606 DIGESTION. 



which is not the case. MM. Leuret and Lassaigne 1 found the air, ob- 

 tained from the stomach of a dog fed on meat, to consist of carbonic 

 acid, 43 parts ; sulphuretted hydrogen, 2 parts ; oxygen, 4 parts ; 

 nitrogen, 31 parts ; carburetted hydrogen, 20 parts. Whence these 

 gases proceed will be a subject of future inquiry. 



In a robust individual, chymification is effected without conscious- 

 ness of the process. He finds, especially if the stomach be over-dis- 

 tended, that the feeling of fulness and the oppression of respiration, 

 produced by the distension of the organ, gradually disappear. It is 

 not uncommon, however, for slight shivering or chilliness to be felt at 

 this time ; for the sensations, and mental and moral manifestations to 

 be blunted ; and a disposition to sleep to be experienced. " This con- 

 centration of the whole vital activity," according to M. Adelon, 2 " is 

 so natural to the animal economy, that there is always danger in oppos- 

 ing or crossing it by any extraneous or organic influence ; as by bath- 

 ing, the use of medicine, violent exercise, mental emotions, intense 

 intellectual effort, &c." Gentle exercise, however, would seem to favour 

 digestion. Such is the conviction of Dr. Beaumont, 3 from his observa- 

 tions. In the subject of hrs experiment, he found the temperature of 

 the stomach generally raised by it a degree and a half, and chymifica- 

 tion expedited. Where digestion is imperfect, the signs, already men- 

 tioned, will be accompanied by the disengagement of air and conse- 

 quent eructations ; a sense of weight, or heat, or of unusual distension 

 in the epigastric region, &c. ; but these, as well as the developement of 

 sulphuretted hydrogen, discharged by eructation, are the products of 

 ordinary decomposition or fermentation, and appertain to the morbid 

 condition of the function or to indigestion. Yet, as M. Magendie 4 has 

 remarked, it does not seem, that these laborious digestions are much less 

 profitable than others. The fodfl, habitually received into the stomach, 

 contains far more nutritive matter than is necessary to supply the wants 

 of the system; and, in the cases in question, enough chyle is always sepa- 

 rated in the small intestine to supply the losses, and even to add to the 

 bulk of the body. 



It has been already remarked, that the chyme, first formed, does not 

 continue in the stomach until the whole meal has undergone chymifica- 

 tion ; but that, as soon as it has experienced the necessary changes, it 

 passes through the pylorus into the duodenum. It would appear, that 

 the accumulation of chyme in the pyloric portion of the stomach never 

 exceeds four ounces at any one time. M. Magendie states, that, in the 

 numerous experiments, in which he has had an opportunity of noticing 

 it, he uniformly found, when the quantity amounted to about two or three 

 ounces, it was permitted to pass through the pylorus into the duodenum. 

 This passage of the chyme is effected by the peristaltic action. At the 

 commencement of digestion, the duodenum contracts inversely, and the 

 pyloric portion of the stomach, at the same time, drives its contents 

 into the splenic. This movement is, however, soon followed by one in 

 an opposite direction ; and, after a time, the inverted action ceases, 



1 Recherches sur la Digestion, Paris, 1825. 



2 Physiologic de I'Homme, edit, cit., ii. 433. 



3 On the Gastric Juice, p. 93. 4 Precis, &c., ii. 104. 



