mammals, and the skin of all the Snakes and Lizards, is of one uniform isabelline or sand colour."[1] Brehm writes:—"The birds, the reptiles, and even the insects show the same stamp, though form and colouring may vary greatly. When any other colour besides sandy yellow becomes prominent, if hair, feather, or scale be marked with black or white, ashy grey or brown, red or blue, such decorations occur only in places where they are not noticeable when looked at from above or from the side."[2] But he also remarks:—"The fact that almost all the desert animals agree in colouring with their surroundings explains why the traveller who is not an experienced observer often sees, at first at least, but little of the animal life."[3] This appears to better illustrate the survival of an original assimilative colouration than to afford an example of the strict definition of what is meant as "protective resemblance," which affords an extraneous means of survival under an increased competition of life. Mr. Beddard, discussing the effects of temperature and moisture on the colours of animals, considers it "at least possible that the tawny colours of desert animals, which have been so often brought forward as an instance of adaptation to the hues of their environment, may be due to a similar cause."[4] Mr. Quelch, writing on the Birds
- ↑ 'Ibis,' vol. i. p. 429. I do not remember meeting with this remark in the Canon's 'Great Sahara,' and it may have been an observation recalled when the specimens were more closely examined. Such reflections are no less valuable when subsequent considerations. Some exceptions to this rule were, however, given by Canon Tristram to Mr. Darwin: "Thus the male of Monticola cyanea is conspicuous from his bright blue colour, and the female almost equally conspicuous from her mottled brown and white plumage; both sexes of two species of Dromolæa are of a lustrous black; so that these three species are far from receiving protection from their colours; yet they are able to survive, for they have acquired the habit of taking refuge from danger in holes or crevices in the rocks" ('Descent of Man,' second edition, p. 456). According to Dr. Merriam: "The theory of the direct action of environment in modifying colour, as in the bleached types of the desert regions, is not borne out by observations, and is disproved in the case of nocturnal types" (Balt. Meet. Am. Soc. Nat.; see 'Science,' new ser. vol. i. p. 38). Another American authority—Mr. Orr—accepts the theory, and remarks:—"Living matter seems to be in a general way capable to a certain extent of photographing colours when exposed for many generations" ('A Theory of Development and Heredity,' p. 50).
- ↑ 'From North Pole to Equator,' p. 336.
- ↑ Ibid. p. 331.
- ↑ 'Animal Coloration,' 2nd edit. p. 60.
