calls the “tension zone,” because a constant state of strain or tension in the struggle for existence prevails in it. In the deciduous zone the geological formations are numerous, with various soils and every gradation of topography, and the diversity of trees is great. Its southern line is coterminous with the southern edge of the Triassic formation. The coniferous zone presents but little diversity in geology or topography, and little variety of trees. Its northern border is coterminous with the northern border of Tertiary gravels, sands, and sandy clays. The “tension zone” includes practically the whole of the Cretaceous plastic clays, and the clay-marls and marls. MINOR PARAGRAPHS. A conference was appointed, to be held at Wiesbaden, Germany, October 9th and 10th, to promote the formation of an International Federation of Science--a scheme which was referred to in Sir Michael Foster’s presidential address before the British Association. This idea for the establishment of an international association of great learned societies appears, the London Athenæum says, to be the outcome of discussions carried on at Göttingen in 1898. For some time past the Academies of Vienna, Munich, Göttingen, and Leipsic have been federated into an association or “Castell,” each meeting in turn at their respective headquarters to talk over scientific matters of joint interest. At two or three recent meetings questions were brought up, such as antarctic research and the cataloguing of scientific literature, which, besides being of sufficient interacademic value to come before the “Castell,” were of prime importance to English men of science. English delegates were therefore invited to attend, and did so; and out of this invitation has grown a desire for a wider international basis for the association. The adherence of the principal learned societies of the world, including our National Academy, is said to have been secured to the movement. * * * * * The thirteenth season of the Department of Botany at the Marine Biological Laboratory, Woods Holl, Mass., will open July 5th and continue till August 16th. Three laboratory courses are provided, accompanied by lectures, including the subjects of cryptogamic botany, plant physiology, and plant cytology and micro-technique. The principal instructors are Dr. Bradley R. Davis, Mr. George T. Moore, and Dr. Rodney H. True. The department extends a special welcome to investigators, and desires their co-operation in the development of the laboratory. Woods Holl offers great attractions in variety of material and facilities for biological research, and is proposed as an excellent center of resort where the botanists of the country may meet for a few weeks. A six weeks’ course in Nature study, including both animals and plants, and consisting largely of field work, is a new feature offered this year for the first time. * * * * *