340 



TEXT-BOOK OF EMBRYOLOGY. 



cavity, ventral to the duodenum, forming the transverse colon. It then de- 

 scends on the left side as the descending colon which passes over into the sigmoid 

 colon (Fig. 337). The transverse, the descending and the sigmoid portions of 

 the colon are recognizable in the third month. Up to the time of birth the 

 sigmoid portion is disproportionately long; after birth the other portions 



FIG. 304. Drawing from a reconstruction of a human embryo of 24 mm. Matt. 

 The intestinal coils lie for the most part in the umbilical ccelom. C, caecum; K, kidney; L, liver. 

 S, stomach; S. C., suprarenal gland; W, mesonephros; 12, twelfth thoracic nerve; 5, fifth 

 lumbar nerve. 



grow relatively faster. After the fourth month the portion to which the caecum 

 is attached grows downward in the right side of the abdominal cavity, thus form- 

 ing the ascending colon (Fig. 342). 



The caecum, which appears in very early stages as an evagination at the 

 junction of the small and large intestines, for a time continues to increase uni- 

 formly in size. Then the proximal end increases more rapidly than the distal, 

 and forms the caecum of adult anatomy. The distal end, failing to keep pace 



