y glimpse of a very tiny corner of the realm of instinct; and
the harvest gathered overwhelms me with its variety: I do not yet know
two species of predatory Wasps whose methods are exactly the same.

One gives a single stroke of the dagger, a second two, a third three, a
fourth nine or ten. One stabs here and the other there; and neither
is imitated by the next, who attacks elsewhere. This one injures the
cephalic centres and produces death; that one respects them and produces
paralysis. Some squeeze the cervical ganglia to obtain a temporary
torpor; others know nothing of the effects of compressing the brain. A
few make the prey disgorge, lest its honey should poison the offspring;
the majority do not resort to preventive manipulations. Here are some
that first disarm the foe, who carries poisoned daggers; yonder are
others and more numerous, who have no precautions to take before
murdering the unarmed prey. In the preliminary struggle, I know some who
grab their victims by the neck, by the rostrum, by the antennae, by the
caudal threads; I know some who throw them on their backs, some who
lift them breast to breast, some who operate on them in the vertical
position, some who attack them lengthwise and crosswise, some who climb
on their backs or on their abdomens, some who press on their backs to
force out a pectoral fissure, some who open their desperately contracted
coil, using the tip of the abdomen as a wedge. And so I could go on
indefinitely: every method of fencing is employed. What could I not also
say about the egg, slung pendulum-fashion by a thread from the ceiling,
when the live provisions are wriggling underneath; laid on a scanty
mouthful, a solitary opening dish, when the dead prey requires renewing
from day to-day; entrusted to the last joint stored away, when the
victuals are paralysed; fixed at a precise spot, entailing the least
danger to the consumer and the game, when the corpulent prey has to be
devoured with a special art that warrants its freshness!

Well, how can this multitude of varied instincts teach us anything
about gradual transformation? Will the one and only dagger-thrust of the
Cerceris and the Scolia take us to the two thrusts of the Calicurgus, to
the three thrusts of the Sphex, to the manifold thrust of the Ammophila?
Yes, if we consider only numerical progression. One and one are two; two
and one are three: so run the figures. But is this what we want to
know? What has arithmetic