The Gibbons appear to be naturally very gentle, but there is very good evidence that they will bite severely when irritated, a female Hylobates agilis having so severely lacerated one man with her long canines that he died; while she had injured others so much that, by way of precaution, these formidable teeth had been filed down; but if threatened she would still turn on her keeper.  The Gibbons eat insects, but appear generally to avoid animal food.  A Siamang, however, was seen by Mr. Bennett to seize and devour greedily a live lizard.  They commonly drink by dipping their fingers in the liquid and then licking them.  It is asserted that they sleep in a sitting posture.

Duvaucel affirms that he has seen the females carry their young to the water-side and there wash their faces, in spite of resistance and cries.  They are gentle and affectionate in captivity—­full of tricks and pettishness, like spoiled children, and yet not devoid of a certain conscience, as an anecdote, told by Mr. Bennett will show.  It would appear that his Gibbon had a peculiar inclination for disarranging things in the cabin.  Among these articles a piece of soap would especially attract his notice, and for the removal of this he had been once or twice scolded.  “One morning,” says Mr. Bennett, “I was writing, the Ape being present in the cabin, when, casting my eyes toward him, I saw the little fellow taking the soap.  I watched him without him perceiving that I did so:  and he occasionally would cast a furtive glance toward the place where I sat.  I pretended to write; he seeing me busily occupied, took the soap, and moved away with it in his paw.  When he had walked half the length of the cabin, I spoke quietly, without frightening him.  The instant he found I saw him he walked back again and deposited the soap nearly in the same place from whence he had taken it.  There was certainly something more than instinct in that action:  he evidently betrayed a consciousness of having done wrong both by his first and last actions—­and what is reason if that is not an exercise of it?”

The most elaborate account of the natural history of the Orang-Utan extant is that given in the “Verhandelingen over de Natuurlijke Geschiedenis der Nederlandsche overzeeche Bezittingen (1839-45),” by Dr. Salomon Mueller and Dr. Schlegel, and I shall base what I have to say upon this subject almost entirely on their statements, adding here and there particulars of interest from the writings of Brooke, Wallace, and others.

The Orang-Utan would rarely seem to exceed four feet in height, but the body is very bulky, measuring two thirds of the height in circumference.

The Orang-Utan is found only in Sumatra and Borneo, and is common in either of these islands—­in both of which it occurs always in low, flat plains, never in the mountains.  It loves the densest and most sombre of the forests, which extend from the seashore inland, and thus is found only in the eastern half of Sumatra, where alone such forests occur, though, occasionally, it strays over to the western side.