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S T A I N L E S S S T E E L T RIP L E B E A M T R IP-SCA L E......... .........

CAPACITY1,610grams

*STAINLESS STEEL*AGATE BEARINGS

No. 4050

BEAMS*SPEEDY

* COBALITE KNIFE EDGES* ACCURATE * DURABLE

* * VITAL FEATURES * *Stainless Steel

The beam and all exposed parts are of stainless steel,which is practically noncorrodible by laboratory fumes.In fact these stainless steel parts have been placed inthe following solutions for one month: AmmoniumHydroxide, Chroinic Acid, Formaldehyde, HydrogenSulphide, Sodium Hyposulphite, Nitric Acid, SodiumChloride, Molten Sulphur, and Sulphuric Acid, and atthe end of that period showed a total penetration ofless than .0003" for any solution. This resistance ofstainless steel insures for many years bright, clear,easily read scales, while the old designs with ferrousor nickel beams become unreadable in a comparativelyshort while. This exclusive advantage in the Welchbalance will be appreciated by all laboratory directors.Because of the use of Stainless Steel, it is possible tohave fine, sharp lines, which are easily read. Everytiny screw, rivet or nut, in this balance is of stainlesssteel.

Beam ArrestA beam arrest button is at the left end of the* basethus providing for rapid, accurate weighing. The

feature is particularly valuable, for the novice maylearn on this comparatively rough-weighing scale thatthe damping device should be handled gently so as notto throw the beam and increase rather than decreasethe oscillations.Covered Bearings

The stainless steel cover is provided so that no ma-terials can fall into the agate bearings which supportthe Cobalite knife-edges. This feature will be par-ticularly appreciated in the chemistry laboratory whereso often balances of this type are ruined, and particu-larly those with ferrous knife-edges or bearings, bysome of the salts falling on the knife-edges and intothe bearings.

Cobalite Knife-EdgesThe knife-edges are hard, corrosion-resistant Cobalite,a cobalt-chromium-tungsten alloy. Heretofore thesewere only found in "extra-cost," high-grade analyticalbalances. In industrial applications the remarkableperformance of this hard, corrosion-resistant materialis well known.

Complete with two extra weights, Each $18.9|W. M. WELCH SCIENTIFIC COMPANY

Established 18801515 Sedgwick St., Dept. E Chicago 10, Ill., U.S.A.Manufacturers of Scientific Instruments and Laboratory Apparatus

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overhead protectorWe believe that the best way to convince you of the superiorqualities of the Beseler VU-GRAPH Is to let you see them foryourself-rn action. That Is why we are offerin'g you a FreeDemonstration-at no cost or obligatIon-of this unique over-head projector that enables you to project material-and faceyour students at the some timelThe YU-GRAPH will project any transparency. It will projectopaque material In silhouette. It Is the ONLY projector that usesa patented film-extremely inexpensive-that enables you tomake your own stencil with pencil or typewriter. You can point,

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Vol. 107 No. 2768 Friday, January 16, 1948

Drilling- on, lF pAtoll, MarshallIslands:H. S. Ladd, J. I. Tracey, and G. G.Liii,. .. 51

Association AffairsReports of Chicago Meeting .............................. 55

News and Notes ........... : 58

Technical PapersEffect of Crude Polyporin on Seed Germi-

nation and Root Growth: A PreliminaryStudy:S. R. Bose, A. B. Bose, and K. L. Dey ............ 63

Preflooding Treatments With DDT for Mos-quito Control:C. C. Deonier, John A. Fluno, and E. Not-

tingham ....................................

The Presence of an Alcoholic, Ketonic Deriva-tive of Estrone in Human and Rabbit Blood:N. T. Werthessen, C. F. Baker, and B. Borci 64

Increase of Herbicidal Action of Concentrate40 and Oil Emulsion by 2,4-D:

Jose C.Mangual .................................

Importance of the Methoxy Group in Anti-fibrillatory Compounds:Joseph R. DiPalma and Joseph J. Lambert 66

Inactivation of Nutrients by Heating With Glu-cose:

A.B.Patton and E. G. Hill .................................... 68Effect of Suspended Silt and Other Substanceson Rate of Feeding of Oysters:Victor L. Loosanoff and Frances D. Tommers 69

In the LaboratoryOn the Use of the Campbell-Pressman Lyo-

philizing Apparatus for Urinary Extrac-tives:Herbert S. Strickler and C. Boyd Shaffer ......71

In Vivo Geiger-Muller Gamma-Ray Counterfor Radioisotope Distribution Studies:Nello Pace,, Robert Loevinger, and EnriqueStrajman ...... : 71

Book ReviewcCollege physics: mechanics, heat and sound:

Francis Weston Sears and Mark W. Zeman-sky.Reviewed by William A. Nierenberg ..................... 73

Organic analytical reagents: Frank J. Weleher.Reviewedby John H. Yoe ....................................... 74

A concise comparative anatomy:William Henry Atwood.

ReviewedbyThomasR.Forbes .............................. 74Die genauen Methoden der astronomisch-geo-graphisehen Ortsbestimmung:Th. Niethammer.

ReviewedbyCharlesH. Smiley .............................. 74Radar system engineering: Louis N. Ridenour.

Reviewed byW.D.Hershberger .............................. 74Foundations of algebraic geometry:Andre Weil.

Reviewed by W.V.D. Hodge .................................... 75Probit analysis: a statistical treatment of the

sigmoid response curve: D. J. Finney.ReviewedbyF. M. Wadley ..................................... 76

Scientific Book Register.......................... 76

(Cover photo by J. I. Tracey.)

Science, a weekly journal, is published each Friday by theAmerican Association for the Advancement of Science atJames F. McCarthy, Successor to The Science Press PrintingCompany, Lancaster, Pa. Founded in 1880 it has been since1900 the official publication of the AAAS. iEditorial and Ad-vertising Offices, 1515 Massachusetts Avenue, N.W., Wash-ington 5, D. C. Telephone, EXecutive 6060 or 61. Cableaddress, SCIMAG, Washington, D. C. Entered as second-class matter January 17, 1947, at the postoffice at Baltimore,Maryland, under the act of March 3, 1879. Application fortransfer to the postoffice at Lancaster, Pennsylvania, pending.

Articles offered for publication should be sent to the Edi-tor. The AAAS assumes no responsibility for the opinionsexpressed by contributors. Membership correspondence forthe AAAS should be sent to the Administrative Secretary.

Annual subscription, $7.50; single copies, $25; foreignpostage (outside the Pan-American Union), $1.00 extra;

2

Canadian postage, $.50 extra. Remittances and orders forsubscriptions and single copies, and notices of changes ofaddress should be sent to the Circulation Department, AAAS,North Queen Street and McGovern Avenue, Lancaster, Penn-sylvania, and 1515 Massachusetts Avenue, N.W., Washington5, D. C. Claims for missing numbers will not be allowed ifreceived more than 60 days from date of issue. No claimsallowed from subscribers in Central Europe, Asia, or thePacific Islands other than Hawaii or because of failure tonotify the Circulation Department of a change of address orbecause copy Is missing from the files.Change of address. Four weeks notice is required for

change of address. When ordering a change, please furnishan address stencil label from a recent issue. Addresschanges can be made only if the old as well as the newaddress is supplied.The American Association for the Advancement of Science

also publishes The Scientific Monthly. Subscription rateson request.

0Mildred Atwood Theo. J. Christensen

Acting Editor Business Manager

Publications Committee

Roger Adams, John E. Flynn, ~Irtley F. Mather,

Walter B. Miles, W. J. Bobbins, Malcolm H. Soule

[TENTSr ((). M

The Beckman Flame Photometer ex-tends the application of the ModelDU Quartz Spectrophometer, al-'ready widely used in all types oforganic analyses, to the qualitativeand quantitative determination ofchemical elements. It makes pos-sible amplified analytical approachto many problems such as metal-lurgical analyses, water analyses,biological determinations, soil analy-ses, etc., which have heretofore re-quired the use of tedious "wet"methods or of expensive instrumentssuch as the spectrograph.Samples in solution are atomized in a speciallydesigned- sprayer and introduced into hot oxy-gen-gas flame, which excites the spectral linesof the chemical elements. These lines are usedas the light source for a Model DU QuartsSpectrophometer, which serves to isolate thelines and measure their intensities. The instru-ment is useful for a large number of elements,including many heavy metals and alkaline earths.

The high resolving power and high photometricaccuracy of Beckman Spectrophometer are fullyutilized. This permits use of narrow monocho-inator slits resulting in minimum interferenceby background illumination from the flame.Measurements can be made on 5 cc and less than0.5 per minute consumed. The results are read-able directly from the dial.

Write for Technical Bulletin SP52.

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Shtaker--

6Blood Pipettes

Accept six blood cell diluting pipettes . . . twoin each cradle. Three separate cradles; eachcradle holds two pipettes.Each cradle has a separate vibrator control.

You can increase and decrease the vibration foreach set of pipettes.Each cradle has its own separate electric "on

and off" switch. That means the unit can bemade to operate so that two pipettes are shakingwhile the other two units are not in operation;or four pipettes can be shaking while the othercradle is not in operation.In most multiple pipette shakers, if you stop

the unit to take out one or two pipettes, all ofthe pipettes in the unit are standing still. Thusyou have to shake the pipette again because theblood has settled. In this Multiple PipetteShaker you can keep the units operating thatare not ready for counting. You only need turnoff the one you are going to count. This is a bigtechnical advantage. . . Individual vibratorycontrol and Individual "on and off" switch.The unit is constructed in a specially designed

steel housing mounted on rubber suction cups,for operation on 110-120 volts ALTERNAT-ING CURRENT. It stands 5 inches high, 8inches wide, 4j inches deep. It weighs 44 lbs.The finish is high gloss cream white baked enamelof finest quality.Each .. $45.00

STANDARD SCIENTIFICSUPPLY CORP.34-38 West 4th St.New York 12, N. Y.

NEW REVISED /GIIBOOKLET #677

containing broad list of productsexpertly made, by laboratory I NIJtitoi,controlled processes, ready for I ESTFVC1 /immediate use to save you vral-uable time and expense in yourlaboratory. GBI products as-

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GENERAL BIOCHEMICALS, INC.60 LABORATORY CHAGRIN FALLS

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Special ResearchProcedures

The following forms of Carotene iso-lated and purified by General Bio-chemicals, Inc., are currently available.

CAROTENE CRYSTALLINEALPHABETA90%0 BETA-10% ALPHA

CAROTENE in OIL250,000-50,000 and3,330 USP UNITS PER GM.

For Further Information and Price WRITE

GENERAL BIOCHEMICALS, INC.60 LABORATORY PARK * CHAGRIN FALLS, OHIC

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exclusive S drawer system*makes this the "alimpurpose" laboratory file

You can have them ALL in the same unit . . . 1"drawers, and 2" and 4", in any combination your filingneeds call for. Only "LAB-AID" files have this versa-tile tracking system which permits instant interchangeas filing demands vary. Drawers slide smoothly underfull weight of close-packed slides. Safety stops prevent

accidental withdrawal, and all-steel construction assurespermanent freedom from warping or binding.

Units are small enough (19" square) to fit easily ona desk, yet each will hold up to 6500 slides. Units canbe stacked to any height . . . staunch welded-steel con-struction includes interlocking angles for stability andweight-supporting strength. The "L.AB-AID" file is, in

simple truth, the "all-purpose"file for all laboratory needs - - .however large or small.

All drawers can be convertedfrom spaced - filing to com-.pact storage filing, or viceversa, thru these remov-able slotted separatory-liners.

currentfiling

Please send for Bulletin No. 1600

laboratory filing cabinetTH E TECH N I CO N COM PANY215 EAST 149 STREET, NEW YORK 51, N. t.

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Lasting Centration and Parfocality

Insured by B&L Threadless Cells

Elements of objectives in Bausch & LombLaboratory Microscopes are burnished intoself-centering, diamond-turned, threadlesscells. No cement is used. This method ofmounting eliminates the inaccuracy, anddifficulty of spacing or centering, char-acteristic of screw thread mounts. Thetolerance required between screw threadsis not close enough to maintain the high

accuracy demanded of B&L Microscopesat high magnifications.Thus, accurate centration and parfocality

are built-in the microscope, rather thanobtained by adjustments. More reasons

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