SCIENCENEW SERIES FRIDAY MAY 18, 1945 SUBSCRIPTION, $6.00VOL. 101, No. 2629 7 SINGLE COPIES, .15

Bausch & Lomb Type "R"Photomicrographic Equip-ment provides a convenientand efficient means of using astandard microscope for pho-tomicrographic work. Cam-era may be used in vertical orhorizontal position and ismounted on the same supportas the illuminating unit. Pref-erence rating desirable forprompt delivery. Bausch &Lomb Optical Company,Rochester 2, N. Y.

Published weekly by the American Association for the Advancement of Science at Lancaster, PaEntered as second-class matter July 18, 1923 at the Post Office at Lancaster, Pa., under the Act of March 3, 1879.

2 SCIENCE-ADVERTISEMENTS VOL. 101, No. 2629~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

/Ah /DD4"R \ \ Each gla8s i8 heat-sealedin a moisture-proof cello-phane envelope

FS Haemacytometer Cover GlassesThe result of modern technique applied to the

grinding and polishing of optical surfacesRectangular shape, 20x26mm, 0.4-0O.6mm thick....Within National Bureau of Standard's specification(± .Ol.m)..... ach cover heat-sealed in cellophane,12 to a box.

FS Micro CultureHanging Drop Slides

Used for living specimens25 x 75mm x 5mm thick; well has 16 4mm opening, 3 mm deep. Top our-face matte; bottom surface opticallyground and polished flat to eliminateswaying of slide on stage of micro- $/scope.FISH-SCHURMAN CORPORATION

230 East 45th Street, New York 17, N. Y.

Fish-Schiuuina

Our large weekly production of 15,000 mice, 500rats and 1200 guinea pigs enables us to supplyregular orders promptly. In addition conserva-tive estimates of production usually make it pos-sible for us to fill emergency orders on time.

_,_

ERIC SOBOTKAFOR IMMEDIATE DELIVERY

RESEARCH MICROSCOPESMICROSCOPE LAMPS

17 EAST 40TH STREET

NEW YORK, N. Y.

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MASTER A NEW LANGUAGEquickly, easily, correcty by

LINM U A P HONEThe world - famous Unguaphone ConversationalMethod brings voices of native teachers INTO YOUROWN HOME. You learn the new language byLISTENING. It's amazingly simple; thousands havesucceeded.HOME-STUDY COURSES IN 29 LANGUAGES

'Send for FREE book-LINGUAPHONE INSTITUTE31 RCA Building, New York 20, N.Y. * Circle 7-0830

LINGUAPHONE INSTITUTE,37 RCA Bldg., New York 20, N.Y.Send me the FREE Linguaphone Book.Name ..........................................Address ... City.Language Interested..............................

1,

SCIENCE-ADVERTISEMENTS VOL. 101, No. 26292

SCIENCE-ADVERTISE.MENTS 3

Steam Heat only.

L~2td/e REFLUX STILLfor pure distillation

THE Castle Reflux Still produces approximately10 gallons of pyrogea-free distillate per hour, witha greater degree of purity than any other standardapparatus or plocess. It is completely automaticand is constructed with evaporator for quick, easycleaning when necessary.The Castle Reflux Principle permits partial purifi-cation of the water even before it gets to the evap-orating chamber. Overflow deconcentrating tubeprevents concentration of solids in evaporatorwhich has 27-inch height and baffle design to pre-vent contamination of condenser by foaming orsplashing. It operates on the Reflux Principle inwhich the primary condenser returns one quarterof the vapor . . particularly the larger particles

.to the evaporator and only the finest vaporpasses over to the secondary condenser producingthe final condensate.For further details of the Castle Reflux Still,write: Wilmot Castle Co., 1212 University Ave.,Rochester 7, N. Y.

cftdID LIGHTS ANDSTERILIZERS

THE CARVER

LABORATORY

PRESS

Scal9d.."d n Hide4C'J4c0eu0m

The Carver Laboratory Press is precision-made forlong and faithful service. Powerful but compact, thisversatile press is augmented by standard accessorieswhich permit all kinds of tests, from molding plasticsto crushing tests requiring up to 20,000 lbs. pressure.Each accessory gives you the practical advantage of ahydraulic press made to order for a definite need.The Carver Press is in use in physical, chemical, gov-ernmental and industrial laboratories. Prompt Deliv-eries. Write for latest catalog.

FRED S. CARVERHYDRAULIC EQUIPMENT341 HUDSON ST. NEW YORK 14

j

MTAY 18, 1945

4 SCIENCE-ADVERTISEMENTS VoL. 101, No. 2629

STIRRERSWith COMPLETE Speed Control

*. _

7605

Price as

illustrated =_to~A

t 1 dI<

Laboratory Apparatus.and Supplies of all Kinds

Inquiries Invited

* Rheostat control from 0 up.* Regular standard motor suitable for continuous

service 1 lov.* Plenty of power -will stir. anything up to

molasses.

* Fume resistant motor.

* Steel support rod.* Can be cfamped to any standard laboratory

support. a

* Rugged chuck-Cadmium plated for 1/4" rod.

* Operates on either A.C. or D.C. 11oV.

4 SCIENCE-ADVERTISEMENTS Voi., 101, No. 2629

A

In

SCIENCE-ADVERTISEMENTS

Bacto-AgarBacto-Agar is a purified

Agar prepared from domes-tic material. In the manu-facture of Bacto-Agar ex-traneous matter, pigmentedportions, and salts are re-duced to a minimum, so thatthe finished product in theform of fine granules willdissolve rapidly, giving clearsolutions.

DIFCO LABORATORIESINCO K PO B A TE D

DETROIT 1, MICHIGAN

Research Spectrometer

,p

Readings can be made to 20 seconds. The objectives have a 30mm aperture and 250mm f.l. The telescope is pro-vided with rack and pinion focusing and 10X Gauss Eyepiece. A bilateral slit with stainless steel jaws 1Omm long,an adjustable comparison prism and decker are mounted on the collimator.This spectrometer is recommended for research work in educational and industrial laboratories. It is a high gradeinstrument that assures satisfactory results through convenient manipulation and accurate measurements insuredby the rigidity of its parts, the stability and convenience of adjustments, and quality of the optical parts. Thelarge circle is provided with two verniers and is mounted on accurate and substantial centers.

Delivery from stock with suitable priority

THIE GAERTNER SCIENTIFIC CORPORATIO1204 Wri#htwood Avenue Chicago 14, U. S. A

PhotoelectricpH1 Determination

with

LUMETRON Colorimeter Mod. 400* Highly acurewo pH measuremts* Covering the complete pHamnAm* Applicable to a rat ait of pe problems

While serving as pH meter, LUMETRON MOD.400 is equally suited for all colorimetric and turbid-imetric tests in chemical analysis. Price $130.00

95 MadismRAVe. PHOTOVOLT CORP. NewTork 16, N.Y.Write for literature on Photoelectrc pH Determirzown.1 Li

Le

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MAYr 18, 1945 5

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6 CEC-DETSMNSVL 0,N.22

.00

565717 Needle, only, En.graving. For use withengravingL pencil No.S-65715. Per packaeelof20 needles............. S0.1is

S-65718 Needle, only. En-graving, Tantalum Car-bide Point. For use withengraving pencil No.S-65715. Hard needle rec-ommended for engravingextremely hard materialsand for ordinary engrav-ing with minimum sharp-ening. Each ...........$2.00

5-65719 Knife, only, WideBlade. For use with en-graving pencil NoS-65715. Cuts cardboard,thin wood, cloth, paper,etc. Depth of cut, 3/16inch. Foot gauge S-65721must be used with theseknives for regulatingdepth of cut. Per packageof 5 blades $........S0.50

S-65720 Knife, only, Nar-row Blade. For use withengraving pencil No.S-65715. Cuts cardboard,thin wood, cloth, paper,etc. The narrow blade per-mits cutting of intricatepatterns in small areas.Depth of cut, 3/32 inch.Foot gauge S-65721 mustbe used with these knivesfor regulating depth ofcut. Per package of 5blades.$.... SO.50

AZ

The Vibro-Tool provides a

simple method of permanentlymarking glass or metal objects.

Perfectly balanced to fit thehand and light weight (1 lb.)

the Vibro-Tool handles as easily

as writing with a pencil. Marking is accomplished mechanicallyby vibrations of the marking tool-120 reciprocal strokes per

second-consumes less current than a 60 watt light bulb.

The use of the Vibro-Tool ranges from engraving simple iden-tification numbers and chemical nomenclature on bottles or slidesto engraving special calibration markings on equipment and ex-

perimental dials, gauges and measures.

A few suggested uses include marking test tubes, beakers, jars,flasks, watch glasses, stock bottles, microscope slides, reagent

bottles, manometric scales, metallurgical specimens, etc.

S-65715 PENCIL VIBRO-TOOL Glass, Metal and Plastic Engraving,Electric. Complete with 20 No. S-65717 needles suitable for engraving on

glass, metal and plastic.For operation from 115 volt A. C. 60 cycle circuits................................$ 7.50

S-65721 FOOT GAUGE needed for regulating depth of knife cut........$ 0.95

E. H. SARGENT & CO., 155-165 E. Superior St., Chicago 11, Ill.

Michigan Division: 1959 East Jefferson, Detroit 7, Michigan

VOL. 101, No. 26296 SCIENCE-ADVERTISEMENTS

C~"

SCIENCE-ADVERTISEMENTS 7

a X microslide filing cabCinet offering_~ 5% greater

* " - ^wcapacityat amazingly low costs*This new "LAB-AID" cabinet is the ultimate solu-tion to the filing problems encountered in thelaboratory. It is of welded-steel, fire-resistant con-struction throughout. Files 3"x 1" or 3"x2" micro-slides, 2"x2" transparencies, large lantern slides,index cards, even paraffin blocks ... in single-rowdrawers, all fitting interchangeably into a smooth-tracking master drawer-rail system. Unit-sections,assembled` in any combination, can be used singly,or stacked to any convenient height. With all theseadvantages, the cost-per-slide capacity in the"LAB-AID" cabinet is the lowest ever. Investigatethis remarkable equipment ... the coupon willbring details.

the noew steel -

Ilborn ory filing cabinetA single "LAB-AID" unit-section. Anycombination of drawers can be supplied.

1 East! 1 49:Str A. .i ,,. 'At '' "New York 51, N. Y.,

Please send me details concerning your "L-AID" micro-slide filing cabinet.

~~~~~~Name -By merely dropping in a pat-ented "LAB-AID" sloitted liner,_________________________________________________any drawer is converted fromstorage filing to individual- Streetslide filing, or vice-versa.

THE Tcnoncon COMPANY

MAY 18y 1945

SCIENCE-ADVERTISEMENTS VoL. 101, No. 2629

U N U SUAL WAlR B1A R GAIN S

IN LENSES & PRISMS

ALL ITEMS FINELY GROUND and polished but edges slightlychipped or other slight imperfections which we guarantee will notinterfere with their use. Come neatly packed and marked.YOU CAN EASILY MAKE Telescopes, Magnifiers, PhotographicGadgets and Hundreds of Experiments with these Low Cost Lenses.TO TRANSLATE millimeter measurements; 25.4 mm. equals oneinch.

MISCELLANEOUS ITEMS

TANK PRISMS90-45-45 degree prisms of huge size-5-3/4" long, 2-1/8"wide, finely ground and polished. Used to build a Peri-scope . . . excellent also for experiments, classroom demon-strations at high schools, colleges, camera clubs, astronomyclubs. Some of our ingenious customers have used thesePrisms to make camerastereo attachments, photometer cube,range finder, etc. Normally, these Prisms would retail fromabout $24 to $30 each.

SILVERED TANK PRISMStock #3004-W .. ......... $2.00 each Postpaid

(Illustrated Booklet on Prisms Included FREE)

FOUR SILVERED TANK PRISMSSPECIAL $7.00 Postpaid

This is the most sentational bargain- we have ever been ableto offer.

WAR SURPLUS ACHROMATIC LENSESStock Dia. F.L.No. in mms. .in. mms. Comments Price

6019-W 15 41 Cemented 6006111-W 16 36 Cemented 75¢6094-W 16 75 Cemented $1.006066-W 32 132 Uncemented 7506115-W 46 108 Cemented $1.00USES:-Use these Lenses for making Projecting Lenses,Low Power Microscope Objectives, corrected Magnifiers, sub-stitute enlarging Lenses, Eye-Piece Lenses, Macrophotog-raphy, gadgets, optical Instruments, etc., etc.

RAW OPTICAL GLASSAn exceptional opportunity to secure a large variety ofoptical pieces both Crown and Flint glass (seconds) in vary-ing stages oi processing. Many prism blanks.Stock #703-W ...... 8 lbs. (minimum weight) $5.00 PostpaidStock #702-W 1'/2 lbs .................. $1.00 Postpaid

PORRO PRISM SET FROM ARMY'S 6 POWERBINOCULAR

Consists of 2 Porro Prisms to make an erecting system fora Telescope.Stock #3010-W .$2.00 Postpaid

35 MM FILM ENLARGING LENS SETConsists of 2 Achromatic Lenses to use at a speed of aboutF.8. These make a good substitute until Anastigmat En-larging Lenses again become available.Stock #6096-W .$1.50 Postpaid

8 MM MOVIE PROJECTING LENS SETConsists of 2 Achromatic Lenses, diam. 18 mms. and a F.

L. when combined of approximately one inch.Stock #4011-W ............ $1.20 Postpaid

COLOR FILTERS1 Red and 1 Yellow in Following Diam.

20 mm. (seconds) 40¢ 45.5 mm. (seconds) ..... 90¢

32.5 (seconds) 70¢ 31 (seconds) 70037 (seconds) 70¢ 29 mm. (perfect) $1.00

Minimum order on Above ........................ $1.00ORDER BY SET OR STOCK NO

Stock Item Price

No.

3006-W Porro Abbe Prism .25 each3016-W Pentagon Prism .75 each2024-W 10 Pieces Circular Plate Glass

(Diam. 31 mm.-tor making filter) .25 each1004-W 2 Reducing Lenses 1.203001-W Lens Surface Prism 2.00 each503-W No. 1 Sable Hair Lettering Brush 1.00 dozen3021-W Amidi Roof Prism (3rd grade) .25 each

4009-W Heat Absorbing Glass 4" x 5" .35 each4010-W Heat Absorbing Glass 2" x 2" .10 each2016-W 17 mm. Diam. Gunsight Reticle 10 each2020-W 40 mm. Neg. Lens, Cross Lines .25 each3020-W Right Angle Prism 48 mm. wide .35 each

(3rd grade)523- 6 Threaded Metal Reticle Cells .25

COMPLETE SET OF LENSES AND THE PRISMSTO MAKE A MONOCULAR (TELESCOPE)

These are from the Navy's 7 Power Binocular with 2"

diameter objective lens.Stock #5100-W Monocular Set ..... ........... $5.00 Postpaid

KELLNER EYE PIECE LENSFocal Length 1-1/4- inches. Diam. of eye lens 16 mm. Diam.of field lens 25 mm. Comes unmounted but eye achromat al-ready cemented.Stock #6108-W .............................$. 1.00 Postpaid

POLAROIDDiam. 3-5/8 Inches. One round piece of polaroid (mountedbetween glass). Supplied in individual cloth containers.Limit-2 pieces to a customer.Stock #623-W .......................... $1.50 each Postpaid

PERFECT ACHROMATIC TELESCOPEOBJECTIVE LENS

Diam. 1-3/4 inches, F.L. 20 inches.Stock #6091-W ............. ................ $5.00 Postpaid

CLEANING BRUSH SETFor Lenses, Optical instruments, etc. Perfect quality, 12"flexible plastic handle, hollow circular construction. Rangefrom stiff to very soft. 4 brushes to set.Stock #504-W (Reg. $6.00 value) ....... ............... $1.00

MAGNIFIER SET5 Magnifying Lenses ..... ........... Powers from 1 to 10.Stock #1026-W .............................. $2.00 Postpaid

RETICLE SET5 assorted, engraved reticles from U.S. Gunsights.Stock #2035 ................................ $1.00 Postpaid

SCOOP! CONDENSING LENSES FOR 36 MMPROJECTORS OR ENLARGERS

Crown Optical glass, plano-convex, diam. 52 mm. F.L. 93mm.Stock #4022-W .....a $1.25 each Postpaid

(Order 2 for a set)

TANK PERISCOPEComplete Set Mounted Components

Rugged, strong, originally constructed for U. S. Tank Corps.Consists of 2 fine Periscope Mirrors mounted in metal andplastic. Only plywood body frame is required to finish thisexceptional Periscope. First surface mirror is well pro-tected by glass windows. Set weighs 2-3/4 lbs. Overalllength of mount 6-1/8", width 21/8 . Would normallyretail at $40 to $50.Stock #700-W ................. $3.00 Complete Set PostpaidTWO SETS (4 UNITS) ...... S...... PECIAL $5.50 Postpaid

* SATISFACTION GUARANTEED

EDMUND SALVAGE COMPANY P.O. AUDUBON, NEW JERSEY

8

MAY 18, 1945 SCIENCE-ADVERTISEMENTS 9

BIi th OTei

/hi \.acieemn maksaote

Bmilstone in the r markae vitm o

complishe discove Mesrck Researcmade by Merck chemists and theircollaborators in vitamin research.

Pure Biotin is now commerciallyavailable. For the present, however,supplies of this newly synthesizedmember of the vitamin B complex arenecessarily limited.

PURE VITAMINS Merck & Co.jnc. now manufacturesall the vitamins commercially avail-able in pure form with the exception

-products of Merck Research of vitamins A and

Merck research has been directly responsible for many im-portant contributions to the synthesis, development, and 9large-scale production of individual vitamin factors in pureform.

In a number of instances the pure vitamins may be con.sidered to be products of Merck research. Several were origi-nally synthesized in the Merck Research Laboratories, andothers have been synthesized by Merck chemists-and collabo-rators in associated laboratories.

Because most of the known vitamins have now been madeavailable in pure form, effective therapy of specific vitamindeficiencies can be conducted on a rational and controlledbasis, under the direction of the physician.......

.MERCK & CO., Inc. A4 RAHWAY, N. J.

MAY 18, 1945 SCIENCE-ADVERTISEMENTS 9

SCIENCE-ADVERTISEMENTS

14 Sftee ae4e hamf

Guaranteed Vacuum.05 Micron-.00005 mm Hg

Free Air Capacity33.4 Liters Per Minute D UO-SE L

Greater free-air capacity andhigher ultimate vacuum assurefastest pumping at all pressures.

PUMPING SPEED14.9 Liters Per Minute at1 Micron at 304 R.P.M.

24.2 Liters Per Minute at1 Micron at 528 R.P.M.

Optimum Operating Speed

No. 1405-H 300 Revolutions Per Min.

Oil Required-650 ml Duo-Seal OilDUO-SEAL PUMP, Motor Driven. Vacuumto less than .05 micron and free air capacity of33.4 liters per minute ............... $140.00 s iI e n t

Also supplied with a larger motor giving 57 liters Opera t io n / e w1 P lfree air capacity per minute and a vacuum of0.1 micron ...... $155.00

THIS BOOKLETEXPLAINS ALL.

----Li Write for it today. Con-tains full details and dia-grams on Welch Pumps.

W. M. WELCH SCIENTIFIC COMPANYEstablished 1880

1517 Sedgwick Street Chicago 10, Illinois, U.S.A.Manufacturers of Scientific Instruments and Laboratory Apparatus. m

PI-

%. OOF

10 Voi.,, 101, No. 2629

4

--A

SCIENCE

VOL. 101 FRIDAY, MAY 18, 1945 No. 2629

Shall We Lose or Keep Our Plant and Animal nary Tract: PROFESSOR GEORGE N. PAPANICOLAOUStocks?., PRoFEssoR WALTER LANDAUER ........................ 497 and VICTOR F. MARSHALL. The Adsorption of

Thrombin on Fibrin: DR. WALTER H. SEEGERS,Disease of the Heart. DR. ALRED E. COHN .................. 499 MARIE NIEFT and EUGENE C. LOOMIS ............................. 515

Obituary: Scientific Apparatus and Laboratory Methods:Recent Deaths.........502 An Easily Assembled Machine for Making Cotton

Plugs for Culture Tubes: PROFESSOR ORTON K.Scientific Events: STARK. Microviscometer: DR. ELLow B. WEYER.The Argentine. Declaration; Behabilitation of the The Use of Double-Cycle A and B Scales on StraightPhysically Handicapped; The American Chemical Slide Rules: DR. CARLmON E. BROWN .................................... 521Society; The American Academy of Arts and

Sciences ..................................... 502 Science News.12

Scientific Notes and News ............50......... ......................... 504

Discussion: SCIENCE: A Weekly Journal, since 1900 the officialComparative Scientific Strength of Universities: organ of the American Association for the AdvancementDR. GEORGE GAYLORD SIMPSON. The Effect of of Science. Published by the American Association forMotion Pictures on Body Temperature: DR N. the Advancement of Science every Friday at Lancaster,KLEITMAN. Growing Rubber in Costa Rica: Pennsylvania.RAFAL W. KEITH.....................506 Editors: JOSEPHINE OWEN CATLL and JAQUES

Scientific Books: CATTELL.Individuality: PROFESSOR H. S. JENNINGS .................. 509 Policy Committee: MALCOLM H. SOuLE, ROGER ADAMS

and WALTER R. MLS.Reports: Advertising Manager: THEO. J. CHRISTNSEN.War Research at Mellon Inetituste, 1944-5: DR.W. A. AO.eR.t lR

Communications relative to articles offered for publicationshould be addressed to Editors of Science, 34 Gramercy Park,New York 3, N. Y.

Special Articles: Communications relative to advertising should be addressedCrystallization of Southern Bean Mosaic Virus: to THuro. CHRISTENSEN, Adveartising Manager, SmithsonianDR. W. C. PRICE. Inactivation of the Irritant Communications relative to membership in the AssociationToxicants of Poison Ivy and Related Compounds and to all matters of business of the Association should beby Tyrosinase: PROFESSOR IRWIN W. SIZER and addressed to the Permanent Secretary, A.A.A.S., SmithsonianCLEMENS E. PRLOKESCH. Urine Sediment Smears Institution Building, Washington 25, D. C.as a Diagnostic Procedure in Cancers of the Uri- Annual subscription, $6.00 Single copies, 15 cents

SHALL WE LOSE OR KEEP OUR PLANT ANDANIMAL STOCKS

By Professor WALTER LANDAUERTHE UNIVERSITY OF CONNECTICUT, STORRS, CONN.

GENETICISTS have teamed to produce hereditaryvariations at will; they have succeeded in multiplyinggreatly the frequency with which mutations occur;but they have not yet brought under control the di-rection of these events. The future may well hold thesecret of how to overeome the randomness of changesin the hereditary substratum of organisms, and we

may thereby master the fashioning of plants and ani-mals "according to plan." Until -this time has ar-

rived, however, we shall do well to keep in mind thewords of William Bateson, "Variation leads; thebreeder follows." The art of breeding, the art ofproducing new combinations of genes, rests entirelyon the raw materials-the mutations-as they are

provided by nature.

The uses to which new mutations and varied genecombinations may be put are manifold. Geneticistsand biologists generally seek material which will aidin an analysis of development and evolution. Stu-dents of human and veterinary medicine are inter-ested in those forms of life which are most likely tocontribute to the understanding and control of dis-ease. Breeders of livestock and of crop or ornamen-tal plants search for types which will enhance thepleasures and profits to be derived from their stocksby heightened disease resistance, greater vigor, in-creased yields or particular esthetic values. Thepresent war has dramatized the need of various in-dustries- for plant materials with specified qualities,many of which could not be obtained. Stocks which