"The Angola orang (_Simia troglodytes_ Lin.) is the highest animal; it is much more perfect than the orang of the Indies (_Simia satyrus_ Lin.), which is called the orang-outang, and, nevertheless, as regards their structure they are both very inferior to man in bodily faculties and intelligence. These animals often stand erect; but this attitude is not habitual, their organization not having been sufficiently modified, so that standing still (_station_) is painful for them. "It is known, from the accounts of travellers, especially in regard to the orang of the Indies, that when immediate danger obliges it to fly, it immediately falls on all fours. This betrays, they tell us, the true origin of this animal, since it is obliged to abandon the alien unaccustomed partially erect attitude which is thrust upon it. "Without doubt this attitude is foreign to it, since in its change of locality it makes less use of it, which shows that its organization is less adapted to it; but though it has become easier for man to stand up straight, is the erect posture wholly natural to him? "Although man, who, by his habits, maintained in the individuals of his species during a great series of generations, can stand erect only while changing from one place to another, this attitude is not less in his case a condition of fatigue, during which he is able to maintain himself in an upright position only during a limited time and with the aid of the contraction of several of his muscles. "If the vertebral column of the human body should form the axis of this body, and sustain the head in equilibrium, as also the other parts, the man standing would be in a state of rest. But who does not know that this is not so; that the head is not articulated at its centre of gravity; that the chest and stomach, as also the viscera which these cavities contain, weigh heavily almost entirely on the anterior part of the vertebral column; that the latter rests on an oblique base, etc.? Also, as M. Richerand observes, there is needed in standing a force active and watching without ceasing to prevent the body from falling over, the weight and disposition of parts tending to make the body fall forward.