THE TROPICAL FOREST 97 
ripe, there will also be many others. On the other hand, 
just as man has to hunt for individual camphor trees 
in the Formosan forests, or for individual rubber trees 
in the Brazilian forest, so must the fruit-eating wild 
mammals hunt through the forest for the scattered 
trees whose fruits supply their hunger. This is perhaps 
part of the reason why the tropical forest seems to the 
explorer to be deprived of animal life save insects and 
reptiles, part of the reason why the forest mammals 
mostly occur in relatively small numbers. 
If we consider in systematic order the groups of 
animals showing adaptation to life in the tropical forest, 
we naturally begin with the Primates, whose members 
display practically all those characters which we have 
described. Their long arms and short legs, their oppos- 
able thumbs and great toes, their strong clavicles, in 
some instances their prehensile tails, their pectoral 
mammae, and the reduction in the number of young 
at a birth—all these fit them for life among the trees. 
On the other hand, their generalized teeth, the number 
of fingers and toes present, the condition of the bones 
of the limbs, and other characters, show their descent 
from relatively primitive ancestors, specialization show- 
ing itself chiefly in brain development, and in the fact 
that the hands are progressively suited for many uses, 
in addition to their prime function as aids in climbing. 
One point of structure is interesting. Most herbi- 
vorous, or partially herbivorous, animals are specially 
exposed to danger when feeding, for large quantities 
of vegetable food must be taken. Many of the ungulates 
have an arrangement whereby the hastily swallowed 
food can be stored within the alimentary canal, careful 
mastication taking place later. In most of the monkeys, 
on the other hand, food can be temporarily stored in 
1404 G 
