STOMACH AND INTESTINE. 



405 



example, absorb the water of these tissues, 

 coagulate their albumen, and thus corrugate 

 and condense their mass. The narrowing 

 which is produced by inflammation or by 

 morbid growths, may be regarded as more 

 mechanical. It results, either from *he ex- 

 sudation or deposit directly engaging more or 

 less of the cavity of the tube ; or what has 

 a similar effect, from its ultimate contraction 

 first reducing the size of the diseased part, 

 and then trenching upon that of the neigh- 

 bouring healthy parietes. Where the deposit 

 of the new substance has been preceded by 

 a loss of the normal tissue, as often occurs 

 in inflammation and ulceration the con- 

 striction which is thus subsequently brought 

 about is of course much more considerable. 



3. To the above causes of constriction in- 

 trinsic to the tube, we may add several which 

 are extrinsic to it. These are chiefly impor- 

 tant, either by the inflammation they excite, 

 or by the obstruction which constriction 

 beyond a certain limit is apt to produce. 

 Hence they will be hereafter alluded to, in 

 connexion with those displacements of the 

 tube, by which obstruction is most frequently 

 brought about. 



Dilatation. An increase in the calibre of 

 the digestive tube may be the result, either of 

 clistention of its cavity, or of relaxation of its 

 walls, or of both of these causes conjointly. 

 Thus that segment of the canal which is im- 

 mediately above an obstruction, is always 

 found in a state of clistention : its dilatation 

 being obviously produced by an onward trans- 

 mission of the intestinal contents, to the point 

 where their progress is arrested. And even 

 in the absence of direct morbid obstruction, 

 constant distention of the tube can to some 

 extent imitate this state. Thus the colon of 

 persons habitually constipated, frequently be- 

 comes enlarged to a vast extent. And the 

 stomach of the rice-eating Hindoo, or the 

 potato-eating Celt, often acquires a similar in- 

 crease of capacity. 



In many of these cases it, is, however, pro- 

 bable, that the passive distention of the organ 

 is assisted by an actual relaxation of its walls. 

 In the enlarged bowels of obese individuals 

 there can be little doubt that this is the case. 

 And most of the diseases at present asso- 

 ciated under the name of ileus exhibit, as 

 one of their characteristic changes, a relaxa- 

 tion of the bowel, which may be distin- 

 guished from the preceding by its rapid occur- 

 rence, its morbid nature, and its usually con- 

 siderable amount. 



Thickness. It is seldom, if ever, that the 

 walls of the intestinal canal are altered in 

 their thickness only. Apart from the obvious 

 physical effects of distention and constriction, 

 by which their tenuity is respectively increased 

 and diminished, the coats of the bowel rarely 

 undergo changes in this respect, without pre- 

 senting some other appearances, such as be- 

 tray a more important lesion. Indeed, the 

 foregoing alterations in calibre are often as- 

 sociated with changes of texture. 



Thus, in persons who have died from slow 



starvation, the intestines become extremely 

 thin, soft, and transparent. A similar change 

 sometimes accompanies that atrophy of the 

 tube, which is produced by tubercular perito- 

 nitis or by diarrhoea, and is attended by an 

 anaemic pallor of the canal. The dilatation 

 caused by obesity is usually associated with 

 an increased thickness of the intestinal pa- 

 rietes; a condition which has been compared 

 to hypertrophy. Here, however, a careful 

 examination will easily show that the real 

 nutrition of the tube has by no means under- 

 gone an increase commensurate with that of 

 its bulk. The bowel is indeed enlarged : but 

 its muscular coat is softer, paler, and weaker ; 

 and its whole appearances are those of a 

 thickening, which is chiefly due to an increased 

 effusion of fluids interstitial to the normal 

 solid structures. 



Situation. Changes in the situation of 

 various parts of the canal are by no means 

 uncommon. We have already alluded to the 

 great freedom of movement which is natural 

 to the small intestine * ; and have specified 

 the various regions of the abdomen which 

 distention of the stomach f or large intes- 

 tine J may cause these segments respectively 

 to occupy. We have also briefly mentioned 

 the more frequent congenital displacements. 

 We have therefore only to enumerate those 

 displacements which are independent of the 

 above causes. 



The abnormal positions of the different 

 parts of the intestinal canal are naturally divi- 

 sible into the extra-abdominal^ and the infra- 

 abdominal; in other words, into those in 

 which they are placed externally to the abdo- 

 minal cavity; and those in which their change 

 ra situation is within the belly, and thus al- 

 lows them still to be bounded by its walls. 



The first of these classes includes the 

 various kinds of hernia: in which an unna- 

 tural deficiency or weakness of some part of 

 the abdominal parietes allows a portion of 

 the canal to be protruded through them ; 

 forming a displacement which, according to 

 the situation of the protrusion through the 

 wall of the belly, is called inguinal, femoral, 

 abdominal, umbilical, or diaphragmatic hernia. 



Amongst the second class of displacements, 

 or those which are included within the pa- 

 rietes of the belly, we may first mention some, 

 which are attended with few, if any, symp- 

 toms during life ; and are, at least in many 

 instances, a mere adaptation of the canal to 

 external pressure. 



Thus the habit of tight-lacing sometimes 

 gives the stomach an hour-glass shape, some- 

 times thrusts down its projecting cardiac 

 pouch, towards the left hypogastric region 

 and the pelvis. In like manner, the bulk of the 

 organ may be forced aside into various un- 

 usual situations by the pressure of any tu- 

 mour in its neighbourhood. Thus, during the 

 latter stages of pregnancy, the uterus so far 

 encroaches upon the stomach, that the latter 

 impedes the descent of the diaphragm, and 



* See p. 340. f See p. 309. J See p. 362. et seq. 



D D 3 



