Travellers and hunters have noticed the rapidity and ease with which the Gorilla moves when off the ground, and when the size and the weight of the animal are considered it becomes evident that not only must it have great muscular power but a stout heart, good circulation, and capital “wind.” It must be remembered also that it is a great eater of vegetable food, and that it has to consume a large quantity to obtain a supply of nourishment: in other words, it has a very capacious stomach, which has to be carried about and kept very well filled. In order to meet these requirements there is a very capacious chest (much more so than in man), which contains the large lungs and heart, and the belly is flaccid and large, so that the stomach need not press upwards and interfere with the breathing, or with the action of the circulation. Man has twelve ribs on either side, but the Gorilla has thirteen, each of which is longer, stouter, and broader than ours, the result being to make the cavity enclosed by them the greater, but apparently less readily influenced by the muscles of respiration. When we breathe deeply and endeavour to inspire more than is usual we employ certain muscles which act on the ribs, enlarging the cavity of the chest, and then diminishing it as the expiration occurs. The larger the spaces between the ribs, and the more elastic the ribs themselves, the greater is their possible amount of movement. In us it is very great in the child, great in man, but much less in old age, when the elasticity of the ribs diminishes. In the Gorilla, the breadth and strength of the ribs keep the cavity of the chest always vast, and certainly from their solidity and from the small space which exists between the successive ribs, great and unusual efforts of respiration are not very possible. So large is the cavity of the chest in the Gorilla, and so capacious are the lungs, that it is possibly not necessary for it to put itself out of breath, and to call extraordinary muscular exertion into play, during its uneventful life. Having thirteen ribs on either side, and each rib being attached to a separate bone of the spine, the Gorilla has therefore one more spine bone (vertebra) than man, and is all the more long-backed. Moreover, the breast-bone, which is on the front of the chest, is broader in the Gorilla than in man, and at least one-third longer, thus adding to the capacity of the cavity of the chest, making it of about 500 cubic inches; that of man being 330 cubic inches. The lungs and heart of the great Ape resemble those of man, and the great arteries are given off from the main blood-vessel in the same manner in both.