, as they had pieces torn out of the wing, sometimes
symmetrically out of both wings, showing that the insect had been seized
when at rest and with the two pairs of wings in contact. There is,
however, a general impression that this knowledge is hereditary, and
does not need to be acquired by young birds; in support of which view
Mr. Jenner Weir states that his birds always disregarded inedible
caterpillars. When, day by day, he threw into his aviary various larvae,
those which were edible were eaten immediately, those which were
inedible were no more noticed than if a pebble had been thrown before
the birds.

The cases, however, are not strictly comparable. The birds were not
young birds of the first year; and, what is more important, edible
larvae have a comparatively simple coloration, being always brown or
green and smooth. Uneatable larvae, on the other hand, comprise all that
are of conspicuous colours and are hairy or spiny. But with butterflies
there is no such simplicity of contrast. The eatable butterflies
comprise not only brown or white species, but hundreds of Nymphalidae,
Papilionidae, Lycaenidae, etc., which are gaily coloured and of an
immense variety of patterns. The colours and patterns of the inedible
kinds are also greatly varied, while they are often equally gay; and it
is quite impossible to suppose that any amount of instinct or inherited
habit (if such a thing exists) could enable young insectivorous birds to
distinguish all the species of one kind from all those of the other.
There is also some evidence to show that animals do learn by experience
what to eat and what to avoid. Mr. Poulton was assured by Rev. G.J.
Bursch that very young chickens peck at insects which they afterwards
avoid. Lizards, too, often seized larvae which they were unable to eat
and ultimately rejected.

Although the Heliconidae present, on the whole, many varieties of
coloration and pattern, yet, in proportion to the number of distinct
species in each district, the types of coloration are few and very well
marked, and thus it becomes easier for a bird or other animal to learn
that all belonging to such types are uneatable. This must be a decided
advantage to the family in question, because, not only do fewer
individuals of each species need to be sacrificed in order that their
enemies may learn the lesson of their inedibility, but they are more
easily recognised at a distance, and thus escape even pursuit. There is
thus