NEW this fall . . . a

BIOCHEMICAL PREPARATIONS, Volume 11Editor-in-Chief, ERIC G. BALL, Harvard Medical School. Prepared and edited by

outstanding biochemists, the second volume of this valuable series presents accurate, de-tailed, reproducible methods for the preparation of 23 substances used in biochemicalresearch. The following information is provided about each compound: principle, start-ing material, procedure, properties, purity of product, and method of preparation. All thepreparations can be effected with easily available, inexpensive materials. Emphasis is onisolation but pertinent preparations are also provided. 1952. 109 pages. $3.00.

ESSENTIALS of MICROWAVESBy ROBERT B. MUCHMORE, Member of the Technical Staff, Research and

Development Laboratories, Hughes Aircraft Company. This book gives the beginner thefacts he needs to utilize this valuable tool. Written to be understood without mathematics,by anyone with elementary training in physics or engineering, Essentials of Microwavesuses word pictures rather than abstruse concepts to explain microwave phenomena andapparatus and backs them up with illustrations wherever possible. Among the features:the book gives the fundamental empirical laws of electricity and magnetism and showshow by combination and extension these laws govern all microwave phenomena; appliesthe rules governing wave propagation and reflection to the understanding of wave guides,cavity resonators, etc.; treats the special problem of guided wave transmission, introducingthe concept of characteristic waves or modes. Approx. 242 pages. Prob. $4.50. Readythis month.

An Introduction to the CHEMISTRY of the HYDRIDESBy DALLAS T. HURD, Research Associate, General Electric Company. In this

book you'll find vital, stimulating information on new and interesting developments in thechemistry and application of hydrides. The author presents the complete hydride storyfrom preparation, physical and chemical properties, chemical reactions, industrial andiresearch applications, and toxicology, to techniques for handling hydrides and hydridecompounds. A general interpretation of the theory of chemical bonding of the elementhydrogen is presented, with particular reference to hydride systems. All the chemicalelements known to form compounds with hydrogen are discussed and a list of com-mercial sources of specific hydrides is provided. This is not a mere "catch-all" referencebut a critical, coordinated presentation of the theory, properties and reactions of hydrides.1952. 231 pages. $5.50.

The MOLECULAR ARCHITECTURE of PLANT CELL WALLSBy R. D. PRESTON, D.Sc., F. Inst.P., Reader in Plant Biophysics, University of

Leeds. The theme of this book centers around the extraordinary advances which havebeen made during the past 25 years, in the understanding of the molecular structure ofthe solid envelope which surrounds every plant cell. The first few chapters present aresume of the more important physical and chemical approaches to cellulose structure.with an explanation of the anatomy and development of the tissues under discussion.The detailed structure of cell walls in a wide variety of plants-is the meat of the book.Much of the material is the result of work performed by the author in his own labora-tory or in the laboratory of his associates. In Press. Approx. 224 pages. Prob. $6.75.

Order your on-approval copies today.

JOHN WILEY & SONS, Inc., 440 Fourth Ave., New York 16, N. Y.September 12, 1952 11

APPLICATION FOR HOTEL RESERVATIONS119th AAAS MEETING

St. Louis, Mo., December 26-31, 1952The list of hotels and their rates and the reservation coupon below are for your convenience in

making your hotel room reservation in St. Louis. Please send your application, not to any hoteldirectly, but to the AAAS Housing Bureau in St. Louis and thereby avoid delay and confusion. Theexperienced Housing Bureau will make assignments promptly; a confirmation will be sent you intwo weeks or less. Share a room with a colleague IL-you wish to keep down expenses. Mail your ap-plication now to secure your first choice of desired accommodations. All requests for reservations mustgive a definite date and estimated hour of arrival, as well as date and approximate hour of departure.

HOTELS AND RATES PER DAYHotel* Single Double Bed Twin Beds Suites

CHASE 6.00- 9.00 8.00-10.00 8.00-12.00 14.00-30.00DESOTO*D 4.00- 6.00 6.00- 9.00 7.50-14.00 11.50-22.00JEFFERSON*D 4.50- 8.50 7.50-11.00 8.50-11.50 19.00-30.00LENNOX D 5.00- 7.00 6.50- 9.00 8.50- 9.50 13.00 & upMAJESTIC D 3.25- 4.50 5.25- 6.25 7.00- 8.00 10.00-15.00MARK TWAIN D 4.50- 6.50 6.00- 8.50 8.50- 9.50 16.00 & upMAYFAIR D 4.00- 7.00 5.50- 8.00 8.00-12.00 15.00 & upMELBOURNE 4.50- 8.00 .. 6.50- 8.50 8.50-11.00 17.00-25.00ROOSEVELT Reserved for mathematicians, $2.75 to $3.75 per bed.SHERATON 5.25- 8.85 8.00-11.00 9.00-12.50 11.00-30.00STATLER*D 4.00- 7.00 6.50- 9.50 7.50-11.00 21.50-26.50

* Hotels starred have sessions in their public rooms. For a list of the headquarters of each participating society and section,please see Association Affairs, Science, July 25, or The Scientific Monthly, August.D = downtown hotel; the other hotels (not downtown) are for the mathematicians primarily.

. THIS IS YOUR HOTEL RESERVATION COUPON. -AAAS Housing BureauRoom 406-911 Locust St. Date of Application ............................St. Louis 1, Mo.Please reserve the following accommodations for the 119th Meeting of the AAAS in St. Louis, Dec. 26-31, 1952:

TYPE OF ACCOMMODATION DESIREDSingle Room ............ Desired Rate .........mMaximum Rate.Double-Bedded Room. Desired Rate ......... Maximum Rate ........ Number in party ..........Twin-Bedded Room ...... Desired Rate ......... Maximum Rate.Suite .................... Desired Rate ......... Maximum Rate ........ Sharing this room will be:(Attach list if this space is insufficient. The name and address of each person, including yourself, must be listed.)

First Choice Hotel .............Second Choice Hotel.............Thi rdChoice Hotel .

DATE OF ARRIVAL .DEPARTURE DATE.(These must be indicated-add approximate hour, a.m. or p.m.)

NAME ..................i i.......esi.....................................ieae'prin ortype).......................(Individual requesting reservation) (Please print or type)

ADDRESS .....................................................................(Street) (City auf Zone) (State)

Mail this now to the Housing Bureau. Rooms will be assigned and confirmed in order of receipt of reservation.

12 SCIENCIE, Vol. 116

Above: Close-up of the con- Accuracy ... day in and day outversion table in millimeters, 'oround the clock dependability ..,. that'smillibars and inches. what you get in a Cenco MercurialLeft: Cenco Mercurial Ba-.aoee.Cnofetrs..ptnerometer with white lac- aoee.Cnofaue..ptnequered metal mounting. improvements precision manufac-

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of unusual qualty at a remarkably low price.These instruments are built with the tube completely enclosedin hexagonal brass tubing to which the metric and Englishscales are attached. Patented construction of the mercury wellpermits fine adjustment and its transparent glass wall admitsplenty of light for good visibility.Cenco Mercurial Barometers are constructed as prescribed bythe U. S. Weather Bureau and conform to correction chartsestablished by the Bureau.

Order today for prompt deliveryNo. 76890 Cenco Mercurial Barometer for altitudes 0 to 4000 ft.with scales ranging from 600 to 800 mm and 24.5 to 31.5 inches-.

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No. 76891 Cenco Mercurial Barometer, same as No. 76890 butfor altitudes from 1500 up to 10,000 feet. Scale ranges from500 to 700 mm and 19.5 to 27.5 inches. Each .........$ 5No. 76892 Barometer Mounting made of sheet metal for safe and convenientmounting of Cenco barometers. Finished in white lacquer to providea light background for adjusting the zero index and vernier. With $conversion table. Length, 37Y inches, width 3V inches. Each.. . 7 5

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September 12, 1952

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POSITIONS WANTEDBiochemist: Ph.D. Married, 30. Excellent background in nutri-tion. Research experience in fractionation and isolation techniques.Instrumental analysis, physiology, microbiology. Two years' in-dustry. Publications. Desires academic or industrial position, re-search opportunities. Box 287, SCIENCE. X

Biochemist-Enzymologist, Ph.D., 33, Canadian, family. Sevenyears research experience in microbial metabolism, bacterial varia-tion and enzyme f6rmation. Two years teaching. Strong backgroundOrganiic Chemistry and Genetics. Languages. Available January1953. Desires position in industrial research or development. Box283, SCIENCE. 9/12

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Plant Physiologist-Microbiologist; Ph.D., 28. Research experiencein photosynthesis, growth regulation, nitrate reduction, and algalphysiology. Industrial or teaching position with research oppor-tunities desired. Box 288, SCIENCE. X

Positions Wanted:(a) Bacteriologist; M.S., considerable work toward Ph.D.; twelveyears research, scientist large industrial company. (b) Chemist;Ph.D. (Major: Plant Biochemistry; Minor: Physical Chemistry) ;three years, control chemist, eight years, research chemist in in-dustry; four years, director, food processing organization. Forfurther information, please write Science Division, Medical Bureau,Burneice Larson, Palmolive Building, Chicago. X

Research Scientist: B.Sc. and M.Sc. seeking opportunity Bacteriol-ogy, Chemistry, Engineering and Science. In 30's, single, willingto travel, hard worker, organizer gets along with people. Success-ful record. Box 260 SCIENCE. X

Zoologist, man, 38, family, Ph.D., Entomology, Invertebrate Zool-ogy. Five years' university teaching. Publications. Desires teaching-research position. Box 285, SCIENCE. X

Zoologist; M.S., single, age 25. Two years university assistant inZoology. lDesires position teaching general Zoology in Westernor Northwestern school. Box 286, SCIENCE. X

|llliiiilllliiiliiillllillPOSITIONS OE lil||U|||||||||||||||Biochemist: Recent Ph.D. preferred. Excellent opportunity forcareer man interested in basic research. Carries academic appoint-ment; may involve some teaching after first year. Newly equippedlaboratory. Please send personal and professional data. Kresge EyeInstitute, 690 Mullett Street, Detroit 25, Michigan. 9/19

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9/12, 9/19

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SCIENCE, Vol. 116

YOUR ad here reaches over 32,000 foremost scientistsin the leading educational institutions, industriallaboratories, and research foundations in the U. S.and 76 foreign countries-at a very low cost

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