CHYMIFICATION. 601 



and Sandras affirm, that after herbivorous animals have been fed on 

 farinaceous substances, more dextrin, grape sugar and lactic acid are 

 detected in the blood of the vena porta than in that of any other blood- 

 vessel. 1 Trommer, also, detected grape sugar in the blood of the portal 

 vein, but not in that of the hepatic vein in animals to which that sub- 

 stance had been given with their food. 2 The bearing of such observa- 

 tions on the production of sugar by the liver will be shown hereafter. 



In conclusion: Let us inquire into the various agencies to which 

 the food is exposed during the progress of chymification. First. It 

 becomes mixed with the secretions, already existing in the stomach, as 

 well as with those excited by its presence. Secondly. It is agitated by 

 the peristaltic motion of the stomach itself, and the movement of the 

 neighbouring organs. Thirdly. It is exposed to a temperature of at 

 least 100 of Fahrenheit, which, during the ingestion of food, does 

 not rise higher: exercise elevates, whilst sleep, or rest, or a recum- 

 bent posture, depresses it. 3 After food has been subjected to these 

 influences, the conversion into chyme commences. This always takes 

 place from the surface towards the centre: the nearer it lies to the 

 surface of the stomach, the more it is acted on; and the part that is in 

 contact with the lining membrane is more digested than any other ; 

 appearing as if corroded by some chemical substance capable of dis- 

 solving it. 



Dr. Wilson Philip 4 asserts, that the new food is never mixed with 

 the old; the former being always found in the centre, surrounded on 

 all sides by the latter. If the old and new be of different kinds, the 

 line of separation between them is so evident, that the former may be 

 completely removed without disturbing the latter; and if they be of 

 different colours, the line of demarcation can frequently be distinctly 

 traced through the parietes of the stomach before they are laid open. 

 Dr. Beaumont, 5 however, affirms, that this statement is not correct; 

 that, in a very short time, the food, already in the stomach, and that 

 subsequently eaten, become commingled. In the subject of his experi- 

 ments, he invariably found that the old and new food, if in the same 

 state of comminution, were readily and speedily combftied. 



The conversion of the food into chyme, it has been conceived, com- 

 mences in the splenic portion, is continued in the body of the viscus, 

 and completed in the pyloric portion. On this point, the observations 

 of Dr. Philip differ somewhat from those of M. Magendie, 6 the former 

 appearing to think, that chymification is chiefly accomplished in the 

 splenic portion and middle of the stomach; whilst the latter affirms, 

 that it is mainly in the pyloric portion that chyme is formed ; the ali- 

 mentary mass appearing to pass into it by little and little, and during 

 its stay there to undergo transformation. He further affirms, that he 

 has frequently seen chymous matter at the surface of the alimentary 



1 Gazette Mdicale de Paris, Jan., 1845. 



2 Kirkes and Paget, Manual of Physiology, Amer. edit., p. 191, Philad., 1849. 



3 Beaumont, On the Gastric Juice, p. 274. 



4 Exper. Inquiry, ch. vii. sect. 1 ; and Treatise on Indigestion, Lond., 1821. 



6 Op. citat., p. 89'. 6 Precis, &c., edit.'cit., ii. 88. 



