THE TROPICAL FOREST 119 
and it can also leap and skip over the mud. The eyes 
are very prominent, are furnished with distinct eyelids, 
and are protrusible. The fish, which are very tadpole- 
like in appearance, feed upon insects. 
In India and the south-east of Asia generally, another 
fish is found which can live on land, and voluntarily 
leaves the water to do so. This is the climbing perch 
(Anabas scandens), a freshwater form which travels 
long distances over land by hitching its pectoral fins 
round plants. The fish is also stated to be able to 
climb trees. It has a special accessory breathing organ, 
which enables it to breathe air when out of the water. 
In regard to the invertebrates, a special feature of 
the tropical forests is the great wealth of insects. That 
this must be so will be clear when we reflect that 
some of the forest-dwelling primates, the insectivores, 
many of the marsupials, some carnivores, the eden- 
tates, many reptiles and amphibians and so on, eat 
insects, either solely or in combination with other types 
of food. Further, the equal temperature allows the 
insects to go on breeding all the year round, and thus 
permits a great wealth of individuals to occur, while 
the special conditions favour a great wealth of genera 
and species. Apart from the size and beauty of the 
tropical butterflies, the most impressive of the insects 
are first the flies, which are often blood-suckers, and 
then may, as in the case of mosquitoes and tsetse flies, 
serve as transmittors of the tropical diseases most fatal 
to man and beast, and second the ants, some of which 
are extraordinarily destructive to plant life, while 
others from their numbers and ferocity are the enemies 
of all other animals. The driver ants of West Africa, 
which are wandering forms, are stated to devour every 
living creature in their path which cannot make its 
