1064 Influence of circumstances on the Actions of Animals. 
pose that this animal has received from nature the organization 
which it possesses, we must believe that this organization has 
forced it to adopt the habits and miserable state in which it is 
found. I hesitate to believe thus, for I am convinced that the 
habits which the individuals of the race of the Ai have been forced 
to contract originally, have necessarily brought their organization 
to its present state. That since continual danger has formerly 
made the individuals of this species take refuge in trees, to live 
there habitually, and to sustain themselves there on their leaves, it 
is evident that they must be deprived of a multitude of movements 
which animals who live on the ground are in the habit of making. 
All the wants of the Ai have been then reduced to the hanging on 
the branches, to creeping, or to crawling to get the leaves, and after- 
wards to resting on the tree in a state of inactivity, and always to 
avoid falling to the earth. Besides, this kind of inactivity would 
be constantly encouraged by the heat of the climate; for, with ani- 
mals of warm blood, heat predisposes them more to rest than to 
movement. Now, the individuals of the race of the Ai having for 
a long time preserved the habit of resting on trees, and of making 
only slow and little varied movements which suffice for their wants, 
their organization, little by little, would be brought into harmony 
with their new habits, and this would be the result: 1st.—That the 
arms of these animals making continual efforts to embrace easily 
the branches of the trees, will have lengthened ; 2d.—That the nails 
of their toes will have acquired much length and a curved form by 
sustained efforts to cling; 3d.—That their toes, having only exercise 
in particular movements, will have lost all mobility, will have re- 
united, and will have preserved only the ability of bending or of 
traightening themselves altogether ; 4th. —That their thighs, embra- 
cing continually the trunk and the great branches of the trees, will 
have contracted an habitual bowing, which will have helped to 
enlarge the pelvis, and to direct the cotyloid cavities backward 4 
5th.—Finally, that a great number of their bones will have conso 
dated, and that thus many parts of their skeleton will have acquired 
a tendency and a form appropriate to their habits, and contrary sh 
those which they would have had under other habits. 
= No one is able to contest this,since nature, ina thousand other : 
ways, constantly shows us analogous examples of the power of cir- 
