. Even if you come across the armies in full
combat, and you remove from the ranks an ant belonging to either side
and shut the two by themselves in a small box, they will do one another
no harm. If, instead of taking merely two, you shut up a moderate number
from either side within a narrow space, they will fight half-heartedly
for a while, but soon cease to struggle, and often end by making
friends. In such circumstances, says Forel, they will never resume the
struggle. But put these same ants back among the fighting forces of
their respective sides, and separate them by a reasonable distance, so
that they might live at peace, and you will see them return to the
attack; the individuals which a moment before were avoiding one another
with repugnance or fear, will now furiously engage in mutual
slaughter.[80] It thus appears that the combative instinct is a
collective contagion.

Sometimes this epidemic assumes unmistakably morbid attributes.[81] In
proportion as it extends and in proportion as the struggle is prolonged,
the fighting rage becomes a positive frenzy. The very same ant, which at
the outset was timid, will now be affected with a paroxysm of furious
madness. She no longer knows what she is about. She throws herself upon
her own companions, kills the slaves that are endeavouring to calm her,
bites everything she touches, bites fragments of wood, can no longer
find her way. Other members of the community, slaves as a rule, have to
surround such a frenzied worker by twos and threes; they seize her by
the legs and caress her with their antennae until she comes to herself,
has recovered as I might say "her reason." Why not? Had she not lost it?

We have hitherto been dealing exclusively with general phenomena, those
which obey fairly rigid laws. Now we are faced with special phenomena
wherein initiative conflicts in the most peculiar way with the instinct
of the species, and, which is yet more curious, in the end causes
instinct to stray from its appointed path, and even to die out
altogether.

Forel places in a jar some ants of enemy species, the sanguinea and the
pratensis. After a few days of warfare, followed by a sullen armistice,
he introduces a newly hatched pratensis which is very hungry. She runs
to those of her own species begging them to feed her. The pratenses fob
her off. Then the poor innocent appeals to the enemies of her species,
the sanguineae, and, after the manner of ants, she licks the mouth