CHYMIFICATION. 605 



condly. That amylaceous matters are converted into saccharine,' and 

 these last are absorbed; or they undergo a farther change, by which 

 they are partly converted into lactic acid, and partly into oleaginous 

 matter, and are absorbed in one of these states. Thirdly. That the 

 oleaginous principles are either formed into an emulsion or absorbed 

 without alteration ; and Fourthly. That with the exception of certain 

 mineral substances, matters that cannot be reduced to either of these 

 forms are rejected as excrement. 



In proportion as the food is digested, it passes through the pylorus. 

 After the layer, that lies next to the mucous membrane, has experi- 

 enced the requisite change, and is propelled onwards by the muscular 

 action of the organ, the portion lying next to it becomes subjected to 

 the same process. The gastric fluid, at the same time, penetrates, in 

 a greater or less degree, the entire alimentary mass, so that, when the 

 central portion comes in contact with the surface of the stomach, its 

 conversion is already somewhat advanced. The chyme, thus success- 

 ively formed, does not remain in that organ, until the whole alimentary 

 mass has undergone chymification ; but as it is completed, it is trans- 

 mitted, by the peristaltic action, through the pylorus into the duode- 

 num. In the early stages of digestion, the passage of the chyme from 

 the stomach is more slow than in the lateE. At first, it is more mixed 

 with the undigested portions of food, and, as Dr. Beaumont 1 suggests, 

 is probably separated with difficulty by the powers of the stomach. In 

 the more advanced stages, as the whole mass becomes chymified, the 

 process is more rapid, and is accelerated by the peculiar contraction of 

 the stomach, already described. After the expulsion of the last parti- 

 cles of chyme, the organ becomes quiescent, and no more gastric secre- 

 tion takes place, until a fresh supply of food is received, or some me- 

 chanical irritation is produced in its inner coat. 



The time, required for the complete chymification of a meal, is stated 

 by the generality of physiologists to be about four or five hours. In 

 Dr. Beaumont's case, 2 a moderate meal of meat, with bread, &c., was 

 digested in from three hours to three hours and a half. We believe 

 that, in by far the majority of cases, a longer time than this is neces- 

 sary ; and in laborious digestions, the presence of food can be distin- 

 guished by eructations for more than double the time. It is manifest, 

 that no fixed period can be established for the production of this effect. 

 It must vary, according to the digestive capability of the individual ; 

 the state of his general health ; and the relative digestibility of the ali- 

 ments employed ; all which, as we have already seen, admit of great 

 diversity. 



During chymification, only a very small quantity of air is found in 

 the stomach ; sometimes, none. When met with, it is near the cardiac 

 orifice, or at the upper part of the splenic portion. The experiments 

 of M. Magendie, on this point, have been referred to. The small quan- 

 tity of air, discovered in the stomachs of animals, disproves the idea of 

 M. Chaussier, that we swallow a bubble at each effort of deglutition. 

 If so, the stomach ought to be always inflated, especially after eating, 



1 On the Gastric Juice, p. 96. 2 Ibid., p. 275. 



