THEORIES OF Cor.on-Mve.KINGs oN Enos. The reason for the many and various colorings of birds' eggs has been a favorite field of Spe011lilliDn. and many ingenious theories have been constructed to explain the matter, from the pions musings of Sit Thomas Browne tee the present day. The most important thesis is that advanced by Wallace and enlarged by Poulton, who attempt to show that birds' eggs are examples of protective mim icry in color, as the result of natural selection. Impartial examination shows. however, that only in a minority of cases does the theory of adap tive coloration seem to be adequate and not open to serious interference from other explanations or contradictions: such favorable cases are those of the nightjars, game birds. shore hints. coots, and sonie other ground-builders making scanty whose eggs certainly do closely simulate the beach, or leaves, or marsh-grass upon which they lie. They are certainly very tee especially for human eyes; but most of the de spoilers of birds' nests are not human. but brute foes which. for the most depend less upon their eyes than upon their noses to discover what they seek, and most of which gee about by night rather than by day. Against such foes color is
of small importance among the factors of safety. It is quite probable that in the eases above men tioned the inconspicuous coloring of the eggs is of some consequence, and may be the result in Som• degree: of natural selection: but these eases are only a small part of the whole array of bird life, and 'protective mimicry' certainly fails as yet to account for the coloring of birds' eggs as a whole.
It is much more likely that this phenomenon falls under the theory of 'recognition' colors. .Man• facts go to show that birds recognize their own eggs, and the supposition is reasonable that the tints and markings, if they serve any useful purpose at all, serve that of identification by their owners. This would account for the fact that eggs laid in dark holes are usually white; and it would explain the individual variation within the limits of specific or tribal likeness which universally characterizes the eggs of birds.