REMOVAL OF THE INTESTINES. 321 



2. Cut off the next twelve inches of the jejunum ; wash it through 

 with running water from the tap, inflate it with air, and hang it up 

 to dry. 



3. Cut through the ascending colon about six inches above the 

 ileo-colic junction. Wash through the detached portion, consisting 

 of the lower part of the ileum, the csecurn, and a piece of the 

 ascending colon, inflate it, and hang it up to dry. 



4. Remove the pieces of mesentery left on the remaining long piece 

 of the small intestine. Wash the intestine through from end to end 

 by putting one end on the tap and allowing the water to run 

 through freely ; and, finally, treat the remainder of the large intestine 

 in the same way. 



SMALL INTESTINE. 



The JEJUNUM and the ILEUM together measure about twenty feet Jejunum 

 in length, and are connected with the mesentery. There is not any 

 perceptible difference between the termination of the one and the 

 beginning of the other, but two-fifths of the length are assigned to 

 the jejunum, and three-fifths to the ileum. Between the upper and 

 lower extremities, however, a marked difference may be perceived. 

 The upper part of the jejunum^is thicker and more vascular than Characters, 

 the lower end of the ileum ; it is spongy to the feel, owing to its 

 voluminous mucous membrane, and markedly differs from the thin- 

 walled ileum ; the width of the upper part of the jejunum is also 

 greater. 



STRUCTURE. In the small intestine the wall is formed by the structure 

 same number of layers as in the stomach, viz., serous, muscular, 

 fibrous, and mucous. 



Dissection. Open the small pieces of jejunum and ileum by 

 cutting along the mesenteric attachment ; pin them out on cork with 

 the mucous membrane uppermost. Wash them gently with water, 

 and remove all contained matter and adhering mucus, and examine 

 the villi with a hand lens. 



Villi. The mucous membrane will be seen to be thickly studded TheviUi. 

 with small projections, like those on velvet. These bodies exist Their shape, 

 along the whole of the small intestine, and are irregular in form size> 

 (fig. 118), some being triangular, others conical or cylindrical with a 

 large end. Their length is from ^th to ^th of an inch ; and they 

 are best marked where the valvulee conniventes are largest. In the 

 duodenum their number is estimated at 50 to 90 in a square line, and number, 

 but in the lower end of the ileum at only 40 to 70 on the same 

 surface (Krause). 



Dissection. Now turn the pieces of intestine and pin them out 

 on the cork with the serous coat outermost. 



The serous covering is to be torn off for a short distance, to show 

 the muscular coat, but in doing this the external longitudinal fibres 

 will be taken away unless great care is observed. 



The serous coat is closely connected with the subjacent muscular Serous coat 

 layer. To the jejunum and ileum it furnishes a covering, except 



D.A. Y 



