having in her mandibles the pellet of mortar required
for the immediate construction of the lid of the nest. The precious
egg must not for a single instant remain exposed to the cupidity of
marauders.

To these particulars I will add a few general observations which will
make what follows easier to understand. So long as its circumstances are
normal, the insect's actions are calculated most rationally in view of
the object to be attained. What could be more logical, for instance,
than the devices employed by the Hunting Wasp when paralysing her prey
(Cf. "Insect Life": chapters 3 to 12 and 15 to 17.--Translator's Note.)
so that it may keep fresh for her larva, while in no wise imperilling
that larva's safety? It is preeminently rational; we ourselves could
think of nothing better; and yet the Wasp's action is not prompted by
reason. If she thought out her surgery, she would be our superior. It
will never occur to anybody that the creature is able, in the smallest
degree, to account for its skilful vivisections. Therefore, so long
as it does not depart from the path mapped out for it, the insect can
perform the most sagacious actions without entitling us in the least to
attribute these to the dictates of reason.

What would happen in an emergency? Here we must distinguish carefully
between two classes of emergency, or we shall be liable to grievous
error. First, in accidents occurring in the course of the insect's
occupation at the moment. In these circumstances, the creature is
capable of remedying the accident; it continues, under a similar form,
its actual task; it remains, in short; in the same psychic condition.
In the second case, the accident is connected with a more remote
occupation; it relates to a completed task with which, under normal
conditions, the insect is no longer concerned. To meet this emergency,
the creature would have to retrace its psychic course; it would have
to do all over again what it has just finished, before turning its
attention to anything else. Is the insect capable of this? Will it be
able to leave the present and return to the past? Will it decide to hark
back to a task that is much more pressing than the one on which it was
engaged? If it did all this, then we should really have evidence of a
modicum of reason. The question shall be settled by experiment.

We will begin by taking a few incidents that come under the first
heading. A Mason-bee has finished the initial layer of the cov