292. In the earlier part of this work, the structure, position, and functions of this "second stomach" have been fully described, and the practitioner must bear in mind the peculiar circumstances which relate to its anatomy and physiology, in order to understand the nature and extent of those aberrations to which it is liable. The chyme certainly undergoes some change in this organ, independent of that which is produced on it by its admixture with the bile and pancreatic juice, and which would appear to be affected by the agency of its own peculiar secretion: this secretion may become insufficient in quantity to answer its intended purpose, or its quality may be occasionally vitiated; but there exists no direct evidence upon this point, and we can only maintain the probability of such an occurrence on the ground of analogy. I am quite satisfied, that many morbid affections which have been usually attributed to the stomach, ought to be solely referred to the functional aberrations of the duodenum; and when we consider the situation of this intestine, with respect to the colon, and the pressure which it must suffer whenever this latter gut is loaded with faeces; when we reflect upon the elaborate manner in which it is constructed; the connexion of its nerves with other organs; its limited capacity and motion; its tortuous course; the distress which must arise from its distention, and the irritation which, from such a cause, must be immediately propagated through its nerves to very important parts; when we remember that the pancreatic and biliary ducts may be obstructed by its repletion, and the necessary flow of the bile prevented; and lastly, when we consider that the vena cava inferior, may be thus pressed upon, and the circulation of its blood obstructed, - we shall not have much hesitation in admitting that a morbid condition of the duodenum must prove a pregnant source of local as well as of general distress.

It is also necessary to state that, from the confinement which this intestine suffers at its termination within the ring, at the mesentery, the propulsion of its contents is liable to be retarded or obstructed; and, should any hard or indigestible matter have escaped the action of the stomach, it may, by lodging, occasion a temporary stoppage in this part of the canal.

293. The symptoms, which arise from duodenal indigestion, are easily distinguishable from those which depend upon an affection of the stomach. In a casual paroxysm of this kind, the distress is not felt until some time has elapsed after the indigestible meal, and then no oppression is felt at the pit of the stomach, but on the right side, and a puffiness is frequently perceptible in the region occupied by the intestine. In some cases a severe pain is felt in the back, especially in the region of the right kidney; and Dr. Yeates states a symptom, which I have also noticed on such occasions - a faint and fluttering pulse, occasioned by the pressure of the vena cava against the spine by the distended intestine. Where we have reason to suspect that a fit of duodenal indigestion has arisen from some mechanical obstruction, as above explained, an emetic will prove a safer remedy than a purgative; by its action, the offending substance is regurgitated into the stomach, and thus at once eliminated; whereas a purgative may increase the distress, and even produce further mischief. Glysters, however, will be always advisable, in order to remove any pressure which the colon may occasion by its indurated contents.

In cases where no such mechanical obstruction can be supposed to exist, purgatives are to be preferred to emetics.

294. I believe that where indigestion in the stomach has remained for any considerable length of time, the duodenum rarely escapes corresponding mischief; it is difficult to imagine a case in which the fluids of the stomach are constantly in a vitiated, and those of the duodenum in a healthy condition. The very circumstance of half-concocted chyme being repeatedly urged forward into the cavity of the intestine, will be sufficient to derange its functions. When, therefore, we take a general view of the symptoms which mark confirmed digestion, we must take into consideration the effects produced by the derangement of this important organ. In some cases the evidence of such an affection will be more striking than in others, but in most we shall find some proof of its existence.

295. A casual indigestion in the duodenum may be produced by various causes; in addition to those already enumerated as capable of occasioning such an affection in the stomach, we may mention mechanical obstruction, arising from the presence of nuts, cherry-stones, etc.; a vitiated state of the bile, or a temporary suspension of its flow from the liver, by which the chyme will be prevented from undergoing its destined changes, and thus, remaining in the duodenum, may ferment, and distend the intestine with air: accumulations also in the colon, by diminishing the diameter of the duodenum, will necessarily impede its functions.