Aluminium's'I~~~~ ~ ~ ~ ~ ~ ~

*.. . .,*..*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*~~~~~~~~~sl

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The Improved Fisher-Gardner Mobilom-eter enables determinations of mobility byobserving the time required for a standarddisc to descend a fixed distance through asample.The Mobilometer has a monel metal

water jacket which permits temperaturecontrol and increases the range of the ap-

paratus to include semifluid greases as wellas other viscous products.The Fisher-Gardner Mobilometer with

Water Jacket is furnished complete withremovable sample cylinder for $83.00.When the mobility determinations (10 not require tem-perat ore control, the Mvobilonut r ithout water jacketcan be had for $65.00.

Headquarters for Laboratory Supplies

FISHER SCIENTIFIC CO. ElMER AND AMEND717 Forbes St., Pittsburgh (19), Pa. Greenwich and Morton Streets2109 Locust St., St. Louis (3), Mo. New York (14), New York

In Canada: Fisher Scientific Co., Ltd., 904 St. James Street, Montreal, Quebec

FOR BIOLOGICAL PROCEDURES

LONG-CONTINUED EXPERIMENTATION with animals in our own labora-tories has led to the development of many special diet materials whichwe have found valuable in nutritional research. While the prepara-tion of these materials in small quantities in the individual laboratorywould be troublesome and costly, our production facilities enable usto offer them-conveniently packaged and economically priced-asa service to investigators engaged in biological assay and research.

VITAMIN TEST CASEIN OBI. Uniformly free of vitamins A and D, as well as theknown factors of the vitamin B complex and vitamin K.

VITAMIN A TEST DIET, U. S. P. XII, GBI. For depletion of animals within allottedtime-weight limits specified for Vitamin A assays.

RACHITOGENIC DIET NO. 2, U. S. P. XII, GOI. For depletion of animals withinallotted time-weight limits specified for vitamin D assays.

VITAMIN B COMPLEX TEST DIET GBI. For use with suitable animals and ex-periments, to produce deficiencies of thiamine chloride, riboflavin, niacin, pyri-doxine and pantothenic acid.

SALT MIXTURE NO. 2, U. S. P. XII, GBI. For preparing vitamin A test diet andalso as a mineral source in the preparation of most laboratory diets.

'WRITE for complete list and prices of these and other diet materi-als, including crystalline vitamins, amino acids, casein hydroly-8ate, biotin and other chemicals of biological significance.

GENERAL BIOCHEMICALS, INC.60 LABORATORY PARK CHAGRIN FALLS, OHIO

16011td

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Vol. 108 No. 2794 Friday, July 16, 1948

CONTENTS

Scientist and Politician as Partners:The British Parliamentary and Sci-entific Committee: Hugh Linstead ........ 47

ObituaryRollin Thomas Chamberlin: J Harlen Bretz .... 50

Association AffairsCentennialCelebration Notes ................................ .... 52

News and Notes .54

Comments and Communications 57

Technical PapersAn Unidentified, Filtrable Agent Isolated From

the Feces of Children With Paralysis:Gilbert Dalldorf and Grace M. Sickles ............ 61

Human Saliva as a Germination Inhibitor:Dvora Yardeni ............ ......................... 62

The Visibility of Moving Objects: Elek Ludvigh 63

In the LaboratoryMethods of Automatic Watering of Plants:

John G.Seeley ..............................................................................Use of Thin Kidney Slices and Isolated Renal

Tubules for Direct Study of CellularTransport Kinetics: Roy P. Forster .....................

Magnetic-Flea Agitating Device forMicrotitration:

C.LloydClaff .. ................................................

Book ReviewsEncyclopedia of vocational guidance.

(Vols. 1 & 2): Oscar J. Kaplan. (Ed.)ReviewedbyEdward J. Stieglitz ..............................

Modern colloids: an introduction to the physicalchemistry of large molecules and small par-ticles: Robert B. Dean.

ReviewedbyErnstA. Hauser ....................................

Scientific Book Register. .....

(Cover photo by courtesy of the U. S. Navy.)

Science, a weekly journal, is published each Friday by theAmerican Association for the Advancement of Science atThe Business Press, Incorporated, N. Queen St. and McGovernAve., Lancaster, Pa. Founded in 1880. it has been since1900 the official publication of the AAAS. Editorial and Ad-vertising Offices, 1515 Massachusetts Avenue, N.W.. Wash-ington 6, D. C. Telephone, EXecutive 60 or 61. Cableaddress, SCIMAG, Washington, D. C. Entered as second-class matter at the Post Office at Lancaster, Pa., January 13,1948, under the Act of March 3. 1879. Acceptance for mail-ing at the special rate postage provided for in the Act ofFebruary 28, 1925, embodied in paragraph 4, Sec. 538. P. L.and R., authorized January 13, 1948.

Articles offered for publication should be sent to the Edi-tor. The AAAS assumes no responsibility for the opinionsexpressed by contributors. Membership correspondonce forthe AAAS should be sent to the Administrative Secretary.Annual subscription, $7.50; single copies, $.25: foreign

postage (outside the Pan-American Union), $1.00 extra;

2

Canadian postage, $.50 extra. Remittances and orders forsubscription and single copies should be sent to the Circula-tion Department, AAAS, North Queen Street and McGovernAvenue, Lancaster, Pennsylvania, and 1515 MassachusettsAvenue, N.W., Washington 5, D. C. Claims for missing num-bers will not be allowed if received more than 60 days fromdate of issue. No claims allowed from subscribers in CentralEurope, Asia, or the Pacific Islands other than Hawaii or be-cause of failure to notify the Circulation Department of achange of address or because copy is missing from the files.Change of address. Four weeks notice Is required for

change of address. This should be sent to Sokenoe, 1515Massachusetts Avenue, N.W., Washington 5, D. C. Whenordering a change, please furnish an address stencil labelfrom a recent issue. Address changes can be made only if

the old as well as the new address is supplied.The American Association for the Advancement of Science

also publishes The Scnentifle Monthly. Subscription rateson request.

Mildred Atwood F. A. Moulton

Acting Editor Advertising Manager

Publications CommitteeFarrington Daniels, John E. Flynn, Kirtley F.

Mather, Walter B. Miles, Malcolm H. Soule,Steven M. Spencer

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TRANSMISSION MEASUREMENTS

_ j ; ~~~~~~~~MODEL DUSPECTRO-PHOTOMETER

Ls A DIDYMIUMF1AIYUFL TER+0 I I/1 wI\D1\11 11 E _ Bi LHL~71EASURED ON A BECKMANNo.2 0 Ef3 E A: :jTVffllfflfm U r EMKffiSPECTROPHOTOOMETERSO0 *00 500 000 700 800 900 1000 1100 1200

WAVC LCNGTH MILLIMICRONS (PAn)

No. 29600 Beckman Model DU Spectrophotometer, Quartz Monochromator,permits rapid measurement of percent transmission and optical density of sub-stances in the wavelength range 320 to 1000 millimicrons. Use of No. 29650Ultraviolet Accessory Set will extend the range to 220 millimicrons. Thewavelength scale is one meter long, calibrated in millimicrons of wavelengthand transmission values are shown directly in both percent transmission andoptical density. For complete description write for Bulletin 1 04A.

* Band widths of 5 millimicrons and narrower may be used.* Easy-to-read wavelength scale may be read to 0.1 millimicrons

in UV and 1 millimicron in Infrared. 0* Reproducible wavelength settings.* Stable and sensitive phototube and amplifier circuits.* Basic instrument for fluorescence, reflectance and flame

photometer measurements.* Now immediately available from Cenco.

CENTRAL SCIENTIFIC COMPANY..%entij;c (f3 4patatu|

1700 IRVING PARK ROAD, CHICAGO 13

NEW YORK BOSTON SAN FRANCISCO NEWARK LOS ANGELES TORONTO MONTREAL

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44,4g-4e049 fJ Ah

Science Writing Awards

In this postwar world, science has amajor role. Some look to science toalleviate or eliminate disease . . . someexpect it to ensure and guarantee a per-manent peace . . . still others expect thedevelopments of science to unfold a newera of sustained economic prosperity.The broad attainment of these goals de-mands a well informed public. Sciencemust be intelligently, accurately andmeaningfully explained to the layman so

that he may understand its possible con-

tributions and also its limitations in ref-erence to problems of human welfare.

The Westinghouse Educational Founda-tion and the American Association forthe Advancement of Science feel thatspecial encouragement should be given tothe writers who accept the responsibilityof interpreting scientific research andprogress to the public. Believing firmlyin the worth-whileness of this objective,the Foundation and the Association havejoined together for the sponsoring andadministering of the AAAS-George

Westinghouse Science Writing Awards.The fourth series of Awards and the 1948competition period are now being an-

nounced.

Two $1,000 prizes will be given-one fornewspaper and one for magazine sciencewriting. Citations for distinguishedjournalism will be awarded to the publi-cations sponsoring the winning articles.The competition period is from October16, 1947 to July 31, 1948 for newspaperstories and from October 1947 throughJuly 1948 for magazine articles. Allentries must reach the Managing Com-mittee on or before August 7, 1948. Thearticles must have been published ineither a newspaper or magazine of gen-

eral circulation within the continentallimits of the United States. The award-ing of the prizes will take place duringthe Centennial Celebration of the As-sociation in Washington, September13-17, 1948.

For complete information, rules and entry blanks write to

The Chairman of the Managing CommitteeAAAS-George Westinghouse Science Writing Awards

1515 Massachusetts Avenue, N. W.Washington 5, D. C.

III

iIIl-E4

m j M j [P 21 [P 2EMp IP 5 91 0,1P . 0 . IM, 0,1P, . -1

WAWM, 1

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Twice every minute the TECHNICON PipetteWasher completes its syphon-cycle . . . seven surg-ing gallons of water to loosen and dislodgeclinging residues. Wastes are then literally sweptout of the pipettes by the violent suction set up dur-ing the brisk ten-second emptying phase.

Only the Technicon washer offers such rapidity andthoroughness, delivering in six cycles a full basket-load of immaculate pipettes (capacity 200 of 1 mlin 1 00th's, up to 1 8" long). The stainless steel

basket, proof against corrosive reagents, carriesits load of pipettes undisturbed through everystage: cleansing, washing and drying. Requires noindividual handling, no shifting from container tocontainer, practically eliminates breakage andchippage. A must for the busy laboratory: let ussend you Bulletin #6150 giving particulars.

THE TECHNICON COMPANY215 E. 149 St., New York 51, N. Y.

No fuss or muss . . .

pipette washing canbe as easy as this

LexIcon~7~,V*lZZ.f PIPETTE WASHER

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HERBACH & RADEMAN OFFERS ANOUTSTANDING NEW TYPE OF

GEIGER-MUELLER COUNTERDesigned for:

Nuclear, Medical, Biophysics& Industrial Tracer Research

Type - GM100GLASS BUBBLE WINDOW G-M

COUNTERFor Alpha, Beta, and Gamma-Ray Detection

SPECIFICATIONSWindow Thickness-2.5 mg/cm2, will transmit

30 KEV Beta ParticlesOverall Dimensions-4" length, 3/4" diameterCathode Dimensions-copper tube, 2" length,

1/2" diameter, oxydized to retard photo-sensitivity

Anode-3 mil tungsten wireSelf-Quenching Mixture-Spectroscopic Argon-

Anhydrous EtherLife of Mixture-5 x 1 08 to 109 countsThreshold Voltage-825-850 voltsOperating Voltage Range-875 to 1 1 00 voltsPlateau Slope-4% per 1 00 voltsPlateau Length-At least 200 voltsDead Time-80 microseconds at operating volt-

age of 1 000 voltsCOUNTER walls can be coated with opaque

dielectric to keep out light.As supplied with a non-oxydized cathode(TYPE -GM1OOB), the tube can be used as aphoton counter in the 2000-3000 A ultravioletregion for spectroscopic, flame detection, andbiophysics applications.PRICE .. $34.50

TYPE - GM100Thoroughly proven in use by research workers inNuclear Physics and Artificial Radioactivity, thiscounter combines great sensitivity with ruggedconstruction and convenient size. Stable pulsecharacteristics and very short intrinsic time lagsmake this GM tube outstanding for high speedcounting and for coincidence techniques. Re-solving times as short as 0.15 microseconds forsuitable coincidence circuits can be used with-out genuine coincidence losses.The result of over 1 3 years of experience in themanufacture and development of G-M countersis your assurance of complete reliability. Everytube is carefully produced to rigid specificationsand fully inspected and tested.

U_.

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A ARGONHELIUMKRYPTONNEONXENON

and Standard or Speciai

MIXTURESLINDE rare gases are spectroscopically pure-argon,helium, neon, and standard mixtures are availablein one- and two-liter glass bulbs and in cylinders;xenon and krypton are available in liter andfractional-liter bulbs.

The word "Linde" is a trade-mark of

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GARCEAU ELECTROENCEPHALOGRAPHSA.C. Operated No Batteries

Inkless Writing Require no ShieldingShipped Ready to Run Prompt Delivery

THE JUNIOR GARCEAUELECTROENCEPHALOGRA H

A simplified inexpensive instrument for recording electricalpotentials of the brain. Built-in interference eliminators per-mit use anywhere. Inkless records-no photography or film-development required. Instantaneous localization with any2 of the 10 leads

All Garceau Electroencephalographs operate en-tirely from the 115 volts 50 or 60 cycle power lines.

ELECTRO-MEDICAL LABORATORY, INC.HOLLISTON, MASSACHUSETTS, U.S.A.

6

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STANDARD FOR RESEARCHAND DEVELOPMENT

The Carver Laboratory Press is in constant use byengineers, chemists and laboratory technicians for

development, research and instruction work; com-

pression and crushing tests, testing of single Cavitymolds, preparation of samples, etc. The Press is a

complete, self-contained hydraulic unit. Accuratelycontrolled pressures to 20,000 Ibs.; 6-inch gauge

rigidly mounted on base. Carver Standard Accessoriesinclude Electric or Steam Hot Plates, Carver Test

Cylinders, Swivel Bearing Plates, Cage Equipment,available from stock. Special gauges can be suppliedfor low pressure work.

. . aiding the Stateof Florida

in soil testing.

"Six Carver Presses are used daily forthe numerous soil tests required in ourmodern road building program," saysH. C. Weathers, division engineer, StateRoad Dept. of Florida.

"One of these presses is used in the Division ofTests' Soil Laboratories, and others in the 5 Divi-sion Soil Laboratories in the State. The Presses areused in testing soil samples to determine relativebearing values. They have given excellent service,and are superior to any other method previouslyused for this work, being faster and the applica-tion of the specific load is assured."

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I FRED S. CARVER INC.HYDRAULIC EQUIPMENT

I 341 Hudson St, New York 14, N. Y.

Please send catalog, describing CarverLaboratory Pressand Standard Accessories.

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

FIRM...........................................................

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

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SAVE just one heat, or batch, by accuratespectrum measurement with this new Bausch& Lomb Densitometer, and you may save itsfull price. A substantial saving in man-hoursaccumulates day after day, too, to make it aneconomical investment for your spectro-graphic laboratory.

This new compact, self-contained instru-ment includes a highly efficient projectionsystem; horizontal stage with selective man-ual or motor-driven scanning; and built-inamplifier and micro-ammeter. No highly sen-sitive galvanometer is used. Vibration trou-

bles are minimized, and the long light pathfrom densitometer to galvanometer is elimi-nated. Entire unit occupies only a space 36inches square. New speed, simplicity, andaccuracy of operation are important perform-ance advantages. Limited quantity availablemakes it necessary to allocate units accordingto date of order.

THE NEW BAUSCH & LOMB DENSITOMETER8