VPr

(have lots ofclean pipettes-

always on hand...I A

4

w;.As you can see above, it's no problem at oll to have plentyof clean pipettes always available- when you entrust 'thejob'to the Technicon Automatic Pipette Washer. Twice everyminute the washer swirls seven surging gallons of waterthrough the pipettes inside, flushing away clinging residues.In three minutes (six syphon-cycles) it delivers a full basket-load of immaculate pipettes (holds up to 200 pipettes I mland up to 18" long). The special alloy st jnless steel basketis proof against corrosive reagents, even',otassium dichro-mate and sulfuric acid. It carries pipettes, as a unit-loadthrough cleansing, washing, drying. Requiring no handlingof separate pipettes, it practically eliminates breakage andchipping. Bulletitn #6150 gives particulars- let us send itto you.

PyrexJar

Pipette PipetteRack Washer

automatic pipette washerTHE TECHNICON COMPANY. 215 East 149 Street. New York 51, N. V.

"BRONWILL"* WarburgMANOMETRIC RESEARCH APPARATUS

FOR PRECISE MICROGAS ANALYSIS

Smallest, Most Compactand Versatile Warburg Available!

* Exclusive, lagless, intramolecularheating.

* Temperature constancy +0.01°Cor better.

* Six reproducible shaking speeds,three amplitudes.

* Double capillary manometers.

* Magnetically operatedreaction vessels.

tiltingIE

DOUBLE CAPILLARY

MANOMETERS

Model UV, shown above, is a compact, circu-lar unit-only 20½2" diameter, 31 " high-rotatable through 3200 permitting any of the14 manometers to be quickly read. ModelUVL equipped for photochemical work alsoavailable.

A unique "Bronwill" manom-eter-a sturdy, single rodcontaining two capillaries . . .

one opened at top to atmos-pheric pressure; the other to a

three-way stop cock and thereaction flask. Adaptable toall Warburgs.

fZ4& *I"BRONWILL" is the trademark identifying products of Bronwill Scientific, Inc.

.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1BRONWILL SCIENTIFIC, INC. Dept. S-54j45 Russell Street, Rochester 7, New YorkPlease send full information on Bronwill Warburgs.

NameI

Position

Company

Address

City Zone State_

May 21, 1954

C

IA

Proven Performer In The Laboratory

CBYO-DESI|CCAT4IIFOR USE IN:* Histology* Cytology. Histopathology* Cytochemistry* Histochemistry

T he Tissue Cryo-Desiccator provides a sim-ple, rapid reliable and inexpensive methodof preparing frozen dried tissues.

Tissues are supported in a basket which hasmovable partitions to accommodate speci-mens of different sizes.

Temperature is measured under the same

conditions as the tissue. Liquid nitrogen isused to cool the tissue. Automatic sealing isachieved by atmospheric pressure.

This new Cryo-Desiccator is inexpensive to

operate and easy to use. Glass parts are heldto a minimum and the construction is rugged.

For further informnation write:

2385 RHODE ISLAND AVE., N.E.

Cut. No. 9-99 ........ Price $1450.00

FURNISHED WITH THEFOLLOWING ACCESSORIES:

* 1 extra glass tube for tissue heater

* 1 electric cord

* 1 flexible metal tube for attaching to pump

* 1 dial thermometer, Weston 0-180 Deg. F.

WASHINGTON, D. C.

SCIENCE, Vo1. 11I92A

CIRCULATION DEPARTMENTSC I ENCE1515 MASSACHUSETTS AVENUEWASHINGTON 5 DISTRICT OF COLUMBIA

GENTLEMEN:

YOUR ANNUAL BOOK ISSUE OF 23 APRIL 1954 (VOLUME 119 NUMBER '3C95)

COVERS COMPLETELY THE FIELD OF SCIENTIFIC WRITING, EDITING, AND

PUBLISH ING THAT I WOULD LIKE TO HAVE COPIES FOR W BOARD AND THE

EDITORS. DISTRIBUTION OF THESE COPIES WILL SAVE ME AN ENDLESS

AMOUNT OF ENDEAVOR WHICH COULD BE BEST CHANNELED ELSEWHERE.

MY PERSONAL CHEQQE FOR TWO DOLLARS AND FIFTY CENTS IS ENCLOSED

FOR W%HICH PLEASE FORWARD ME TEN COPIES OF THE ABOVE MENTIONED

ISSUE.

THANKING YOU FOR YOUR CO-OPERATIONS I AM

SINCERELY YOURS

WHITEFO C BELLp IlIPUBL IStR

SCICNCE, Vol. 119A4

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LEITZ MICRO-PROJECTORS

LoItzMicro-Pubojecor.i X b 11

LeltzMlcro-Proloctor XE-c_

For instruction uses in seminars, clinicsand classrooms. Either model will giveyou the utmost in image, brilliance andclarity. Both combinfe microscope andilluminating unit.

Leitz Micro-Projector X b II-with ob-jective and condenser nosepiece. Micro-scope can be used in 40ither horizontal orvertical position. Each objective has itsown special condenser to make changeof magnification quick and easy.

Leitz Micro-Projector XI-c-by far

the finest micro-projector on the market.Has synchronous objective-condenserchanger and horizontal built-in mechan-ical stage. Objectives are parfocalized.Controls for coarse and fine adjustmentare arranged on a common axis. Thesame area of the specimen remains inthe center of the projected image withall magnifications.

E. LEITZ, INC. Distributor of the world-famousproducts of Ernst Leitz, Weftlar, Germany

E. Loltz, Inc., Dept. S468 Fourth Avenue, New York 16, N. Y.

Please send me your brochure on the

Company

City State I

wwe .s _ - s sa s s sXos7ws: 5: ss= E-=es _ = _-J

May 21? 19 4 OA

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Active

STEROIDSIMMEDIATELYAVAILABLE

Statement of yourgovernment depart-ment dealing withatomic energy to-gether with "AtomicEnergy of CanadaLimited Form No.247" should befiled with eachorder.

For these formsand otherinformation,write to:

PHARMACEUTICAL arMANUFACTU

ESTITONE 6.&C14e Activity per mg.* 22.7 microcuries

Price per mg. $50.00

ESTRADIOLI 6-C'4e Activity per mg.e 2. 7 microcuries* Price per mg. $65.00

: PROGESTERONE 21-C14e Activity per mg.e 2.25 microcuries* Price per mg. $40.00.

DESOXYCORTICOSTERONEACETATE 21-C'4

Activity per mg.2.25 microcuries

* Price per mg. $40.00

nd CHEMICALJRERS

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Klett-Summerson Photoelectric Colorimeters-Colorimeters - Nephelometers- Fluorimeters-Bio-Colorimeters - Comparators - Glass Stand-ards-Klett Reagents.

Klett Manufacturing Co.179 East 87 Street, New York, New York

DENTAL CARIES and FLUORINE7'/2 x 10½2, clothbound, double column, Xi + 111 pages

FROM THE CONTENTS:H. Trendley Doss Epidemiological Studies in the United StatesRobert W"ver Epidemiological Studies in the British Isles and IndiaT. Ockerse Fluorine and Dental Caries in South AfricaPhilip Jay and Epidemiological Aspects of Oral Lactobacillus Counts in Fluoride

Francis A. Amold, Ir. and Non-Fluoride AreasWallace D. Armstrong Chemical Differences of Caries Susceptible and Immune Teeth

and a Consideration of Food Sources of FluorineHarold C. Hodge and Experimental Caries and a Discussion of the Mechanism of Caries

Reidar F. Sognnaes Inhibition by FluorineF. J. McClure Nondental Physiological Effects of Trace Quantities of FluorineB. G. Bibby Topical Applications of Fluorides as a Method of Combatting

Dental CariesFrancis A. Amold, Jr. The Possibility of Reducing Dental Caries by Increasing Fluoride

IngestionAbel Wolman Fluorine and the Public Water Supply

Published in 1946, this volume is attracting increasing atten-tion today. $3.50-Cash order price to AAAS members $3.00

TO: AAAS, 1515 Mass. Ave., N.W.

Washington 5, D. C.TWashinfon5,D.C. | Name .. . ........................ ....

Enclosed is $....... Please accept my order for Address .

.... ....... ...DENTAL CARIES AND FLUORINE City ...........-Zone.. ..State........

SCIENCE, Vol. 119

for Student Laboratory use

in Biology, Zoology and Physiology

A

Scientific Supply Division

The PHYSIO-STIMULATOR for students is a specially engineeredinstrument designed for laboratory and research work in Biology,

Zoology and Physiology. Direct reading dials indicate the

~ __.063t |frequency and voltage delivered and a control lever releases

the stimulating current either as a single impulse or as a series

P.O. Box 328 of impulses. This instrument is of professional quality through-

out, yet produced at a price which makes it practical for class-

room use, enabling each student to have his own stimulator to

carry on his experimentation.> uvuiluhie on request... FEATURES

Operates on 105-120 volt, 50.60 actly to the frequency"THE LATEST INFORMATION cycle AC dialed.

^K1 CD R 7e Dvl oltDirect reading controls: * provides in the "down'ON FREEZE DRYING regulate stimulating voltage position a single impulse

from 0 to I100. which may be repeated atOur research department has prepared a bulletin *rgulate frequoncy from 8 to will."Freeze-Drying of Tissues-Present Status of Tech- 75rulaes 8utoewill.

nology" which gives information on how to make 7puses per second. * neutral centero positionfreeze-drying a practical everyday procedure in Expanded ranges on voltage con- delivers no impulses.your laboratory. In addition to its vital role in the trol permit accurate determina- Switch circuit provided for oper-research laboratory this important new technique is tion of output in segment used ating a Marker.becoming a necessary part of college and university for ''threshold" measurements. Pilot lightcourses in histology. This illustrated bulletin con- Dial controls accurately and "On-Off" toggle switch

tains answers to many questions that have been easily roset to position. Ex tocbieasked of us concerning freeze-drying equipment and erimesca repetdCompact cabinet measurestechniques. The scientific literature in this field has periments cfn be repested or con- 6" x 6" x 6"lagged behind our progress in instrument develop- tinued at futuro times mprely by

ment. For this reason, quantitative data has been reseiting controls to previous pprovr d 6-ft. rubber covered

prepared showing the efficiency of our simplified de- positions. cord and rubber plug

sign. Included are complete Impulse Control Lever: Metal case, black crackle finish0-d 00 _jf 00v 0 --; details on this inexpensive, * provides in the ''up" posi-. Rubber feet on bottom and back

easy to use, equipment. tion a train of impulses ex- for normal or upright operation.PHYSIO STIMULATOR, Model N-103-B Complete (Less Leads). ..$37.50

Histological Freeze-Drying PHYSIO STIMULATOR, Model N-103-B5 provides 5-volt AC for

Marker Circuit; Complete (Loss Leads) .42.50

t: OUTPUT LEADS, Black and red colored vinyl insulated handles with

48" leads and molded tip plugs........................... 2.10

$575 f.o.b., Boston, Mass. LAB-TRONICS, INC., is an organization of internationally knownmedical and engineering research scientists dedicated to tho develop-

ment, design, and manufacture of precision apparatus for research insuch scientific fields* as Physiology, Nourology, Histohogy, Biochom-istry, Pathology, Neurosurgery, Physical-Chemistry, and Biophysics, and

enir m rin %nrni *a Arrnnn employing the most advanced techniques in electronics and engineoring.

I I 1S W. WASHINGTON BLVD. - CHICAGO 7, ILLINOIS

May 21, 1954

btuitN I tit UrttIAL I It. tuKr.Manufacturert of biological, medical, electronicand optical equipment, also research, develop-ment, custom designed scientific equipment.

Write: Snow and Union Sts., Boston 35, Mass.

7A

TRAVEL ARRANGEMENTSFOB THE AAAS BERKELEY MEETING

December 26-31, 1954In time or in cost, a trip from an eastern city to California is not much more than a round trip to

a midwestern city. Californians who for years have been attending meetings in the East have told theircolleagues that the continental distance is the same each way, and that it should be the turn of theEasterners to visit the Pacific Coast.

The Association is planning ways it may assist those who will attend the 121st AAAS Meeting onthe campus of the University of California at Berkeley, this December. The possibilities include:1. Low cost AAAS limousines from Oakland and San Francisco airports and railroad terminals di-

rect to the dormitory or hotel of each delegate.2. Arrangements for traveling together in AAAS cars on fast trains leaving Chicago, Washington,

D. C., and New York.3. Arrangements for chartering first class DC6, 6B, or 7 planes of scheduled airlines-at prices compar-

able with air coach travel. I

Note: In the following table of round-trip fares all figures include the new lowered 10% federal tax.

ROUND TRIPS TO OAKLAND OR SAN FRANCISCO FROM

Chicago Washington, D. C. New York

By Bus Time: 2 '2 days Time: 4 days Time: 4 days$82.50 $104.94 $112.31

By Rail Time: 2 /2 days - leaving Time: 3 '2 days -leaving Time: 3'%2 days - leavingevening, Dec. 24 and morn- evening, Dec. 23 and morn- evening, Dec. 23 and morn-ing, Dec. 31 ing Dec. 31 ing Dec. 31

Reclining $ 99.17 $147.62 $156.64seat coachFirst class $139.10 $204.33 $222.67Lower berth 46.20 60.06 63.58Total $185.30 $264.39 $286.25

By Air Time: 7-8 hrs., leaving a.m. Time: 10-11 hrs., leaving Time: 10-11 hrs., leavingor p.m., Dec. 26; returning a.m. or p.m., Dec. 26; re- a.m. or p.m., Dec. 26; re-a.m. or p.m. Dec. 31 turning a.m. or p.m., Dec. 31 turning a.in. or p.m., Dec. 31

Air coach $167.20 $215.69 $217.80(no meals)Chartered 1st class c. $178.00 c. $235.00 c. $235.00(meals included)First class $239.91 $312.18 $332.09(meals included)

PLEASE READ ABOVE TABLE, FILL OUT THIS COUPON, AND SEND IT TO

AAAS TRAVEL - Dr. R. L. Taylor1515 Massachusetts Avenue, N.W.Washington 5, D. C.

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

Address ............................................................................................I shall probably attend the AAAS Meeting in Berkeley. Without obligation I am interested in possible group

travel arrangements to San Francisco from:1. El Chicago O ] Washington, D. C. EONew York EJ Other city: .

2. My preferred manner of transport is:C) Rail- coach O Air- coach E BusEO Rail- 1st class El Air -chartered, 1st class n Other

EO Air- 1st class3. I would EO return east immediately after the meeting

E] like to make a side trip to .................................El remain indefinitely on the Pacific Coast

SCIENCE, Vol. 1198A

LII

No Wailing for

[BIAS OVENS

or $I[IIILIZ[R$

Model 831Freas Mlechanical Convection

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Write for Still the only laboratory oven line to offer aCATALOG 331 5-year Guarantee on Ileaters and Thermostat.

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