68 
ANIMAL INTELLIGENCE. 
in which these wonderful insects enslave insects of another 
species, which therefore may be said to stand to the ants 
in the relation of beasts of burden. The case to which I 
allude is one that is recorded in Perty’s ‘ Intellectual Life 
of Animals 5 (2nd ed. p. 329), and is as follows : — 
According to Audubon certain leaf-bugs are used as slaves 
by the ants in the Brazilian forests. When these ants want to 
bring home the leaves which they have bitten off the trees, 
they do it by means of a column of these bugs, which go in 
pairs, kept in order on either side by accompanying ants. They 
compel stragglers to re-enter the ranks, and laggards to keep 
up by biting them. After the work is done the bugs are shut 
up within the colony and scantily fed. 
Wars . — On the wars of ants a great deal might be said, 
as the facts of interest in this connection are very nume- 
rous i but for the sake of brevity I shall confine myself to 
giving only a somewhat meagre account. 
One great cause of war is the plundering of ants 5 nests 
by the slave-making species. Observers all agree that this 
plundering is effected by a united march of the whole 
army composing a nest of the slave-making species, 
directed against some particular nest of the species which 
they enslave. According to Lespes and For el, single scouts 
or small companies are first sent out from the nest to ex- 
plore in various directions for a suitable nest to attack. 
These scouts afterwards serve as guides to the marauding 
excursion. Forel saw several of these scouts of the species 
F. rufescens or Amazon carefully inspecting a nest of 
F. fusca which they had found, investigating especially 
the entrances. These are purposely made difficult to find 
by their architects, and it not unfrequently happens that 
after all precautions and inspections on the part of the 
invaders, an expedition fails on account of not finding the 
city gates. 
When the scouts have been successful in discovering a 
suitable nest to plunder, and have completed their stra- 
tegical investigations of the locality to their satisfaction, 
they return straight to their own nest or fortress. Forel 
has then seen them walking about on the surface of theii 
nest for a long time, as if in consultation, or making up 
