And yet the protection is very real, for the larvae will be passed over by those who are not accustomed to their appearance, although the searcher may be told of the presence of a large caterpillar.

An experienced entomologist may also fail to find the larvae till after a considerable search.

This is general protective resemblance, and it depends upon a general harmony between the appearance of the organism and its whole environment.

It is impossible to understand the force of this protection for any larva, without seeing it on its food-plant and in an entirely normal condition.
The artistic effect of green foliage is more complex than we often imagine; numberless modifications are wrought by varied lights and shadows upon colours which are in themselves far from uniform.

In the larva of Papilio machaon the protection is very real when the larva is on the food-plant, and can hardly be appreciated at all when the two are apart." Numerous other examples are given in the chapter on "Mimicry and other Protective Resemblances among Animals," in my _Contributions to the Theory of Natural Selection_.] [Footnote 70: _The Naturalist in Nicaragua_, p.