The Colours of Guillemots' Eggs

YOUR reviewer, in dealing with Mr. R. J. Ussher's work on the birds of Ireland (see NATURE, November 29, 1900, pp. 101 and 102), had his attention particularly drawn to two statements concerning the eggs of the guillemot. In the first of these, which occurs on p. 364 of his book, Mr. Ussher puts forward the suggestion that “the beautiful varieties of colouring must help each bird to distinguish her egg from others lying near until they all become stained and soiled” (the italics are mine). This is certainly a very pretty hypothesis; but is not the earlier part contradicted by the part I have italicised? It is certainly indirectly contradicted by a statement on p. 365, where Mr. Ussher records his belief that when the eggs of the guillemot are found, as they sometimes are, in the nests of cormorants and kittiwakes, “the owners of the nest incubate the mixed clutches, and not the guillemots, for I have noticed (he writes) a kittiwake chase away one of the latter from its nest.”