way
alter its external shape. After any moult that it may have undergone,
the larva retains the same characteristics. If it begin by being
tough, it will not become tender; if it be equipped with legs, it will
not be deprived of them later; if it be provided with ocelli, it will
not become blind. It is true that the diet of these non-variable
larvae remains the same throughout their duration, as do the
conditions under which they are destined to live.

But suppose that this diet varies, that the environment in which they
are called upon to live changes, that the circumstances accompanying
their development are liable to great changes: it then becomes evident
that the moult may and even must adapt the organization of the larva
to these new conditions of existence. The primary larva of the Sitaris
lives on the body of the Anthophora. Its perilous peregrinations
demand agility of movement, long-sighted eyes and masterly
balancing-appliances; it has, in fact, a slender shape, ocelli, legs
and special organs adapted to averting a fall. Once inside the Bee's
cell, it has to destroy the egg; its sharp mandibles, curved into
hooks, will fulfil this office. This done, there is a change of diet:
after the Anthophora's egg the larva proceeds to consume the ration of
honey. The environment in which it has to live also changes: instead
of balancing itself on a hair of the Anthophora, it has now to float
on a sticky fluid; instead of living in broad daylight, it has to
remain plunged in the profoundest darkness. Its sharp mandibles must
therefore become hollowed into a spoon that they may scoop up the
honey; its legs, its cirri, its balancing-appliances must disappear as
useless and even harmful, since all these organs can only involve the
larva in serious danger, by causing it to stick in the honey; its
slender shape, its horny integuments, its ocelli, being no longer
necessary in a dark cell where movement is impossible, where there are
no rough encounters to be feared, may likewise give place to complete
blindness, to soft integuments, to a heavy, slothful form. This
transfiguration, which everything shows to be indispensable to the
life of the larva, is effected by a simple moult.

We do not so plainly perceive the necessity of the subsequent forms,
which are so abnormal that nothing like them is known in all the rest
of the insect class. The larva which is fed on honey first adopts a
false chrysalid appearance and afterwards g