IA strong,human approachto zoology

Reviewsmodern theoryand practice

Describesmoderninsecticidesand equipment

Surveys basicrelationshipsbetween soilsand plants

MAN AND THE ANIMAL WORLDBy BERNAL R. WEIMER, Bethany College. This book treats the organismsof the living world as dynamic, living entities, manifesting in various waysthe fundamental life phenomena common to all living animals. It beginswith a study of man as an introduction to the life principles and processesof other animals. Includes a modern treatment of vitamins and hormones.May 1951. 569 pages. $5.00.

OPTICAL CRYSTALLOGRAPHYSecond Edition, by ERNEST E. WAHLSTROM, University of Colorado. A com-pletely modernized book treating in great detail the principles of opticalcrystallographic theory. Emphasis is on the immersion method of determiningoptical properties of crystals and fragments. Gives a thorough explanationof the construction and manipulation of polarizing microscopes and acces-sories. 1951. 247 pages. $4.50.

INSECT CONTROL BY CHEMICALSBy A. W. A. BROWN, University of Western Ontario. Presents the essentialfacts and theories on the chemical, physical, and toxicological aspects of in-secticides, relating their molecular structure to toxicity. The author evaluatesthe hazards of these insecticides to plants and animals by examining theireffects on the balance of nature and discussing the question of insecticide-resistant strains of insects. June 1951. Approx. 790 pages. Prob. $8.00.

FUNDAMENTALS OF SOIL SCIENCESecond Edition, by C. E. MILLAR and L. M. TURK, both at Michigan StateCollege. General principles of soil science are emphasized and explained insimple terms. Special attention is given to recent developments in the field.Presents interesting, up-to-date facts on soil development, physical andchemical properties of soils, soil moisture, fertilizers, irrigation, soil conserva-tion, etc. August 1951. Approx. 432 pages. Prob. $5.00.

DIFFERENTIAL EQUATIONSRevised Third Edition, by H. B. PHILLIPS,

I The Massachusetts Institute of Technology.I 1951. 149 pages. $3.00.

RADIOACTIVITY APPLIEDI TO CHEMISTRYI Edited by ARTHUR C. WAHL and NORMANI A. BONNER, both at Washington University.I June 1951. Approx. 666 pages. Prob. $7.50.

An Introduction tothe CHEMISTRY OF THE SILICONESSecond Edition, by EUGENE G. ROCHOW,Harvard University. July 1951. Approx. 210pages. Prob. $5.00.

PHYSICAL BIOCHEMISTRYSecond Edition, by HENRY B. BULL, North-western University Medical School. AugustApprox. 351 pages. Prob. $S5.50.

ARTIFICIAL FIBRESBy R. W. MONCRIEFF, B.Sc., F.R.I.C., F.T.I.1951. 313 pages. $4.50.

Send for copies on approval

JOHN WILEY SONS, INC. 440 Fourth Avenue New York 16, N. Y.May 18, 1951 13

FS MULTI-LAYERINTERFERENCE FILMS

Dichroic & Achromatic Beam Splitters

hC

IC_ I.,

LO. _ z

0. bo9K 0=

WITE UGHT

Chromatic SpectralSelection Effect; acertain portion of thespectrum is reflected,the remainder trans-mitted.

YELLOW RAYS

Achromatic Spectral Selection Effect; the incident light issplit into two beams, one reflected, one transmitted, eachbeam retaining the spectral properties of the original inci-dent beam.Transmission or reflection peaks as high as 85 to 9070but the spectral bands are relatively broad.Submit your problems and ask for bulletin MI-318giving graphs of standard types now available.

FISH-SCHURMAN CORPORATION230 East 45th Street, New York 17, N. Y.

Fish-SchuIrmV

SCIENCE, Vol. 113

KLETTELECTROPHORESIS

CUSTOM MADE

TOOL FOR THE ANALYSISOF COMPLEX COLLOID SYSTEMS, AND FORTHE CONTROL OF -PRODUCTION OFPURIFIED PROTEINS, ENZYMES, HORMONES

KLETT MANUFACTURING CO.179 EAST 87TH STREETNEW YORK, N. Y.

STREET

CITY STATF

1. >.V)IxwD-jCD

..e

14

BOTANY. A Textbook for CollegesBy J. BEN HILL, Pennsylvania State College; LEE 0. OVERHOLTS, and HENRY W. POPP,Pennsylvania State College. McGraw-Hill Publicationts in the Botanical Sciences. Second edi-tion, 695 pages, $5.50

This well known book has been carefully revised in order to record recent advances in the fieldand to improve the teachability of the text. The present edition covers advances in the field suchas photosynthesis, respiration, fermentation and enzymes, metabolism, hormones and vitamins,etc. New sections have been added on viruses, actinomyeetes, diatoms, etc.

PHYSIOLOGY OF THE FUNGIBy VIRGIL G. LILLY, West Virginia University, and HORACE L. BARNETT, West VirginiaUniversity. McGraw-Hill Publications in the Botanical Sciences. Ready in July

A discussion of living fungi, their life processes and the factors which influence their activities.This is the first book of its kind designed to accumulate and coordinate the present informationon the physiological aspects of growth, methods of eultivating fungi, reproduction, parasitismand variation.

THE CONSERVATION OF GROUND WATER. A Survey of the Present Ground-WaterSituation in the United States

By HAROLD E. THOMAS, U. S. Geological Survey. Ready in JuneThe first book of its kind to be published in the United States, this text surveys the natural con-ditions determining the occurrence of ground water and describes the history and effects ofground-water used throughout the country. Sponsored by the Conservation Foundation to helpdefine the present situation, and to suggest courses of action, this book reviews over 70 areaswhere ground-water has been investigated.

LIQUID EXTRACTIONBy ROBERT E. TREYBAL, New York University. McGraw-Hill Chemical Engineering Series.422 pages, $7.50

A complete review and organization of the subject matter of liquid extraction providing an ex-tended coverage of the subject. Unique in the field, this text is characterized by its comprehen-sive treatment, correlation of apparently unrelated data, and detailed references to originalsources of information.

Send for copies on approval

BOOK COMPANY, Ic.

MIay 18, 1951

McGRAW- ILL

Eggpon 11 mjmwm. millill 3 11 IIIIIIIIIIII III, III m ILi Eggm 11111 sIg lill

s a a 2 0 s m Aft IV& lowm lial Ia

%I MEN-2 9 li v 2

15

,OO600K~0

RESPIRATORY ENZYMESprepared by the Biochemists of theUniversity of Wisconsin

Each Chapter is Written by a Specialist.

This book covers a wide scope of interest butwill be of particular import to:

Graduate Classes in enzymes and intermediarymetabolism

Students for use as reference material

Clinicians and Pharmacologists for interpretingenzyme drug interrelationships

Anyone interested in the fundamental aspectsof Biochemistry

PRICE $4.50Send for an On-Approval Copy

d~~~~S'*S

DEPENDENCY.e. . or failureNo one factor has a more important role in theachievement of conclusive results in laboratory re-search, than the reagent used. Carworth Farms be-lieves that the laboratory reagents it produces willgive equal or more satisfactory results than any otheryou may use.

We offer the continually increasing demand for theseproducts as evidence of this fact.

"VACSEAL" Guinea Pig Complement3cc 7ec 20cc

Anti-sheep HEMOLYSIN (with glycerin)2cc 5cc 10cc

Guinea Pig ANTIGEN2cc 5cc 10cc

Sheep Cells (in citrate or mod. Alsever's)15cc 30cc 60cc (or larger)

Sterile Citrated Rabbit Blood15cc 30cc 60ce

For further information please write to:

CARWORTH FARMS, INC., NEW CITY, NEW YORK

For MEASUREMENT of SKIN RESISTANCEGarceau RECORDING

PSYCHOGALVANOMETERFor the study of thepsychogalvanic reflex

and skin resistance.

The instrument isdirect-reading and givesa written record of thereaction of the patient.Price $775.00

GarceanuCLINICAL DERMOHMETER

For clinical and experimen- >tal investigation of disordersinvolving sympathetic reac-tion, such as pain reflexes.In the psychological labora-tory, the instrument has awell-known application as aso-called "lie detector". Re-sistance is read directly froma calibrated dial. Small vari-ations, greatly magnified, areshown on the meter. Batteryoperated. Price ... $115.00

ELECTRO-MEDICAL LABORATORY, INC.New Address-SOUTH WOODSTOCK, VERMONT, U.SA.Pioneer manufacturers of the electroencephalograph

SCIENCE, Vol. 113

PHOTOVOLTLine-Operated ElectronicMULTIPLIER-PHOTOMETER

Mod. 520-M

For the exact measurementof extremely low light valuesdown to 1/10,000 microlumen.

Write for Bulletin #360 to

PHOTOVOLT CORP.95 Madison Ave. New York 16, N. Y.

I

16

|2 Attinutiec %/cwndar iextt

This well-known text has been thoroughlyrevised and contains 300 new illustrations

College Zoology, 6th EditionROBERT HEGNERLate Professor Protozoology, Johns Hopkins UniversityKARL STILESProfessor Zoology, Michigan State CollegeDr. Stiles has made the sections on physiology and genetics superiorto the treatment of these subjects in other texts. The half-tonesand line cuts which constitute the new illustrative material have,for the most part, been drawn from dissected animals by one of thebest zoological artists in the U. S. New material has been addedon experimental embryology, selected references are found at theend of all chapters, and there is more emphasis on ecology, geo-graphical distribution, natural history, parasitology, and the sci-entific method. Coming in June

Important, up-to-date material presented in a

revision that embraces many new areas of science

Bacteriology, 5th EditionROBERT BUCHANANResearch Prof., Emeritus Prof. Bacteriology, Dean Graduate School,Director Iowa Agricultural Experiment Station, Iowa State College.ESTELLE BUCHANANProfessor Bacteriology, Iowa State CollegeThe text of this well-known book has been rewritten to include avast amount of new and important material. The authors havetreated an exceedingly complex subject with simple, readable lan-guage and the student is given concrete ideas of the usefulness ofbacteriology in many new fields. The number and the quality of theillustrations has been improved and there is more satisfactory han-dling of classification and differentiation of the organisms. Thecentral plan of organization remains the same. Coming in May

TH E MACM I LLAN C OM PA N Y_IG_.6L Li I

I

May 18, 1951 17

TH-E SPOT GALVANOMETERLaboratory Accuracy . . . Shop Ruggedness

The Cambridge Spot Galvanometer provides a completeoutfit-galvanometer, lamp and scale-in one self-con-tained metal case. It is robust, has a stable zero and doesnot require accurate levelling. The sharply defined spotcan easily be read at a distance. The lamp may be oper-ated on A.C. service current or 4-volt battery. Sensitivityin mm. on scale is from 19 to 170 per micro-ampere usingcoils of 10, 40 and 700 ohms. Scale can be read to 0.2mm. Send for Bulletin 167-S.

CAMBRIDGE INSTRUMENT CO., INC.3748 Grand Central Terminal, New York 17, N. Y.

PIONEER MANUFACT{IRERS OF PRECISION INSTRUMENTS

NO NEED TO REWIRE YOUR LAORATORY!With rotating Immediate

manometer stand , delivery

Simple Design -Substantial ConstructionSend for data on Warburg glassware, refrigeratedWarburg, electroencephalographic equipment

G M E *.4 Franklin Avenue * Madison, Wisconsin

COMPARE THE EDGES. Photomicrograph(a) shows a microtome knife edge shar-pened by the Berkeley sharpener. Noteits even smoothness, assurance of bettersections. Photomicrograph (b) shows ablade laboriously hand sharpened, honedand stropped, but note the nicks andserrations still remaining.

COMPARE THE TIME. In tests, wherever made, and in prac-tiGC in hundreds of laboratories, the Berkeley MicrotomcKnifc Sharpencr gives perfect edges in one-third th: timcrequired for hand honing and stropping.

Let us send you Bulletin MKS-12 giving full informationabout this indispensable laboratory aid.

I3e~he/eCsc4beko

* Write for Descriptive Brochure

BERKELEY CHROMATOGRAPHY DIV.UNIVERSITY APPARATUS COMPANY

Dept. H 0 2229 McGee Avinue * Berkeley 3, Calif.

SCIENCE, VoL 113

A New Mosby Book!

3ntroduction to

Modern Chemistry

This text was written over a period of aboutthree years, and tested in the classroom aswritten, in order to provide students with thematerial they need for a first year course in gen-eral chemistry. Because it was intended that thestudent should use the text as a study aid ratherthan a reference book, the authors omittedmuch that was considered unnecessary detail orof purely historical interest. Likewise theyavoided presenting material that they on thebasis of more than forty years' combined teach-ing experience felt belongs in an advancedcourse.

The plan of the first two-thirds of the bookis in close accord with present trends in teach-ing practice, although atomic structure is in-troduced somewhat earlier than discussions ofchemical behavior which follows.

The greater part of the last third of the bookis devoted to the metals which are discussed,not in the usual fashion, by families, but in theorder in which they are met in a typical schemeof qualitative analysis for cations.

By P. C. GAINES, Professor of Chemistry; LAURENCE 0.BINDER, JR., Associate Professor of Chemistry; and RAYWOODRIFF, Association Professor of Chemistry-all of Mon-tana State College.

576 Pages, 92 Illustrations, Price $4.75

The C. V. MOSBY COMPANY3207 Washington BoulevardSt. Louis 3, Missouri

Please send meGAINES-BINDER-WOODRIFF Introduction to Modern Chemistry ..... .................. $4.75

E] Enclosed find check E1 Charge my account

Name ...............................................................................

Address .............................................................................

May 18, 1951 19

C When Accuracy is Important-!wes>y;ys -r-t T.7.7 ''''' -''THE CASTLE PRECISION INCUBATOR is de-

signed and built to give you the precise ac-

curacy that is essential in bacteriologi.alwork. Construction is of monel metal forlifetime use.

Independent laboratory tests proved these

two important facts:

UNIFORMITY: %°C. Never as much as adegree variation between top and bottom ofchamber even when loaded.

CONSTANT TEMPERATURE: A 1/20 to 1/40C.Never more than a fraction of a degree varia-tion at the thermometer ... despite roomtemperature fluctuations from 100 to 35°C.

v-;-fX-* -V ; 00fyp; t; -XV-:; S Xt00;000;170;Forfulldetailswrite: Wilmot Castle Co.,1212 University Ave., Rochester 7, N. Y

L~~ J~~ BacteriologicalApparatus

"Belongs on the 'must'

list of scientistsNE MIR KILU NA Oand clinicians in Using Zirconium Arc Lamp

the fieldof child for MICRO-PROJECTION.~for PHOTO-MICROGRAPHY

Kidevelopment."-Science

ERIKH. ERIKSON

CHILDHOOD AND SOCIETY ~~~~~~~~~MikrarkIllumninators provide intense, cool

AND point source of light ~~~~through the use of the newCombining the insights of clinical psycho- 100 watt Zirconium bulb.This steady light source

is ideal for microscopy and photo-micrography.analysis with a new approach to cultural It is the correct color temperature for full coloranthropology, this important new book re- pictures. MODEL C-100 with improved coolinglates the anxieties of childhood to the up- syste illustrated.

Write for further details or demonstration toheavals of society'. "A major contribution tothe much needed synthesis of the social and .1. .1biological sciences."-The Survey J

At all bookstores * $4.7S5 15W.AWNOTONall bOokstoreslol Fift8 38 Broadway, N.Y.C. AL. 4-3510

W. W. NORTON & (0., 101 Fifth Ave., N. Y. 3 -*10 antSre,Piaepi

May 18, 1951 21

PERISONNEL PLACEMENTBotanist: Ph.D. Eight years University teaching experience inBiological Sciences. Mycology, General Botany, Bacteriology.Publications. Desires teaching position with opportunity for re-search. Male. Age 33. Married. Box 511, SCIENCE. X

Botanist, B.S., M.S.: Teaching, administrative, business experi-ence (industry, schools elementary through college) in biology,botany, gardening, horticulture, wishes new connection with uni-versity, college, institution, or industry. Experienced in research,writing, speaking, educational and sales promotion. Box 514,SCIENCE. X

Pharmacologist: Veterinarian, 3Y2 years experience in industrialresearch, 2 years graduate work, teaching experience, publications.Seek position in Northeastern states. Will consider technicalwriting, applied pharmacodynamics or veterinary position. Box510, SCIENCE. X

Pharmacologist: Ph.D. Age 28. Experience tracers, enzyme meth-ods; familiar with histochemical techniques. Prefer academic orinstitutional research. Box 515, SCIENCE. X

Physical Chemist: Ph.D.; three years' teaching (Chemistry);two years, chief chemist in industry; five years, chief physicist,large industrial company; particularly interested research, newproduct deveolpment; for further information, please write ScienceDivision, Medical Bureau (Burneice Larson, Director), PalmoliveBuilding, Chicago. X

Physiologist-Biochemist: Ph.D. Age 31. Academic or research in-stitution desired. Six years teaching. Varied research. Publica-tions. Competent animal surgeon. Box 512, SCIENCE. X

SkiUed linguist: gymnasia-trained in science, American B.A.,competent sn German Russian, French, Italian and Estonian.Olga Moldenke, 410 S. Pickard, Norman, Oklahoma. X

Zoologist, Ph.D., eleven years teaching experience in ComparativeAnatomy, Histology, Embryology, Invertebrate and General Biol-ogy. Available June or September. Box 516, SCIENCE. X

111111111111111111111011POSITIONS OPEN HS!IIIIIIIIIIIIIIIIS

Positions Open:(a) Research Pharmacologist; large industrial company; Chicagoarea. (b) Physician with writing ability to edit well known jour-nal; East. (c) Scientist trained in bacteriololgy, chemistry andendocrinology, to direct research, department of obstetrics-gynecology, university medical school; $5,000-$6,000. (d) Physi-ologist and Biophysicist, supervisory appointments; should bequalified to direct research programs involving effects of radia-tion on endocrines; Ph.D.'s required; medical degrees advanta-geous; West. (e) Metallurgist or Physical Chemist experiencedin gas plating, food chemist and bacteriologist with fermentationpilot plant experience; research and development organization;expansion program. (f) Bacteriologist (PH.D.) or Zoologist(PH.D.); department of biological sciences, one of leading uni-versities, Midwest. (g) Chemist or chemical engineer with in-dustrial research experience leaning toward inorganic and physicalchemistry; challenging opportunity in industry; New England.S5-3, Science Division, Medical Bureau (Burneice Larson, Di-rector), Palmolive Building, Chicago. X

-The MARKET PLACEBOOKS * SERVICES * SUPPLIES * EQUIPMENT

BOOKS

WANTED TO PURCHASE . . . Sets and runs, foreignt' PmrLUTurEP PERIODICALS and domestic. EntireSCIENTIrFI and BOOKS J collections wanted.WALTER 1. jOHNSON * 125 East 23rd St., New York 10. N. Y.

OFFERED: Kongresszentralblatt f.d. Gesamte Innere Medizin& Grenzgebiete. Springer. 1928-1936, vol. 50-83, complete, bound,perfect condition, $165.00. BOX 513, SCIENCE. X

SCIENTIFIC BOOKS and PERIODICALS WANTEDComplete libraries-Sets and runs-Single titles

Also, please send us your want lists.STECHERT-HAFNER, IN31 East 10th St., New York 3

BACK NUMBER PERIODICALS -Bought and SoldTell us what you want!-What have you to offer?

Abrahams Magazine Service K DEPT. P, 56 E. 13th ST.Established 1889 NEW YORK 3. N. Y.

Your sets and files of scientific journalsare needed by our library and institutional customers. Please sdus lists and descri.ption of periodical files you are willing to sellat high market pnces. Write Dept. A3S, J. S. CANNER, INC.

Boston 19, Massachusetts

SCIENCE, Vol. 113

YOU reach over 32,000 scientists inthese columns at a very low cost

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

CLASSIFIED: 20f per word, minimum charge $5.00. Use ofBox Number counts as 10 additional words. Correctpayment to SCIENCE must accompany ad.

DISPLAY: Rates listed below-no charge for Box Number.Monthly invoices will be sent on a charge account basis

-providing satisfactory credit is established.Single insertion $17.50 per Inch

7 times In 1 year 16.00 per Inch13 times in 1 year 14.00 per Inch26 times In 1 year 12.50 per inch52 times In 1 year 11.00 per inch

For PROOFS on display ads, copy must reach SCIENCE 4weeks before date of issue (Friday of every week).

DIRECTOR OF PHARMACOLOGYand CHEMOTHERAPY

of industrial research organization in metropolitanN. Y. M.D. or Ph.D. in Pharmacology, Physiology,or Biology with teaching or industrial experienceand proven ability to direct Biological researchprogram. Competent Scientific Staff, TechnicalAssistants, and modern well-equipped Labs.

Write giving details, training, experience andsalary desired, to

Box 506, SCIENCE

AnnouneingTHE CULTURING OF ALGAE: a symposiumPhycological Society of America* Seven papers on culture techniques, and the use of algalcultures in medical, biological and economic research. Ap-pendix on culture media. Bibliography. 114 pp., Illustrated,1950. Price: $2.25 postpaid.

Published by CHAS. F. KETTERING FOUNDATIONFar Hills Branch Post Office, Dayton 9, Ohio

SCIENTISTS-salaried positions, $3,600 to $25,000.This confidential service for outstanding men who desire a changeof connection, will develop and conduct preliminary negotiationswithout risk to present position. Send name and address for details.TOMSETT ASSOCIATES * 1205 Berger Bldg., Pittsburgh 19, Pa.

14

22

IThe MARKET PLACE-BOOKS * SERVICES * SUPPLIES * EQUIPMENT

RELIABLEtandDISCRIMINA TINGSER VICEto Colleges and Universities ofthe Nation and their PersonneL

MEMBER N A T AJackson Blvd., Chicago 4, Illinois

AMERICANCOLLEGE

2n E Jacksou DlviChicag 4, ID.

Universities and Colleges throughoutthe United States continue theirgreat demand for recommendationsfor those trained in the differentfields of Science. The positionsrange from instructorships to headsof departments.

c

Our service is nation-wfide.

ULTRAPURE MERCURYMercury purified to an impurity level of' less than0.00001% is available at reasonable cost for yourplant or laboratory. Ideal for use in McLeod gauges,diffusion pumps, thermometers, barometers, mercurycontact switches, standard cells, polarographs and anyapparatus requiring completely uncontaminated mer-cury surfaces.Mercury is shipped in Pyrex glass stoppered bottlesto ensure highest quality; it is ready for instant use.

Descriptive bulletin and price schedule on request.

EDWARD SHAPIRO - P.O. Box 302, Swarthmore, Pa.

White SWISS Mice 20c UPRabbits, Cavies, White Rats, Ducks, Pigeons, Hamsters

Write * J. E. STOCKER * Ramsey, N. J.

All Amino Acids (natural, synthetic, unnatural),Rare Sugars, Biochemical Products, Reagents, New Pharma.ceuticals in stock. Write or phone PLIza 7.8171 for completepre list

BIOS LABORATORIES, INC. 17 West 60th Street.aeYrk 23. N. Y.

SPRAGUE-DAWLEY, INC.Pioneers in development of the

standard laboratory rat

Box 2071 * Madison 5, Wisconsin * Phone 36134

L-PROLINE-Hydroxyprolins, L-Metblenine* AMINO ACIDS * BIOCHDlEMICALS* PRE-MIXED MICROBIOLOGICAL ASSAY MEDIA

H. M. CHEMICAL COMPANY, LTD.144 North Hayworth Avenue Las Angeles 48, Califonia

STAINSSTARKMAN Blogil L

* RARE* COMMON

Price list on Reqwst461 Bloor St., W.

* Toronto, Canada

S£~~~~~~~, 1~~~IwDiFLists more than 300 items for Research-

Biological, Microbiological, Bacteriological,Biochemical, Nutritional. Write

G I L CHAGRIN FALLS, OHIO

MODERN TECHNIQUE calls forEXO-KETON plastic COVERSLIPS

PATENTED / ) /

* UNBREAKABLE 22 mm round ...... $3.50 a thousand** WILL NOT CUT FINGERS 22 x 22 mm.3.00 a thousandWILL NOT ~~~~~~22x 40 mm .....5.05 a thousand* LAY FLAT 24 x 40 mm ........ 5.30 a thousand* 1/4 THE PRICE OF GLASS 24 x 50 mm ........ 6.05 a thousand

Other sizes priced in proportion.* These prices apply to orders of $25. Smaller quantities available from local dealers.

CHARLES F. HUBBS & CO. 389 Lafayette St., N. Y. 3 EST. 1855

U*

I25 E.

-- m-

PROIMSIONAL SERVICES SUPPUES AND EQUIPMENT

_-- -

SUPPLIES Al"IM EQUIPMEW

23May 18, 1951

NOW! Bring your AAAS Directory-up-to-date with the NEW

-CENTENARY SUPPLEMENTto the Summarized Proceedings, and aDirectory of Members who joined theAAAS during its Centennial Year 1948.

6 x 9 inches, clothbound, 392 pagesJanuary 1951 .... .... $5.50AAAS members' prepaid orders . $4.75

combination offer . . .

AAAS Proceedings and Direc-tory, 1940-1948, plu-s the newCentenary Supplement bothvolumes in one order-$1O.50AAAS members' prepaid orders

-$8.50

* order now, from AAAS-1515 Mass. Ave., N.W., Washington 5, D. C.Enclosed is. $.......... Please send me:

E CENTENARY SUPPLEMENT special COMBINATION OFFER

NAME .................................................

ADDRESS ..............................................

CITY & STATE .........................................S 5-18

Finre MARKEIT PLACEBOOKS * SERVICES * SUPPLIES * LQUIPMENT

If illiilIihllI !11ht!18 SUPPLIES AND EQUIPMENT1 I4'1'LABORATORY ANIMALS DOGS RATS RABBITSCATS PIGEONS HAMSTERS

Clean healthy well-fed animals MICE POULTRY GUINEA PIGSGuaranteed suitable for your needs.JOHN C LANDIS . Haerstown d.

Reasonably Driced-Dependable service

rtE eonMonocular& Binocular

illiont, adiustable, variable intensityumination all-pgroose lamps for loboratory,search and industry. RD.

INDLY& CO. MINEOLA, N. Y.

REICHERT FIELD MICROSCOPE with oil immersion, in caseguaranteed like new; Zeiss Tiyoda portable microscope, case54 x 7V/2 x 2X/2, $85.00. Write for detailed descriptions. IMO L.REECE, 12 Guy Park, Amsterdam, N. Y. X

"Your animal is half the experiment"

SWISS AIBINO MI(EALIINO- W RATS

P. 0. BOX 331albino farms * RED BANK, N. J.

YOU can TELL and SELLover 32,000 top scientistshere ... at a very low cost.

Your sales message in an ad this size costs only $35.00 at theone-time rate-less for multiple insertions. And the results!-well, here's what one of the many satisfied advertisers inSCIENCE has to say . . .

"SCIENCE is consistently our most iprofitablemedium. Business secured solely thru SCIENCE adshas been the backbone of our success in this field."

Prove to yourself the effectiveness of SCIENCE in increasingyour Market. Sales, and PROFITS-send your "Copy" NOW-or write for further information and Rate card N.. 27B.

rzweekly reaches 32,000 top scientistsSCIENCE 1515 Mas. Ave., N.W., Wash. 5, D. C.

SCIENCE, Vol. 113

LaMOTTECOMBINATION SWIMMING POOL SETfor small pools and those who do not care to installseparate units for chlorine and alkalinity.

This unit is appli-E- cable to the ranges of

chlorine and alkalinity

actually required forswimming pool water,and will enable the

alkalinity and chlorinevalues between thelimits required byState Health Depart-ment specifications.

They are coumplete with 3 color standards foreach test representing the upper and lower limitsof chlorine (0.2, 0.5, 0.7) and alkalinity (pH 7.2,7.6, & 8.0) together with reagents and necessaryglassware.

These units are contained in a plastic com-parator block, the top of which serves for makingtests. The plastic blocks are -Hroistuxe resistantand ideal for use around pools.

LaMotte Chemical Products CompanyDept. "H" Towson, Baltimore 4, Md.

INDEX of REFRACTION UQWDSValuable Aid for Identification of Minerals and other

* Solids by the Immersion Method of Microscopy* Range 1.400-1.700, intervals of 0.002, or as selected

Index Certified to + 0.0002* Range 1.71-1.83, intervals of 0.01

Write for Price List Nd-SR. P. CARGILLE 118 Liberty Street, New York 6, N. Y.

c

.0

24

tL

LAB-AID" EXPEDITERS- they speed-up laboratory chores

Cnic paraffin knife

1 10 Volts AC.- DC25 Watts

makes work with paraffin-embedded tissues quick andeasy. Great for cutting large blocks into small ones;for mounting blocks on a microtome object disc; forsquaring up blocks; for separating ribbons in a waterbath ... Hollow stainless steel handle doesn't heat up;spring switch under thumb gives Finger-Tip Heat Con-trol - easy to keep knife at the right temperature.When not in use lay knife in saddle rest -Blade UPkeeps knife hot; Blade DOWN current is "off."

1CIIXCOfl microslide dryerdelivers slides ready for staining in 7 minutesl Justdrop slides, in an Autotechnicon Slide Carrier, into thehatch, flip the switch and close the cover. A steadycurrent of warm, filtered air blowing over the slidescarries away all moisture, leaving them bone-dry anddust-free. The filter is replaceable. There's no distor-tion, either - the warm clean air is well below themelting point of paraffin.

31/2 wide_4" high121/4" long.1 10 Volts AC on75 Watts, ,

NidmK8xl te~ water bathinsures smooth, even spreading of your tissue ribbons.The water temperature is just right- never too hot ortoo cold, thermostatically held at any set temperaturefrom 200 to 60°C. There's no melting paraffin to dis-tort tissues- no folds or wrinkles, no bubbles due tofrequent water change. Temperature stays constant,day-in, day-out. And it's easy to see your sectionsagainst the dull finished black interior of the bath.

Size: 103/4" Diam; 33/4" HI-ghS'urdy; durable; water andxylolproof flnish.I I (n VntitoeAt_ nr THE TECHNICON COMPANY

215 East 149th Street, New York 51, N. Y.

Send me literature and prices on

DIII El Technicon Paraffin KnifeE Technicon Mkroslide DryerEl Technicon Constant Temperature Water Bath

Aaares s............................................e ................ ...............

City, Zone, State.

SPENCER No. 735 LAMP

Here is the illuminator for advanced microscopy youknew was bound to come . . . with convenient precise

controls for critical adjustment . . . with essential opticaland mechanical qualities to complement a fine microscope.

COOLER OPERATION. Sturdy die-cast housing dissipates heat.

* CRITICAL FOCUSING FROM EITHER SIDE. Rack & pinion movement.

NO TRANSFORMER. Lamp operates from 110 volt outlet.

PRECISION REFLECTOR ADJUSTMENT. 4So quick, simple, and accurate. *

|| RAPID BULB CHANGE. Lamphouse separates.Hinged lamp chimney opens to reveal bulb and reflector.

*PRECISE TILTING. Screw adjustment maintains any angle.

QUALITY OPTICAL SYSTEM. Two plano-convex lens elements.

IRIS DIAPHRAGM. Knurled ring control. +

FILTER HOLDER. Choice of single or multiple holder.

nination is essential for the. .IA :best results from any microscope objective,eyepiece and condenser. Your instrumentdeserves the Spencer No. 735. For furtherdetails write Dept. S3.

1iAmerican V uptucaiCOMPANY

Scientific Instrument DivisionBuffalo 15, New Yotk

el- !-='

S 'J f- ".

r,1.

-Pt,

1%

I.

I'7

%.cM-ild,C5t

IT.

i

V.

3,e

B.-

t'.

i.}i

I,_e

)-I;( -X.

istS

I-)

Correct illunL___ 1

2>!,1.

<j 4,St

r.,,

,/..

-) I*,SW'.'~

l-- -- ,- - -

., I -, t r-) ,,, , ", "- , '4'-

- d I -,.24 1-. "- "-. "k ,

I , *,, -:,. , .,-

t -. .;' '-, -

4. U C'.k , . T# .14-_ v

- V l -, ;--

4

:, { rtA

r- ' -- ; _ Cy, -