Direct comparison of the preparations of these two anthropoid apes just described with the conditions found in many adult human cæca shows the close correspondence in the arrangement of these folds and of their influence on the configuration of the parts.
Figs. 572 and 573—taken from an adult human subject—show a cæcum and appendix which almost reproduces that of the chimpanzee illustrated in [Figs. 462] and [463] and closely resembles that of the orang.
Fig. 572, giving the ventral view, shows, by the course of the ventral longitudinal muscular band, the turn of the cæcum upwards and to the left. The ventral cæcal artery runs in a fold (1) loaded with epiploic appendages.
The non-vascular intermediate fold (Fig. 573, 2) passes to the root of the appendix, joining the proximal segment of the dorsal vascular fold in which the dorsal branch of the ileo-colic artery runs to the tip of the appendix. The distal two thirds of the appendicular mesentery are free.
3. Gibbon, Hylobates hoolock ([Figs. 455] and [456]).—In the gibbon the folds appear well developed. The intermediate and dorsal vascular folds are quite distinct structures, although fusion ([Fig. 456]) has begun at one point, thus limiting a typical posterior ileo-cæcal fossa.
4. Gorilla, Gorilla savagei ([Fig. 457]).—Finally in the gorilla all three folds appear quite distinct and separate from each other, the dorsal vascular fold being especially well developed.
Unusual and Aberrant Types of Ileo-cæcal Folds and Fossæ.—(A) Ventral cæcal artery larger than the dorsal, supplying the greater part of the cæcum and the appendix.
