rve
certain facts which put us on the road of explanation.

An interesting member of the Hymenoptera, the _Sphex_, assures food
for the early days of the life of its larvae in a curious way.[7]
Before laying its eggs it seizes a cricket, paralyses it with two
strokes of its sting--one at the articulation of the head and the
neck, the other at the articulation of the first ring of the thorax
with the second--each stab traversing and poisoning a nervous
ganglion. The cricket is paralysed without being killed; its flesh
does not putrefy, and yet it makes no movement. The _Sphex_ places an
egg on this motionless prey, and the larva which emerges from it
devours the cricket. Here assuredly is a marvellous and certain
instinct. One cannot even object that the strokes of the sting are
inevitably directed to these points because the chitinous envelope of
the victim offers too much resistance in other spots for the dart to
penetrate, because here is the _Ammophila_, a near relative of the
_Sphex_, which chooses for its prey a caterpillar. It is free to
introduce its sting into any part of the body, and yet with extreme
certainty it strikes the two ganglions already mentioned.[8]

[7] "Etude sur l'Instinct et les Metamorphoses des
Sphegiens," _Ann. Sc. Nat._, iv. Serie, t. 6, 1856.

[8] P. Marchal, "Observations sur _l'Ammophila affinis_,"
_Arch. de Zool. exper. et gener._, ii. Serie, t. 10, 1892.

We cannot suppose that the insect has anatomical and physiological
knowledge to inform it of what it is doing. The act is distinctly
instinctive, and seems imprinted by a fatality involving no possible
connection with intelligence. But let us suppose that the ancestors of
these Hymenoptera have thus attacked crickets and killed (not
paralysed) them with one or more wounds at any point. By chance some
of these insects, either in consequence of their manner of attacking
the prey or from any other cause, happen to deliver their blows at the
points in question. Their larvae on this account are placed in more
favourable conditions than those of their relatives whom chance has
less well served; they will prosper and develop sooner. They inherit
this habit, which gradually becomes through the ages that which we
know. It is possible; but why, it may be asked, this hypothesis,
apparently gratuitous, of strokes of the sting given at random? Are
there any facts which render this explanation plausible? Assuredly.
Thus