In passing in review the various and complicated movements dependent on, or which are called into activity by, the process of deglutition, or, in other words, the transit of food from the mouth to the stomach, it will be easy to perceive that the limits of a thesis like the present will, of necessity, preclude the possibility of my entering upon a detailed illustration of the individual action of each particular part: indeed, it would involve the consideration of a most numerous and intricate complication of muscles; and, even had I time and space, ability to unravel so tangled a net-work of junctions would, I fear, be wanting; therefore I shall only at

tempt an outline of the process, referring those who may wish to complete the picture to some of the popular physiological works. Deglutition is the act of transferring any substance from the mouth to the stomach; but my remarks now are to be taken as relating to the transmission of food after mastication and insalivation. The former of these operations consists in the mechanical reduction of the food to a proper consistence; the latter, the commingling of it with a liquid called saliva, secreted by glands especially appropriated to that function.

The process of deglutating the mass so prepared may be divided into four distinct periods or actions; the first comprehending its passage over the tongue to the fauces, the second from the fauces into the pharynx, the third from the pharynx into the esophagus, and the fourth from the esophagus into the stomach. The first of these is purely an act of volition, it being accomplished solely in accordance with the will of the animal. The food, when sufficiently masticated, is collected from all parts of the mouth, and placed on the surface of the tongue: the apex or tip of the tongue is now raised against the palate, and by its peculiar movements, aided by the bars (which readily allow the food to pass upwards and backwards, but offer a considerable obstacle to its return towards the lips), the food is conveyed to the summit of the dorsum of the tongue, just about the termination of the bony palate. Here it is the second action commences: this, I should say, is partly voluntary, and partly involuntary; in fact, a mixed action and it must be obvious that a very different arrangement must now be made, in order to propel the palate forwards, there being no hard unyielding substance for the tongue to press against, or bars to prevent its falling down towards the lips. A slight inspection of the diagram (letter a) will shew, much more clearly than mere description can, that the tongue, posterior to that part I have called its summit, forms an inclined plane into the fauces, being roofed over (if I may use the term) by the velum palati. This velum palati is, as I have before said, covered with a large glandular mass: whether the secretion from it be a salivary or a mucous one, I know not; but, be it what it may, the pressure of the pellet squeezes out its contents, and by that means the pellet is rendered smooth, and thus glides down over this inclined plane into the fauces. Co-existent with this gliding down of

the pellet, the larynx is raised or swung up between the os hyoides, and also drawn slightly forward, the tongue at the same time being drawn slightly backward: the epiglottis is now shut down upon the glottal opening (which closure I am inclined to think is accomplished partly by the mutual approach of the larynx towards the tongue and the tongue towards the larynx, and partly by the mechanical pressure of the food against the epiglottis). We have now to see how the pellet is prevented from entering the nostrils, there being a free communication between the nose and the fauces; and here again I must refer you to the sketch. Fig. 8 and 9 are the two muscles I have proposed to call the anterior and posterior constrictors of the fauces, and whose actions I have said I should be able to demonstrate. Their use must now be obvious. When the pellet has reached the bottom of this inclined plane, these muscles, contracting, approximate the sides of the fauces, which their peculiar crucial arrangement, as seen in the sketch, admirably adapts them for effecting in fact, the action of these muscles is precisely analogous to the peculiar species of sphincter muscle found at the cardiac extremity of the stomach.

:

It would be scarcely possible to conceive that these muscles would completely close the orifice as an orbicular muscle would; but this is provided for and accomplished by the elevation of the velum plati, or rather its free edge, which is raised by the contraction of the tensor palati muscles, the singular arrangement of which has already been pointed out; so that by the contraction of these muscles, aided by the velum palati, the pellet of food is effectually and beautifully prevented from entering the nostrils. The only passage now left for this pellet of food is that of the pharynx, the entrance of which is held open by two pairs of muscles already described. (See sketch, fig. 6, 7.) There it is immediately grasped by the anterior constrictor (fig. 1), which muscle by the slightest tactile impression is instantly stimulated to powerful contraction, as indeed are all the muscles strictly belonging to the fauces and pharynx. We cannot will that we would swallow; there must be a something of sufficient substance to stimulate or touch these muscles, or the act of deglutition could not be excited. This brings me to the third action, which must obviously be a purely involuntary one, viz. that act by which the food is conveyed through the pharynx into the esophagus. As soon as the pellet of food has

been grasped by the anterior constrictor muscles, the larynx is drawn downward and backward by the sterno-thyroidei and sternohyoidei muscles, so that the constrictor muscles by that means gain a fixed point to act from; the pellet being gradually propelled from the anterior to the posterior part of the pharynx by the alternate contractions of these constrictor muscles. Having reached the posterior part of the pharynx, it is pushed into, or rather it is seized by, the funnel-like commencement of the œsophagus, which seizure is the beginning of the fourth action, viz. the propulsion of the pellet of food through the œsophagus into the stomach. This is admirably accomplished by the peculiar vermicular motion of this tube, which motion it is well adapted for effecting from the remarkable arrangement of its muscular fibres, the two orders of which, as well as their relative situations with regard to each other, I have endeavoured to point out when speaking of its anatomy. Gravity has nothing whatever to do with the transmission of food through it, as by far the greater quantity is swallowed contrary to gravity when an animal is grazing. These vermicular contractions can only be excited by direct tactile impressions, as the muscles of the pharynx and fauces are excited. Hence it will be seen how essential it is that the sophagus should possess a perfectly independent action.

The act of drinking, or the swallowing of fluids, is accomplished precisely in the same way as that of food or any other solid material after it has reached the summit of the tongue or beginning of the inclined plane; the difference being in the way by which the fluid is brought into the mouth. The animal applies its lips to the surface, say, for instance, of a pond of water; the mouth is then, at the will of the animal, exhausted, or rather a partial vacuum is formed, when the pressure of the atmosphere upon the surface of the fluid forces it up into the mouth, and, having forced it up to the summit of the tongue, the same actions take place which I have endeavoured to describe when speaking of the deglutition of food.

It would have afforded me much pleasure to have gone more minutely than I have done into a subject so replete with interest; but I find I have already exceeded the usual limits of an essay. I trust, however, I have rendered the subject sufficiently plain to

be easily understood. My aim has been to divest it as much as I consistently could of all technicalities, thus rendering it of greater practical utility; yet it was not possible to avoid the introduction of anatomical terms.

TUESDAY, NOVEMBER 26, 1844.

The PRESIDENT, Professor Spooner, took the Chair, and acknowledged his re-election to office.

The following were elected members :—

Mr. N. F. Clarkson, senior veterinary surgeon Hon. E. I. Co.'s Service; Mr. J. Aked, V.S., Bury; and Messrs. L. E. T. Vicary, J. Mannington, C. Hawes, W. Burrowes, J. Rose, R. Skelton, W. Chapman, H. Fishwick, W. Kent, J. Sargisson, W. Phillips, J. Shepperson, and T. Bass, students.

The following works were presented to the Library :

By the Patron-" Gilchrist on the History and Treatment of the Diseases of the Elephant."

By the Treasurer-" Burdon's Farrier," 1837.

By Mr. W. Field-" Posthumous Extracts from the Veterinary Records of the late John Field."

By Mr. J. J. G. Wilkinson (translated by him)—Vol. II. "Swenderborg's Animal Kingdom."

By M. U. Leblanc-“La Clinique Vétérinaire.”

By Mr. G. Gamgee—“ Due Righe sopra un Cervello ossificato in un Animale sano, dal dottore Luigi Patellani."

By Mr. J. S. Gamgee-A translation of the above pamphlet. [This will appear in a subsequent number of the Record and Transactions.]

Mr. Ernes stated that he was commissioned by the Veterinary Society of Brussels to request that an exchange of Journals might