1. It takes any 6, 9 or 15 volt automobile headlight lamp, and does not require a special filament lamp. 2. Any standard base receptacle may be used, such parts being easily interchangeable. 3. It operates on the ordinary 110 volt 60 cycle lighting circuit by the use of a 40 watt transformer giving three secondary voltages: 6, 9 and 15 volts. 4. It gives a sharply defined, brilliantly lighted spot, with either black or white line image, readily seen in direct sunshine from distances of 30 to 50 feet through an unusually wide angle, rendering the equipment valuable for lecture demonstration. 5. It may be used with any plane or concave galvanometer mirror, the definition of the image being equal in either case. 6. Its indications are standard 1⁄2 metermillimeter deflections. 7. It is conveniently portable and easily assembled for use. Good deliveries for early orders PYROLECTRIC INSTRUMENT CO. 636-640 EAST STATE STREET Naturalists' Supplies We carry a stock for prompt delivery I. Collecting Utensils. II. Breeding Apparatus and Cages for Living III. Preparing and Preserving Utensils. V. Magnifiers, Microscopes and Accessories. VI. Botanists' Supplies. VII. Explorers' and Collectors' Camp Outfits. VIII. Miscellaneous Naturalists' Supplies. IX. Oologists' Supplies. X. Aquaria. XI. Books and Publications XII. Chemicals K-S Museum Cabinets of Glass and Metal Catalogue, Circular or Information on application THE KNY-SCHEERER CORPORATION We have been handling Natural History Material of all kinds for the past fifty years, and so have accumulated a very complete stock. Our prices are as low as the quality of the specimens will permit. We are constantly preparing circulars and price lists covering our material in the different branches, which we will be pleased to send free of charge to the readers of Science. Some of our recent circulars: S-121 Rare Bird Skins S-110 Complete Trilobites S-111 Jurassic Fossils S-119 Cretaceous Fossils CONCHOLOGY GEOLOGY WILEY-Beverages and their Adulterations By HARVEY W. WILEY, M.D., Formerly Chief of Bureau of Chemistry, U. S. Department From the Preface: The rapidly increasing use of fruit juices demands a prominent place in Proper space is given to a discussion of coffee, and related products, tea, cocoa, chocolate. MAXTED-Catalytic Hydrogenation and By EDWARD B. MaxTED, Ph.D., B.Sc., F.C.S. It presents in accessible form the numerous examples of catalytic hydrogenation which have WILLOWS and HATSCHEK-Surface Their Influence on Chemical Phenomena By R. S. WILLOWS, M.A., D.Sc., and EMIL HATSCHEK. Second Edition, Revised. 21 GAGER-Laboratory Guide to General Botany Second Edition By C. STUART GAGER, Director, Brooklyn Botanic Garden. Second Edition. 12mo. Pp. P. BLAKISTON'S SON & CO. PUBLISHERS PHILADELPHIA Spencer Microscopes Embody a side-fine adjustment (the critical mechan- I. Simplest-fewer parts-less to get out of order. II. 34 threads of the screw engaged as compared with the equivalent of but one in others. III. It has a "lateral travel"-an index to its position, relative to its limits. IV. It is fool-proof durable. It cannot be forced beyond its limits-steel stops prevent. These advantages are the result of our many years of pioneering in side-fine adjustment construction. Catalog sent on application Marine Biological Laboratory Woods Hole, Mass. INVESTIGATION Entire Year INSTRUCTION July 2 to August 12, 1919 SUPPLY DEPARTMENT Open the Entire Year Facilities for rescach in Zoology. Embryology, Physiology and Botany. Seventy-six private laboratories, $100 each for not over three months. Thirty tables are available for beginners in research who desire to work under the direction of members of the staff. The fee for such a table is $50.00. Courses of laboratory instruction with lectures are offered in Invertebrate Zoology, Protozoology, Embryology, Physiology and Morphology and Taxonomy of the Algae. Each course requires the full time of the student. Fee, $50. A lecture course on the Philosophical Aspects of Biology and Allied Sciences is also offered. Animals and plants, preserved, livi ng, and in embryonic stages. Preserved material of all types of animals and of Algae, Fungi, Liverworts and Mosses furnished for classwork, or for the museum. Living material furnished in season as ordered. Microscopic slidesin Zoology, Botany, Histology, Bacteriology. Price lists of Zoological and Botanical material and Microscopic Slides sent on application. State which is desired. For price lists and all information regarding material, address GEO. M. GRAY, Curator, Woods Hole, Mass. The annual announcement will be sent on application to The Director, Marine Biological Laboratory, Woods Hole, Mass. THE ELECTRON Its Isolation and Measurement By ROBERT A. MILLIKAN xii+268 pages. Cloth, $1.50, postage extra. (Weight, 1 lb. 3 oz.) The author discusses the bearing of the atomic structure of electricity and the electron as related to the two most important problems of modern physics: the structure of the atom and the nature of electromagnetic radiation. "The book merits the attention of all ORDER FROM YOUR DEALER OR FROM The University of Chicago Press Publications of Carnegie Institution of Washington The publications of the Institution now number over 350 volumes, the subjects including Anatomy, Archeology, Astronomy, Botany, Chemistry, Economics and Sociology, Embryology, Experimental Evolution and Heredity, Engineering, Folk-Lore, Geology, History, International Law, Literature, Mathematics, Medicine, Nutrition, Philology, Physics, Zoology. Classified and descriptive lists will be sent postpaid on application. Year Book No. 17 for the year 1918. Octavo, xvi +331 pp., 1 pl., 3 figs. $1.00. 249. Part III. Barus, Carl. Displacement Interferometry by the Aid of Achromatic Fringes. Octavo. 100 pp., 73 figs. $1.50. Naval 259. Davenport, Charles B., and Mary F. Scudder. Officers: Their Heredity and Development. Octavo. iv+ 236 pp., 60 charts. $3.00. 260. Davis, Paul B., and COLLABORATORS. Studies on Solution in its Relation to Light-Absorption, Conductivity, Viscosity, and Hydrolysis: A Report upon a number of Experimental Investigations carried out in the Laboratory of the late Professor Harry C. Jones. Octavo, 144 pp., 26 figs. $2.00. 263. Tower, W. L. The Mechanism of Evolution in Leptinotarsa. Octavo, viii+1-340 pp., 19 pl, 156 figs. (Appendix.) Breitenbecher, J. K. The Relation of Water to the Behavior of the Potato Beetle in a Desert. Octavo, pp. 341-348, 5 figs. Not sold separately. $8.00. 264. Sturtevant, A. H. An Analysis of the Effects of Selection Octavo, 68 pp., 1 pl., 14 figs. $1.00. 265. Laughlin, Harry H. The Duration of the Several Mitotic Stages in the Dividing Root-tip Cells of the Common Onion. Octavo, 48 pp., 19 charts. $1.50. All communications should be addressed to CARNEGIE INSTITUTION OF WASHINGTON WASHINGTON, D. C. The Philippine Journal of Science ALVIN J. COX, M.A., Ph.D., General Editor 5811 Ellis Ave. Chicago, Illinois Bureau of Science MANILA, P. I. |