198 PROFESSOR CHRISTOPHER ADDISON. 



The lower layer of the transverse nieso-colon attains the 

 middle line across the lower part of the head of the pancreas 

 3 cm. below E.F. Passing to the left, it bends abruptly 

 upwards towards the anterior border of the pancreas to the upper 

 border of the duodeno-jejunal flexure, where it attains the level 

 of E.F. 2-8 cm. to the left of the middle line. From this point 

 it continues outwards to the left in a low arch with its convexity 

 upwards, until at a point 8'9 cm. from the middle line, '5 cm. 

 below E.F., it definitely bends downwards to become the inner 

 layer of the peritoneum of the splenic flexure and of the descend- 

 ing colon. 



At this place it follows the slight twist downwards that the 

 extremity of the pancreas usually presents, and running along 

 the inner margin of the lower part of the spleen, is directed for 

 2 cm. slightly outwards, until it attains the outer margin of the 

 left kidney. It then continues downwards along the outer 

 margin of the kidney until its lower pole is reached 6 cm. 

 below E.F., where, in common with tlie descending colon at this 

 part, the peritoneum presents a bend inwards for nearly 2 cm. 

 Continuing downwards with an inclination inwards, it passes 

 over the iliac crest at a distance of 7 cm. from the middle line 

 along with the descending colon, until, at a point 4*6 cm. below 

 the iliac crest, or ll cm. below CD., at a distance of 6-6 cm, 

 from the middle line, it forms the commencement of the inner 

 layer of the meso-sigmoid. As a part of the meso-sigmoid it is 

 directed at first downwards and inwards towards the brim of 

 the pelvis, where, at a level of '9 cm. above the anterior superior 

 iliac spine, 5 cm. from the middle line, it bends again upwards 

 passing inwards, towards the angle formed by the psoas muscle 

 and the lumbo-sacral promontory, where, having passed to 

 within 2*5 cm. of the middle line, it bends downwards and 

 inwards into the pelvic cavity, to become eventually the meso- 

 rectum. 



We have traced already the reflection of the peritoneum on 

 to the back of the caecum and the beginning of the ascending 

 colon and thence to the iliac crest. Its reflection above this 

 point on to the outer side of the ascending colon is not of 

 importance in this place. 



