Methods of camouflage covered include background matching, resemblance to specific objects such as bird droppings, self-decoration with materials from the environment, and the seasonal colour change of arctic animals.

Finally Poulton summarizes the subject with a fold-out table including a set of Greek derived words that he invented, of which "aposematic" and "cryptic" survive in biological usage.

The Colours of Animals was well received on its publication, although the book's support for sexual selection was criticised by Alfred Russel Wallace, and its Darwinism and critique of Lamarckism were attacked by Edward Drinker Cope.

When, however, he admits that display of their decorative plumage by male birds is 'demonstrated', and that the females are in all probability 'pleased or excited by the display', he certainly admits the possession of an aesthetic sense...In The Colours of Animals, Poulton introduced the concept of frequency-dependent selection (selection based on how abundant a form is) in the context of a polymorphism which he argued would otherwise soon vanish:[2][P 4] If we breed from moths developed from the green larvae of, e.g., the Large Emerald, the larvae in the next generation are chiefly green, and after several generations there is little doubt that the brown form would become excessively rare; so also the green form would disappear if we bred from the brown varieties.

In the former case the foes have a wider range of objects for which they may mistake the larvae, and the search must occupy more time, for equivalent results, than in the case of other species which are not dimorphic.The basic concept of warning coloration (aposematism, like the black and yellow pattern of a wasp) is approached very simply: When an animal possesses an unpleasant attribute, it is often to its advantage to advertise the fact as publicly as possible.

Even the presence of numerous dark twigs has been shown to cause a corresponding change of colour in the larva of the peppered moth (Amphidasis betularia).

He begins by stating "Mr. Poulton fully accepts Darwin's theory of female choice as the source of the greater part of the brilliant colour, delicate patterns, and ornamental appendages that exist among animals, and especially among birds and insects."

Wallace then cites Poulton on the courtship behaviour of spiders: "'The female always watches the antics of the male intently, but often refuses him in the end, 'even after dancing before her for a long time.'

Such observations strongly point towards the existence of female preference based on æsthetic considerations'"[6]at once objecting "To the last four words we demur, as being altogether unproved.

[6] Wallace gives a detailed counter-example to refute Poulton's argument, arguing that "really beautiful combinations of colour and marking" are found on the sea shells of molluscs "where sexual selection has certainly not come into play".

To make the point, Wallace lists[6] "the cones, cowries, olives, harps, volutes, pectens, and innumerable other molluscan shells; while many of the sea-anemones, and considerable numbers of the caterpillars with warning colours, are equally beautiful.

[6] After so many "preceding remarks" against "the theory of sexual selection", Wallace concludes that "The book is well illustrated by numerous excellent woodcuts and a coloured plate", congratulates Poulton on "having produced so readable and suggestive a volume", and on having "contributed so largely" by "his own researches" into animal coloration.

The reviewer hastens to agree that Poulton is in fact "ready to combat Wallace, his master, on points wherein that great fellow-laborer with Charles Darwin dissents from the latter's views.

[7] The Neo-Lamarckian[5] Edward Drinker Cope, reviewing the book for the American Naturalist, wrote that "Mr. Poulton supports his own theory of the direct physiological value of the uses of colour to animals by a large amount of experimental evidence brought together from many sources".

Cope is attracted by "a detail of great interest" in a caterpillar's camouflage "by the semblance of a small hole to indicate piercing by insect larvae" (ichneumon flies, since they avoid caterpillars that are already parasitised), and is impressed by Poulton's observations of "perhaps the most perfect concealment attained by any butterfly" in the dead leaf butterfly Kallima, first described by Alfred Russel Wallace.

"[10] The reviewer notes more critically that additional examples of mimicry might have been given, such as of Hymenoptera (bees and wasps) mimicked by Diptera (flies), and would have liked fuller treatment of Bates's "South American heliconids and pierids".

"[10] The review ends with a brief discussion of Poulton's table classifying animal coloration, predicting (correctly) that the "Greek derivatives" such as pseudaposematic and pseudepisematic will not be generally adopted.

The reviewer writes that it is among Lepidoptera (butterflies and moths) that "protective resemblance or 'cryptic coloration' is most beautifully illustrated, and the book teems with instances" of these, noting that Poulton had "made this part of the subject his own".

She suggests that while people have therefore taken Poulton for a staunch Darwinist and supporter of sexual selection, he "lost his initial enthusiasm for the theory" and "came to relegate it to a very minor position" in evolution.