11 ON ANIMAL LIFE 59 
course be useless. The workers do not, except 
- occasionally, lay eggs, but carry on all the af- 
fairs of the community. Some of them, and 
especially the younger ones, remain in the 
nest, excavate chambers and tunnels, and tend 
the young, which are sorted up according to 
age, so that my nests often had the appear- 
ance of a school, with the children arranged 
in classes. 
In our English Ants the workers in each 
species are all similar except in size, but 
among foreign species there are some in which 
there are two or even more classes of workers, 
differing greatly not only in size, but also in 
form. The differences are not the result of 
age, nor of race, but are adaptations to 
different functions; the nature of which, 
however, is not yet well understood. Among 
the Termites those of one class certainly seem 
to act as soldiers, and among the true Ants 
also some have comparatively immense heads 
and powerful jaws. It is doubtful, however, 
whether they form a real army. Bates 
observed that on a foraging expedition the 
large-headed individuals did not walk in the 
