Animal coloration : an account of the principal facts and theories relating to the colours and markings of animals / by Frank E. Beddard.

  • Beddard, Frank E. (Frank Evers), 1858-1925.
Date:
1895
Catalogue details

Licence: Public Domain Mark

Credit: Animal coloration : an account of the principal facts and theories relating to the colours and markings of animals / by Frank E. Beddard. Source: Wellcome Collection.

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    pillars, caused simply by the slightly altered pigment (chloro- phyll) derived from their food. Possibly the advent of birds, which are after all the chief foes of caterpillars, caused a necessity for some change of colour, to escape their keen sight. Dr. Weismann has pointed out that green, although thoroughly protective as a colour to leaf-feeding caterpillars while they are small, is not so advantageous later : * the large size of the body alone would render them conspicuous ; but this is remedied by longitudinal or oblique striping, which breaks up the large surface into a number of small areas, and thus renders the insect less conspicuous. It may therefore be wondered why this particular caterpillar has still retained the primitive coloration ; it is as Weismann has said, “ a living fossil.” It must always be remembered, however, that animal life is not stationary ; modification must be going on before our eyes ; and the very fact of the rarity of this caterpillar is so far an argument either that it is becoming extinct owing to its inadaptability, or that it is a variety of some form which has really become modified in the required direction. The fact that many Sphinx larvae just before pupation become brown-coloured is considered by Dr. Weismann to be an adaptation to a change in habit : they rest by day, and descend to the ground for concealment ; a green colour would be therefore not nearly so suitable as brown. But we have to consider the fact that such larvae are dimorphic ; some remain green, others turn brown. This, however, is not to be explained, as suggested by Mr. Poulton (p. 135), as a halving of the risks ; some caterpillars resembling leaves and * It will be noted that this suggestion applies with equal force to tree snakes, frogs, etc., which are usually brought forward as excellent examples of protective coloration (see p. 145) ; they are, of course, much larger, and so the need for breaking up the surface is greater.