CHYMIFICATION. 575 



tine in the direction of the stomach, the pylorus offers no resistance ; 

 suffering it to enter the organ under the slightest pressure; a circum- 

 stance that accounts for the facility with which bile enters the stomach; 

 especially when there exists inverted action of the duodenum. To the 

 pylorus, however, a more active part has been assigned in the passage 

 of the chyme from the stomach into the intestine. "Nothing in the 

 animal economy," says Dr. Southwood Smith, 1 "is more curious and 

 wonderful than the action of that class of organs of which the pylorus 

 affords a remarkable example. If a portion of undigested food present 

 itself at this door of the stomach, it is not only not permitted to pass, 

 but the door is closed against it with additional firmness; or, in other 

 words, the muscular fibres of the pylorus, instead of relaxing, contract 

 with more than ordinary force. In certain cases, where the digestion 

 is morbidly slow, or where very indigestible food has been taken, the 

 mass is carried to the pylorus before it has been duly acted upon by 

 the gastric juice: then, instead of inducing the pylorus to relax, in 

 order to allow of its transmission to the duodenum, it causes it to con- 

 tract with so much violence as to produce pain, while the food, thus re- 

 tained in the stomach longer than natural, disorders the organ: and if 

 digestion cannot ultimately be performed, that disorder goes on increas- 

 ing until vomiting is excited, by which means the load that oppressed 

 it is expelled. The pylorus is a guardian placed between the first and 

 the second stomach, in order to prevent any substance from passing 

 from the former until it is in a condition to be acted upon by the latter; 

 and so faithfully does this guardian perform its office, that it often, as 

 we have seen, forces the stomach to reject the offending matter by 

 vomiting, rather than allow it to pass in an unfit state; whereas, when 

 chyme, duly prepared, presents itself, it readily opens a passage for it 

 into the duodenum." This view of the functions of the pylorus has 

 antiquity in its favour. It is, indeed, as old as the name, which was 

 given to it in consequence of its being believed to be a faithful porter 

 or janitor, (rtva.copo$, "a porter;' 5 ) but it is doubtless largely hypothetical. 

 We constantly see substances traverse the whole extent of the intestinal 

 canal, without having experienced the slightest change in the stomach. 

 Buttons, half-pence, &c., have made their way through, without diffi- 

 culty ; as well as the tubes and globes, employed in the experiments of 

 Spallanzani, Stevens, and others. There are certain parts of fruits, 

 which are never digested, yet the "janitor" is always accommodating. 

 Castor oil is capable of being wholly converted into chyle ; and would 

 be so, if it could be retained in the stomach and small intestines; yet 

 there is no agent, which arrests its onward progress. Still, from these, 

 and other circumstances, M. Broussais 2 has inferred, that there is an 

 internal gastric sense, which exerts an elective agency ; detaining, as a 

 general rule, substances that are nutritive; but suffering others to pass. 

 The presence of food in the stomach after a meal soon excites the 

 organ to action, although no change in the food is perceptible for some 

 time. The mucous membrane becomes more florid, in consequence of 



1 Animal Physiology, Library of Useful Knowledge, p. 41. 



2 Traite de Physiol. appliquee a la Pathologie ; translated by Drs. Bell and La Roche, p. 314, 

 Philad.. 1832. 



