It is of course advantageous in some ways to have agreement as to the limitations of ecology, or any science, but even the more exact sciences seem to fare little better, as is shown by the following statement: “It is not long since I heard a university professor begin a lecture on physics somewhat in this way: ‘Physics is the science of matter and energy. This field is so large that it is customary at present to break off the physics of the molecule and its reactions and call it chemistry. Also to put to one side the physics of the heavenly bodies and call this a part of astronomy,’ etc.” (Strong, Science, N. S., Vol. XXXIV, p. 409, 1911.) FORBES, S. A. 1895. On Contagious Disease in the Chinch-Bug (_Blissus leucopterus_ Say). 19th Rep. State Ent. Ill. (8th Rep. of S. A. Forbes), pp. 16-176. In this paper Forbes defines (pp. 16-18) ecology and points out, I believe for the first time, that economic entomology is simply applied ecology. He says, “The study of œcology is thus to the economic entomologist what the study of physiology is to the physician.” 1909. Aspects of Progress in Economic Entomology. Journ. Econ. Ent., Vol. II, pp. 25-35. Especially pp. 28-32 on the relation of ecology to economic entomology. HERDMANN, W. A. 1896. Oceanography, Bionomics, and Aquiculture. Smithsonian Report for 1895, pp. 433-454. EMERY, C. 1905. Éthologie, Phylogénie et Classification. C. R. 6me Cong. inter. de Zool. Berne, 1904, pp. 160-174. CLEMENTS, F. E. 1905. The Foundations of Ecology, pp. 1-17. Research Methods in Ecology, pp. 334. Lincoln, Nebraska. ADAMS, CHAS. C. 1906. Introductory Note. An Ecological Survey in Northern Michigan. Ann. Rep. Mich. Geol. Surv. for 1905, pp. 11-12. 1909. The Ecological Succession of Birds. Ann. Rep. Mich. Geol. Surv. for 1908, pp. 121-154. SHELFORD, V. E. 1912. Ecological Succession. V. Aspects of Physiological Classification. Biol. Bull., Vol. XXIII, pp. 331-370. The standpoint of this paper is very much in harmony with that advanced in this book. CASE, E. C. 1905. Œcological Features of Evolution. Bull. Wis. Nat. Hist. Soc., Vol. III, pp. 169-180. WHEELER, W. M. 1905. Ethology and the Mutation Theory. Science, N. S., Vol. XXI, pp. 535-540. FLAHAULT, C., and SCHRÖTER, C. 1910. Phytogeographical Nomenclature. Reports and Propositions. IIIᵉ Cong. Inter. de Botanique. Bruxelles, 1910. pp. 28 + x. Zurich. WHITE, C. A. 1893. The Relation of Biology to Geological Investigation. Ann. Rep. U. S. Nat. Mus. for 1892, pp. 245-368. This paper and the two following references illustrate the intimate relation of ecology to phases of geology. GRABAU, A. W. 1899. The Relation of Marine Bionomy to Stratigraphy. Bull. Buffalo Soc. Nat. Sci., Vol. VI, pp. 319-367. WALTHER, J. 1893-94. Einleitung in die Geologie als historische Wissenschaft. I. Bionomie des Meeres. II. Die Lebensweise der Meeresthiere. III. Lithogenesis der Gegenwart. Jena.