partly owing to the force with which the blood is sent through the arteries, the face is flushed, or livid, the perspiration flows in abundance, and the secretion of tears is largely augmented.

CHAPTER II.

ABSORPTION.

IN the consideration of the preceding functions, we have seen the alimentary matter subjected to various actions and alterations; and at length, in the small intestine, possessed of the necessary physical constitution for the chyle to be separated from it. Into the mode in which this separation, which we shall find is not simply a secerning action, but one of vital elaboration,-is effected, we have now to inquire. It constitutes the function of absorption, and its object is to convey the nutritive fluid, formed from the food, into the current of the circulation. Absorption is not, however, confined to the formation of this fluid. Liquids can pass into the blood directly through the coats of the containing vessel, without having been subjected to any elaboration; and the different constituents of the organs are constantly sub

jected to the absorbing action of cells, by which their decomposition is effected, and their elements conveyed into the blood; whilst antagonizing cells elaborate from the blood, and deposit fresh particles in the place of those that have been removed. These various substances, -bone, muscle, hair, nail, as the case may be,-are never found, in their compound state, in the blood; and the inference, consequently, is that at the very radicles of the absorbents and exhalants, the substance on which absorption or exhalation has to be effected, is reduced to its constituents, and this by an action, to which we know nothing similar in physics or chemistry: hence, it has been inferred, that the operation is one of the acts of vitality.

All the various absorptions may be classed under two heads:-the external and the internal; the former including those that take place on extraneous matters from the surface of the body or its prolongation -the mucous membranes; and the latter, those that are effected internally, on matters proceeding from the body itself, by the removal of parts already deposited. By some physiologists, the action of the air in respiration has been referred to the former of these; and the whole function of absorption has been defined;-the aggregate of actions, by which nutritive substances-external and internal-are converted into fluids, which serve as the basis of arterial blood. The function of respiration will be investigated separately. Our attention will, at present, be directed to the other varieties; and, first of all to that which occurs in the digestive tube.

I. DIGESTIVE ABSORPTION.

The absorption, effected in the organs of digestion, is of two kinds; according as it concerns liquids of a certain degree of tenuity, or solids. The former, it has been remarked, are subjected to no digestive action, but disappear chiefly from the stomach, and in part from the small intestine. The latter undergo conversion, before they are fitted to be taken up from the intestinal canal.

a. Absorption of Chyle or Chylosis.

1. ANATOMY OF THE CHYLIFEROUS APPARATUS.

In the lower animals, absorption is effected over the whole surface of the body, both as regards the materials necessary for nutrition and the supply of air. No distinct organs for the performance of these functions are perceptible. In the upper classes of animals, however, we find an apparatus, manifestly intended for the absorption of chyle, and constituting a vascular communication between the small intestine and left subclavian. Along this channel, the chyle passes, to be emptied

into that venous trunk.

The chyliferous apparatus consists of chyliferous vessels, mesenteric glands, and thoracic duct. The chyliferous vessels or lacteals, arise from the inner surface of the small intestine;-in the villi, which are at the surface of, and between, the valvulæ conniventes. Prof. E. H. Weber1 has, however, seen them distributed in the interspaces between the

1 Müller's Archiv., u. s. w., s. 400, Berlin, 1847.

villi; the lacteals and blood vessels forming a close network; but he could not detect them in the parietes of the follicles of Lieberkühn. Their origin is almost imperceptible; and, accordingly, the nature of of their arrangement has given occasion to much diversity of sentiment amongst

anatomists. Lieberkühn' affirms,

6

[merged small][graphic][subsumed]

Chyliferous Vessels.

that, by the microscope, it may be shown that each villus terminates in an ampullula or oval vesicle, which has its apex perforated by lateral orifices, through which the chyle enters. The doctrine of open mouths of lacteals and lymphatics was embraced by Hewson,2 Sheldon,3 Cruikshank, Hedwig,' and Bleuland, and by some of the anatomists and physiologists of the present day; but, on the other hand, it has been contested by Mascagni, and others; whilst Rudolphi, Meckel, 10 and numerous others" believed, that the lacteals have not free orifices; but that in the villi, in which absorption is effected, a spongy or sort of gelatinous tissue exists, which accomplishes absorption, and, being continuous with the mouths of chyliferous vessels, conveys the product of absorption into them. Bichat conceived them to commence by a kind of sucker or absorbing mouth, the action of which he compared to that of the puncta lachrymalia or of a leech or cupping-glass; and lastly,-from the observation, often made, that different coloured fluids, with which the lymphatics have been injected, have never spread themselves, either into the areolar tissue, or the parenchyma of the viscera,-M. Mojon," of Genoa, affirmed, that lymphatics have no patulous orifice, and that they take

1 Dissert. de Fabric. Villor. Intest. passim. Lugd., Bat., 1745.

2 Experimental Inquiries; edited by Falconer, Lond., 1774, 1777, and 1780, or Hewson's Works, Sydenham Society's edit., p. 181, Lond., 1846.

3 The History of the Absorbent System, &c., p. 1, Lond., 1784.

4 Anatomy of the Absorbing Vessels, 2d edit., Lond., 1790.

5 Disquisit, Ampull. Lieberkühnii, Lips., 1797.

1797.

Exper. Anatom., 1784; and Descript. Vasculor. in Intestinor Tenuium Tunicis, Ultraj.,

7 See Henle, Allgemeine Anatomie, u. s. w. s. 569, Leipz., 1841.

6 Vasorum Lymphaticorum Corporis Humani Historia, &c., Senis, 1787; and Prodromo

d'un Opera sul Sistémo de Vase Linfatice, Siena, 1784.

9 Anatomisch. Physiologisch. Abhandlung., Berlin, 1802.

10 Handbuch, u. s. w. translated by Jourdan and Breschet, p. 179, Paris, 1805.

11 F. Arnold, Lehrbuch der Physiologie des Menschen, Zurich, 1836-7; noticed in Brit.

and For. Med. Rev., Oct., 1839, p. 479.

12 Journal de la Société des Sciences Physiques, &c. Nov., 1833.

their origin from a cellular filament, which progressively becomes a villosity, an areolar spongiole, a capillary, and, at length, a lymphatic

[merged small][graphic][subsumed][ocr errors][subsumed][subsumed][merged small]

A, A. A portion of the jejunum. b, b, b, b. Superficial lacteals. c. c, c. Mesentery. d, d, d. First row of mesenteric glands. e, e, e. Second row. f,f. Receptaculum chyli. g. Thoracic duct. k. Aorta. i, i. Lymphatics.

trunk;--the absorbent action of these vessels being a kind of imbibition. Lastly, Professor Müller1 affirms, that he has never perceived any opening at the extremity of the villi: in his earlier examinations, he was unable to see appearances of foramina on any part of their surface, but he has observed, in portions of the intestines of the sheep and the ox, which had been exposed for some time to the action of water, that over the whole surface of the villi indistinct depressions were scattered, which might be regarded as oblique openings. He adds, however, that he makes this observation with great hesitation and distrust.

Handbuch der Physiologie, u. s. w., and Baly's translation, p. 269, Lond., 1838.

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