THE LARGE INTESTINE. 1657 



rarely needed for the removal of foreign bodies, as those small enough to pass the 

 pylorus effect, as a rule, only temporary lodgment in the duodenum and usually 

 reach the ileo-caecal region. 



The jejunum may be distinguished from the ileum by its greater width and 

 thickness, its deeper color, and by the presence of the many large folds of the val- 

 vulae conniventes which can be seen in the collapsed and tense gut by transmitted 

 light. By drawing a loop of intestine out of the abdomen so that, with the loop 

 parallel with the long axis of the body, its mesentery is stretched and straightened, 

 it is easy to determine which is the upper end of the loop, and so to follow the gut 

 either towards the duodenum or the caecum, as may be desired. The finger should 

 be passed down to the spine, keeping in close contact with the mesentery ; if it 

 remains on one side until the posterior attachment is reached, it is evident that 

 there is no twist of the loop and that its upper portion is normally the portion 

 nearest the stomach. As loop after loop is examined, if the intestine leads in an 

 upward direction the color becomes paler, and the walls become thicker owing to the 

 valvule conniventes and to the increase in the submucous and muscular coats. 



Other methods of locating with accuracy a given coil of bowel are ( r ) by means 

 of the length of the vasa recta (3-5 cm. in the upper and i cm. or less in the lower 

 portion) ; (2) by the vascular loops from which the vasa recta originate, which are 

 primary in the first four feet of the mesentery. Secondary loops appear as we go 

 farther down, until in the lower third there is a net-work of loops ; (3) by the loops 

 or ' ' lunettes' ' at the intestinal attachment of the mesentery, best visible by trans- 

 mitted light. Below the first eight feet these lunettes disappear (Monks). 



Enterotomy — for temporary relief of obstruction or distention or for the removal 

 of a foreign body — is done at as low a point as circumstances permit, through a 

 transverse incision at the part opposite the mesenteric attachment. 



E^iterostomy — the establishment of a permanent fistula for the purpose, if it is a 

 jejiinostomy, of feeding the patient in cases of obstruction of the alimentary tract 

 above the opening ; or if it is an ileostomy, of relieving fecal accumulation in cases 

 of obstruction at a lower point — is done by suturing the selected knuckle of gut to 

 the parietal peritoneum by a double line of sutures and opening the bowel between 

 them. 



Enterectomy and entero-anastomosis (either lateral or end-to-end) require for 

 their performance, so far as anatomy goes, application of the facts and principles to 

 which reference has already been made. 



THE LARGE INTESTINE. 



The general plan ot the large intestine has already been given (page 16 17). It 

 is easily distinguished from the small intestine, not so much by its greater size as by 

 being sacculated, excepting, perhaps, the sigmoid flexure. 



The length of the large intestine from the root of the appendix to the beginning 

 of the rectum is, according to Treves, about 1.4 m. (4 ft. 8 in.) in man and 5 cm. 

 (2 in.) less in woman. The extremes were 2 m. (6 ft. 6 in.) and i m. (3 ft. 3 in.). 

 E.xcluding the dilated part of the rectum, the capacity decreases from above. Owing 

 both to variation and to occasional cases of extreme contraction as well as of dis- 

 tention, the diameter is very uncertain. It may vary from 7 cm. (2^ in. ) to 3.5 cm. 

 (if in. ) without the more extreme figures implying a pathological condition. 



Structure. — The mucous coat of the large intestine agrees in its essential 

 structure with that of the small gut, consisting of a stroma resembling adenoid tissue, 

 covered by a single layer of columnar epithelium exhibiting a cuticular border. The 

 chief difference, on the other hand, is the absence of villi, in consequence of which 

 the velvety appearance imparted by the latter is not seen in the large intestine. 

 Valvulae conniventes are also wanting, although there are projections into the large 

 gut involving all or a part of the coats internal to the serous tunic. The muscularis 

 mucosae is less regular in its development, being feebly represeftted in the colon and 

 exceptionally thick in the rectum. 



The glands of Lieberkuhn in general resemble those of the small intestine, 

 but are larger (about .45 mm. in length), and form a more regular and less inter- 



