18 TEXT-BOOK OF ZOOLOGY 



them, or hold their hands over their head to ward off the rain from 

 their body. 



2. The Orang-Utan is a thorough adept in the art of climbing. 

 According to one of its most careful observers, it moves through the 

 densest forests with the same ease "as the Indian over the steppes or 

 the Arab through the desert." (What renders the animal capable of 

 performing these feats ?) 



(a) The hands are very similar to those of man, but the thumb is 

 shorter and the fingers much longer. Whereas the human hand is an 

 almost perfect instrument for grasping (give proofs of this statement), 

 that of the Orang-Utan is, in accordance with the arboreal life of the 

 animal, specially adapted for climbing from tree to tree, the four fingers 

 serving as hooks in this operation. By reason of their length the animal 

 is able to obtain a safe and sure hold of branches of even more than 

 usual thickness. 



(b) The feet also are constructed on the plan of the hand; i.e., the large 

 toe is opposable to the other toes, just as the thumb is to the other fingers. 

 The large toe is very strong, and can be widely extended (like the thumb 

 in the human hand), and the soles of the feet are turned, not downwards 

 as in man, but obliquely inwards. Consequently, in climbing the animal 

 is able to grasp or embrace stems and branches with great surety, and 

 can thus obtain a firm hold. These hand-like feet are of the greatest 

 importance to the animal. For after having obtained a firm footing by 

 their help, it has its hands free for the most varied kinds of activities, 

 the seizing of food, care of its young, etc. It is, in the same manner, 

 enabled to pluck leaves or fruit from branches which would not bear its 

 weight. 



(c) The arms are of great length, and by reason of the short legs, 

 which, moreover, are never fully extended at the knee-joint, almost reach 

 down to the feet. This great length of arm enables the creature to grasp 

 branches at a great distance, to pluck fruit from the swaying summits of 

 the trees and the ends of branches, and to lay hold of the boughs of 

 neighbouring trees for the purpose of swinging itself on to them. If one 

 branch is not found strong enough to bear its weight, the animal with its 

 gigantic hands seizes hold of a whole cluster. The great length of the 

 arm, further, enables the animal to walk down branches placed in a 

 slanting direction. If its arms were not longer than those of man, it 

 would, in consequence of the forward displacement of the centre of 

 gravity, be exposed to the danger of falling (like a hare running 

 downhill) . 



(d) Motion from one branch or one tree to another requires much 

 greater strength than any movement on a level surface. Hence the 



