iv 



SCIENCE.— ADVERTISEMENTS. 



JDLIEN'S IMPROVED LAPIDARY LATHES 



For SLICING and POLISHING rocks, minerals, fossils, 

 etc., and for GRINDING DOWN the same into micro- 

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 tain COMPLETE APPARATUS for the work. Send for 

 illustrated catalogue. Rock sections for sale. 



GUSTAVUS D. JULIEN, 932 Bloomfield St.. HOBOKEN. N. J. 



Dr. HOWARD ADY, M.A., Ph.D., F.P.P.S.E., M.M.S., 

 Etc., presents his compliments to Scientific men in U.S.A., 

 and says that he will supply specimens of Kritish rocks and 

 rock-sections for microscope, with or without full p2tro- 

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 free. Exclmngcs of Britixli for A>n/rican Minerals and Rocks En- 

 couraged. Lessons by Correspondence in Lithology a Specialty. 



11 Aspenlea Road, Hammersmith, London, W., England. 



MARINE BIOLOGICAL LABORATORY 



Supply Department — 1. Zoologry — Preserved Material 



of all types of animals for class work or for the museum. 

 2. Botany— Preserved Material of Algae, Fungi, Liver- 

 worts and Mosses. For price lists and all information ad- 

 dress GEO. M. GRAY, Curator Woods HoU, Mass. 



"The Optical Instrument" 



(MONTHLY) 

 Just Sta-rttjcl 



Persons interested in Optical and other Scientific instru- 

 ments are invited to send for sample copy. 



E. P, Buffet, 108 Fulton St., N. Y. City 



Ninth Revised Edition. Published Jan. 1901,. 



The Microscope and Microscopical Methods 



By SIMON HENRY QAQB, of Cornell University. 



Important changes have been made aiid the chapter on 

 Projection Microscope rewritten and moie fully illustrated. 

 New figures of American microscopes and apparatus. 

 Postpaid $1.,50 as for the 8th edition 



COMSTOCK PUBLISHINQ CO., Ithaca, N. Y. 



Report of Committee on Standard Methods 



of Water Analysis 



to the Laboratory of the American Public Health 

 Association. 



Presented at the Havana Meeting, January 9, 1905. 



In cloth, 81.2,1 ; in paper, 81.00. 

 Copies may be purchased from 



The Journal of infectious Diseases, Chicago, Illinois 



The Journal of Experimental Medicine 



Edited by SIMON FLEXNER, M.D., and EUGENE L. OPIE, M.U. 



Published bimonthly under the auspices of the Rockefeller Institute for Medical Research, 

 New York. Subscription price, $5.00 per volume. 



THE MACMILLAIV COMFATSY, r»iil>lisliers, INew Yoi-k 



DUTY FREE 

 IMPORTATION 



We import scienttftc instruments free of duty for col- 

 leges and uni-versities from Societe Genevoise, Cam- 

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 Hartmann & Braun, Siemens & Halske, and many other sources. 



We shall endea-vor to secure your business on the basis of moderate prices and to 

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THE SCIENTIFIC SHOP albert b. porter 

 SCIENTIFIC INSTRUMENTS 322 Dearborn Street, CHICAGO 



...NEW AND IMPORTANT... 



APPARATUS FOR PHOTO-MICROGRAPHY BY MEANS OF THE ULTRA 

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The most important advance iu applied microscopy since the advent of (he Oil Imuiorsion Objective. 

 Specimens require no staining. Price-list and reprint of descriptive and ilhistraicd arlicle in •• Zeitschrift 

 fur Wissenschaftliche Mikroskopie," sent upon request. 



ARTHUR H. THOMAS COMPANY, importers and Dealers 



Microscopes and Laboratory Apparatus 



12th & Walnut Sts., 



PHILADELPHIA 



