Iv ON PLANT LIFE 157 
plant is by no means the only service which 
insects render. 
Ants, for instance, are In many cases very 
useful to plants. They destroy immense 
numbers of caterpillars and other insects. 
Forel observing a large Ants’ nest counted 
more than 28 insects brought in as food per 
minute. In some cases Ants attach them- 
selves to particular trees, constituting a sort 
of bodyguard. A species of Acacia, described 
by Belt, bears hollow thorns, while each leaflet 
produces honey in a crater-formed gland at 
the base, as well as a small, sweet, pear- 
shaped body at the tip. In consequence it 
is inhabited by myriads of a small ant, which 
nests in the hollow thorns, and thus finds 
meat, drink, and lodging all provided for it. 
These ants are continually roaming over the 
plant, and constitute a most efficient body- 
guard, not only driving off the leaf-eating 
ants, but, in Belt’s opinion, rendermg the 
leaves less liable to be eaten by herbivorous 
mammalia. Delpino mentions that on one 
occasion he was gathering a flower of Clero- 
dendrum, when he was himself suddenly 
attacked by a whole army of small ants. 
