In Figs. 500 and 501, taken from an embryo of 4.9 cm. vertex-coccygeal measure, the final rotation of the caecum from the position occupied in Fig. 498 has occurred and the concavity of the pouch is directed caudad and towards the left. At the same time the escape of the terminal ileal coils from behind the caecum and beginning of the colon has not yet taken place and hence the colon is still kept by these coils from direct opposition to the dorsal prerenal parietal peritoneum. The condition presented by this preparation can be schematically indicated by Figs. 492 and 493. The rotation has carried the beginning of the colon (Fig. 500), with the caecal bud and appendix curved on itself and turning its concavity to the left, into the subhepatic position. The greater part of the small intestinal coils lie now below and to the left of the caecum, but the terminal ileal convolutions (Fig. 500) still occupy a retro-caecal position, separating the pouch and the colon from the dorsal parietal peritoneum. In Fig. 501 the right lateral view of the same embryo is shown with the caecum and colon depressed and turned to the left. The termination of the ileum reaches the ileo-colic junction by passing behind the caecum, and the immediately adjacent ileal coils are still retro-caecal, intervening between the pouch and the dorsal parietal peritoneum. In the next succeeding stage (schema, Fig. 494) these coils of the ileum turn downward and to the left so as to lie below and mesad to the caecum and colon, thus permitting the direct apposition of the large intestine to the parietal prerenal peritoneum. The terminal ileum now passes from below and to the left upwards and to the right to its junction with the colon. This freeing of the dorsal surface of caecum and colon from contact with the coils of the small intestines, and the consequent direct apposition of the same to the dorsal parietal peritoneum influences to a great extent the subsequent arrangement of the parts, because it affords the conditions necessary to the fixation of the colon and mesocolon by adhesion to the parietal peritoneum (cf. p. 81).