496 OF FOOD, AND THE DIGESTIVE PROCESS. 



v 



the sides of the arch to approach each other like a pair of curtains ; so that 

 the passage from the fauces into the posterior nares is nearly closed by them ; 

 and to the cleft between the approximated sides, the uvula is applied like a 

 valve. A sort of inclined plane, directed obliquely downwards and backwards, 

 is thus formed ; and the morsel slides along it into the pharynx, which is 

 brought up to receive it. Some of these acts may be performed voluntarily ; 

 but the combination of the whole is automatic. The third stage of the pro- 

 cess, the propulsion of the food down the oesophagus, then commences. 

 This is accomplished in the upper part by means of the constrictors of the 

 pharynx; and in the lower by the muscular coat of the oesophagus itself. 

 When the morsels are small, and are mixed with much fluid, the undulating 

 movements from above downwards succeed each other very rapidly ; this 

 may be well observed in Horses whilst drinking; large morsels, however, are 

 frequently some time in making their way down. Each portion of food and 

 drink is included in the contractile walls, which are closely applied to it during 

 the whole of its transit. The gurgling sound, which is observed when drink 

 is poured down the throat of a person in articulo mortis, is due to the want 

 of this contraction. The whole of the third stage is completely involuntary. 

 At the point where the oesophagus enters the stomach, the cardiac orifice of 

 the latter, there is a sort of sphincter, which is usually closed. This opens 

 when there is a sufficient pressure on it, made by accumulated food ; and after- 

 wards closes, so as to retain the food in the stomach. The opening of the 

 cardiac is one of the first acts which takes place in vomiting. When the 

 sphincter is paralyzed by division of the pneumogastric nerve, the food regur- 

 gitates into the oesophagus. 



657. Action of the. Stomach. A remarkable opportunity of ascertaining the 

 condition of the Stomach during Digestion, presented itself, some lime since, 

 in a case in which a large fistulous aperture remained after a wound that laid 

 open the cavity, but in which the general health was completely recovered ; 

 so that the process may be considered as having been normally performed.* 

 "The inner coat of the stomach, in its natural and healthy st.ate, is of a light 

 or pale pink colour, varying in its hues, according to its full or empty state. 

 It is of a soft or velvet-like appearance, and is constantly covered with a very 

 thin, transparent, viscid mucus, lining the whole interior of the organ. By 

 applying aliment or other irritants, to the internal coat of the stomach, and 

 observing the effect through a magnifying glass, innumerable lucid points, and 

 very fine nervous or vascular papilla?, can be seen arising from the villous 

 membrane, and protruding through the mucous coat, from which distils a pure, 

 limpid, colourless, slightly viscid fluid. The fluid thus excited is invariably 

 distinctly acid. The mucus of the stomach is less fluid, more viscid or albu- 

 minous, semi-opaque, sometimes a little saltish, and does not possess the slight- 

 est character of acidity. The gastric fluid never appears to be accumulated in 

 the cavity of the stomach while fasting; and is seldom, if ever, discharged 

 from its proper secerning vessels, except when excited by the natural stimulus 

 of aliment, mechanical irritation of tubes, or other excitants. When aliment 

 is received, the juice is given out in exact proportion to its requirements for 

 solution, except when more food has been taken than is necessary for the 

 wants of the system." That the quantity of the Gastric Juice secreted from 



* Sec I!M' case of Alexis St. Martin, \vith tlic observations and experiments of Dr. Ben.il- 

 jnont, repuMi^lied in this country by Dr. A. Combe. [A \er\ extended examination of the 



phenomena of ^a>iiic di^eMioti has been made by Al. Blondloi. The chief subject of ex- 

 periment \va.-a dot:, in v." I lie 1 1 lie maintained, \viihoMi a I led mi: the health, a li Minions opening 

 into the stomach Jin- more than two years. His examinations have furnished many new 

 and important facts, and have continued those of Dr. Beaumont made on Alexis St. Martin 

 in nearly every point. Traite dnalytique dc la Digestion, Paris, 1844. M. C.] 



