utes she munches
this weak spot, which lies close to the cerebral nerve-centres. The
pincers squeeze suddenly but at intervals and methodically, as though
the manipulator wished each time to judge of the effect produced; the
squeezes are repeated until I am tired of trying to count them. When
they cease, the caterpillar's mandibles are motionless. Then comes the
transportation of the carcase, a detail which is not relevant in this
place.

I have set forth the complete tragedy, as it is fairly often enacted,
but not always. The insect is not a machine, unvarying in the effect
of its mechanism; it is allowed a certain latitude, enabling it to
cope with the eventualities of the moment. Any one expecting to see
the incidents of the struggle unfolding themselves exactly as I have
described will risk disappointment. Special instances occur--they are
even numerous--which are more or less at variance with the general rule.
It will be well to mention the more important, in order to put future
observers on their guard.

Not infrequently the first act, that of paralysing the thorax, is
restricted to two thrusts of the sting instead of three, or even to one,
which is then delivered in the foremost segment. This, it would seem,
from the persistency with which the Ammophila inflicts it, is the most
important prick of all. Is it unreasonable to suppose that the operator,
when she begins by pricking the thorax, intends to subdue her capture
and to make it incapable of injuring her, or even of disturbing her when
the moment comes for the delicate and protracted surgery of the second
act? This idea seems to me highly admissible; and then, instead of three
dagger-thrusts, why not two only, why not merely one, if this would
suffice for the time being? The amount of vigour displayed by the
caterpillar must be taken into consideration. Be this as it may, the
segments spared in the first act are stabbed in the second. I have
sometimes even seen the three thoracic segments stung twice over: at
the beginning of the attack and again when the Wasp returned to her
vanquished prey.

The Ammophila's triumphant transports beside her wounded and writhing
victim are also subject to exceptions. Sometimes, without releasing
its prey for a moment, the insect proceeds from the thorax to the next
segments and completes its operation in a single spell. The joyous
entr'acte does not take place; the convulsive movements of the wings and
the acrobatic postu