THIS excellent work, eagerly awaited for many years, will be most welcome to naturalists, even, we may hope, to the few who have hitherto rejected the Darwinian interpretation which the author has here supported by a mass of additional evidence based on his own observations and those of very many others. Dr. Julian Huxley, in his introduction, refers to one of these critics, the American zoologist, A. F. Shull, who writes in contemptuous terms of the whole subject. To this Huxley replies: “Dr. Cott, in this important book, has turned the tables with a vengeance on objectors of this type. He has shown that it is they who are the armchair critics, or, one might say, the laboratory-bench critics. Had they taken the trouble to acquaint themselves with even a fraction of the relevant facts to be found in nature, they could never have ventured to enunciate such sweeping criticisms”. Adaptive Coloration in Animals By Dr. Hugh B. Cott. Pp. xxxii + 508 + 49 plates. (London: Methuen and Co., Ltd., 1940.) 40s. net.