bout its preferences. To feed its carnivorous larvae
it levies tribute on every species of game which is not too much for
the huntress' power or the nurseling's appetite; its descendants try
now this, now that, now something else, at random, until the accumulated
centuries lead to the selection which best suits the race. Then habit
grows fixed and becomes instinct.

Very well. Let us agree that the Scolia of antiquity sought a different
prey from that adopted by the modern huntress. If the family throve upon
a diet now discontinued, we fail to see that the descendants had any
reason to change it: animals have not the gastronomic fancies of an
epicure whom satiety makes difficult to please. Because the race did
well upon this fare, it became habitual; and instinct became differently
fixed from what it is to-day. If, on the other hand, the original food
was unsuitable, the existence of the family was jeopardized; and any
attempt at future improvement became impossible, because an unhappily
inspired mother would leave no heirs.

To escape falling into this twofold trap, the theorists will reply that
the Scoliae are descended from a precursor, an indeterminate creature,
of changeable habits and changing form, modifying itself in accordance
with its environment and with the regional and climatic conditions and
branching out into races each of which has become a species with the
attributes which distinguish it to-day. The precursor is the deus
ex machina of evolution. When the difficulty becomes altogether
too importunate, quick, a precursor, to fill up the gaps, quick, an
imaginary creature, the nebulous plaything of the mind! This is seeking
to lighten the darkness with a still deeper obscurity; to illumine the
day by piling cloud upon cloud. Precursors are easier to find than sound
arguments. Nevertheless, let us put the precursor of the Scoliae to the
test.

What did she do? Being capable of everything, she did a bit of
everything. Among its descendants were innovators who developed a taste
for tunnelling in sand and vegetable mould. There they encountered the
larvae of the Cetonia, the Oryctes, the Anoxia, succulent morsels on
which to rear their families. By degrees the indeterminate Wasp adopted
the sturdy proportions demanded by underground labour. By degrees she
learnt to stab her plump neighbours in scientific fashion; by degrees
she acquired the difficult art of consuming her prey without killing it;
at length,