Marine Biological Laboratory Woods Hole, Mass. INVESTIGATION Entire Year INSTRUCTION une 29 to August 9 1921 SUPPLY DEPARTMENT Open the Entire Year Facilities for research in Zoology, Embryology, Physiology, and Botany. Eighty-four 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, $75. A lecture course on the Philosophical Aspects of Biology and Allied Sciences is also offered. Animals and plants, preserved, living, 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 slides in 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. Yale University SCHOOL OF MEDICINE Affiliated with the New Haven Hospital and New Haven Dispensary 109th Session Reorganized on a full-time basis Entrance Requirements: A minimum of two years (or its equivalent) of college including general biology, physics, general and organic chemistry, physical chemistry or laboratory physics, and either French or German. ALL OF THE GENERAL FACILITIES As the number admitted to each class is limited, applications must be made before June 15. Dean, Yale University School of Medicine NEW HAVEN, CONN. Our Laboratory Spectrometers Are sold in competition with instruments of European make to many of the best laboratories throughout the world. WM. GAERTNER AND CO. Physical and Astronomical Instruments 5345-49 Lake Park Avenue CHICAGO CADMIUM STANDARD CELLS For use with potentiometers, electrometers, and ballistic galvanemeters, or wherever else a precision standard of electromotive force is needed. Negligible Temperature Coefficient. Contents hermetically sealed in glass so that lowering of electromotive force due to evaporation is impossible. Mounted in moulded box, or unmounted. My comparison certificate accompanies each cell without charge. On November 13, 1916, three normal cadmium cells made by me were certified by the Bureau of Standards as differing from their group of reference cells by less than one part in one hundred thousand, all three having the same value. On March 30 1920, after the lapse of three years and four months, the same three cells were again compared by the Bureau of Standards. The maximum difference among the three was less than one part per hundred thousand, and the maximum difference from their certified value of 1916, was less than one part per hundred thousand. In other words, these cells showed a degree of constancy to all intents equal to that considered most highly satisfactory, if not remarkable, in the very best type of precision resistance standards. (see Bul. Bur. of Stand. Vol. 5, No. 3. p. 427.) The cells in question were in nowise special. They were made of the materials regularly prepared by me, and were set up with no greater care than that constantly employed in the making of my standards. Marion Eppley, (A.M., Ph.D.) Physico-Chemical Apparatus. No Laboratory Equipment is complete without some variable resistances. To maintain the high standard of your outfit we suggest the addition of some "Becbro" Sliding Contact Rheostats (Tubular and Stone Types) Thousands of these rheostats have been manufactured and sold by us (the original American Manufacturers) to most all Universities, Colleges, Technical Schools and Industrial Concerns and have always given entire satisfaction. Write for Bulletin C-5 BECK BROS. 3640-42 North Second Street Philadelphia, Pa. 268. Student's Model Analytical Balance. This is an analytical balance of simplified design, of full size; the material, the workmanship and the finish of this balance are the same as the more expensive balances. Case-Solid mahogany, finished and rubbed; 17" wide, 16" high, 9" deep, counterpoised door. Dial-Graduations are red on white background so that black pointer is easily observed. This balance has a brass column, a circular universal level, a double rider carrier, adjustable leveling feet and a pan arrest independent of the beam release. Price, $65.00 SCIENTIFIC MATERIALS COMPANY Everything for the Laboratory' PITTSBURGH, PA. NEW SERIES VOL. LIII, No. 1373 FRIDAY, APRIL 22, 1921 SINGLE COPIES, 15 CTS. Headquarters for Assay, Bacteriological and Cher tory Apparatus Also for Chemical Reagents, Minerals, Drugs Amongst our leading a we mention the following and Student Balances; Dulin forms of asphalt testing s; U. S. Weather Bureau Barometer erson and Parr Calorimeters with accessories; Campbell, Hurley, Du-Bosc, and Kober Colorimeters, also Lovibond Tintometers; Braun Chipmunk Crushers and Disc Pulverizers; Barnstead and Stokes Water Distilling Apparatus; Juerst Ebuloscopes; Braun and Kimley Electro Analysis Apparatus; Bailey, Pickel and Soxhlet Extraction Apparatus; Replaceable Unit Organic, Combustion, Muffle, Crucible, "HeviDuty" and " High-Temp" Electric Furnaces; Orsat, Hempel, Elliott, Haldane, Henderson, Rogers, Tuttle, and Williams Gas Analysis Apparatus; Detroit Gasoline Gas Generators; Gauges; Beamué, Brix Specific Gravity, and Twaddle Hydrometers; Bausch & Lomb and Spencer Microscopes and Microtomes; Bausch & Lomb Metallurgical Outfits, also Wysor Grinding and Polishing Machines; Hortvet Cryoscope and Morgan Drop Weight Apparatus; DuPont Nitrometers and Kjeldahl Apparatus; Abel Pensky and Pensky Martin Flash Point Testers; Doolittle, Engler, MacMichael, Sayboldt and Stormer Viscosimeters; Bingham and Green Viscometer and Plastometer; Freas Automatically Controlled Electrically Heated Incubators, Ovens, Sterilizers, Water Baths and Water Thermostats, Eppley Standard Cells, Oil Thermostat and Electric Titration Apparatus, Polariscopes; Filter Presses, Vacuum and Pressure Pumps, Refractometers, Spectroscopes, Shaking Apparatus; Stirring Apparatus; Thermometers, Water Testing Apparatus, etc. Du Boise Colorimeter |