Speedomax Recorder and a fewof the parts for its circuit-balance-motor drive. You'll findthe same rugged constructionthroughout the instrument.

RIGID CONSTRUCTION MEANSRig4Ddak&tql

* When you turn a measuring or control job overto a Speedomax iinstrument, much of the good per-formance vou receive is due to the strong, carefully-assembled mechanism controlled by the sensitiveelectronic circuits. Seasoned, time-proved mechani-cal design is evident as soon as you open the instru-ment door.

For instanice. just rotate the "big" balancing-geartrainl withi your fingers. You won't detect back-lash.The traini will turn at a touch, but those two l"face, spriing-loaded gears are held so snugly againstthe pinlioins, in opposite directions, that they answerevery ti!iy balainciing motion in either direction. Theslightest nudge fromn the "huge" 12-watt balancingmotor therefore goes straight to the slidewire, re-cordiing and cointrol mechaniism via their commonshaft. The tying of these functions to one shaftassures permianenit alignment of recording, controland measuring! funictions.The paper drive and some other components get

their positive actionl in another way. They usemachined, heat-treated worm gearing for snug fitand precise motion. Ability to use such designs isone of the many advantages of the instrument'sample power. Liberal use of ball bearings is anotherquality feature, to transmit full power, reduce routineattention and maintaiin operating precision.As you look further into a Speedomax, you'll also

note that many parts such as frame castings, shafts,linkages, etc., seem very large. But there's a strong

reason for this seeming oversize- - it prevents me-chanical deflections in operation. Rigid constructiongives rigid dependability.

Additional 'Contacts Hern

Balancing

NMotor

o Fo

Boall

Bearings

-Loading Springs

38" Shaft

Space For Many.Signalling And

Control Contacts

Measuring Slidewire-+

The Speedomax Mechanism "Heart" Is Just 2 Assemblies

Why not inspect these and other evidences ofquality the next time you need an electronic potenti-ometer or bridge. You can easily check them againstthe general description in our Catalog ND46(1). Ifyou're interested in research, ask also for TechnicalPublication ND46(1). Address our nearest office, or4926 Stenton Ave., Philadelphia 44, Pa.

I NLEEDS NORTHRUPinstruments automatic controls * furnaces

Jrl A(d ND46(11

New (5th) Edition! Frobisher-Fundamnentals of Microbiology

Dr. Frobisher's emphasis on sound, broad and unspecialized teaching funda-mentals has earned for this text (formerly "Fundamentals of Bacteriology") anoutstanding position in its field. The material is for undergraduate students andis written in a style that has caused the book to be called a "model of textbookwriting". The text has been completely reorganized, rewritten and modernized forits New (5th) Edition, reflecting every recent advance in the field. Material onthe physiology and genetics of microorganisms is especially worthwhile, and thecomprehensive information given in three chapters on Metabolism of Micro-organisms highlights the book.By MARTIN FROBISHER, JR., Sc.D., Professor and Head of the Department of Bacteriology, University ofGeorgia; Associate Professor of Bacteriology, Emory University; Visiting Lecturer, Johns Hopkins Uni-versity; Special Consultant, U. S. Public Health Service. 633 pages, 6" x 9", 253 illustrations-some in color.$6.00. New (5th) Edition!

A New Book!Braun-Bacterial, Geneties

This much-needed new book covers the progress made in the increasingly im-portant field of bacterial genetics. Its aim is to make principles and currentfindings in this area readily understandable to bacteriologists and to researchworkers and students in genetics. Beginning with a review of the principles ofgenetics, the text goes on to provide a basis for better evaluation of the relation-ship between bacterial genetics and such diverse problems as pathogenesis,general laboratory techniques, bacterial physiology, epidemiology, therapy andtaxonomy. Compact and simplified, this book is also excellent for courses inGenetics of Bacteria.By WERNER BRAUN, Ph.D., 244 pages, 6" x 9", illustrated. New!-Ready in July.

W. B. SAUNDERS COMPANYWest Washington Square Philadelphia 5

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:1IiFfiI1LIL1a5TELESCOPEEXTEO AMAZING! POCKET COMPARATOR o- '; \

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SCIENCE, VoI. 1182

AMINO ACIDShydroxyglutamic acidhydroxy-L-proline

D isoleucineDL-isoleucineL-isoleucine

DL-lanthionineD leucineDL-leucineL-leucine

DL leucyl-glycineL leucyl-glycine

DL leucyl-glycyl-glycineL leucyl-glycyl-glycineD leucyl-L-tyrosineL leucyl-L-tyrosine

DL-lysine HydrochlorideL-lysine Hydrochloride

D-methionineDL-methionineL-methionineDL-norleucineDL-norvaline

DL-ornithine HydrochlorideL ornithine dihydrochloride

D-phenylalanineDL-phenylalanineL-phenylalanine

L-prolinesarcosineD-serineDL-serineL-serine

Sodium glutamatetaurine

DL-threonineL-threonineDL-thyroxineD-tryptophaneDL-tryptophaneL-tryptophaneDL-tyrosineL-tyrosineDL-valineL-valine

See Science June 26 issuefor additional listinzgs

IA READY REFERENCE)That will Save Time for You B/|

Use this catalog as a "one stop" source *sA*CHof Amino Acids, Vitamins, Carbohydrates, |Adenylates, Nucleates, Purines, Pyrimi-dines, Tetrazolium Salts, Enzymes, Micro-biological and Bacteriological Media, WRITE FORComplete Animal Test Diets and YOUR COPYIngredients for investigational use. TODAY

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

I

The OriginalUGLUNlETRIC

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Constant volume (1 to 25 c.c.) per sample-not possible with drop counter, as dropsize changes. An illuminated glass cylinderis filled to the level of a phototube which isadjustable in height. The phototube actu-ates a mechanism which opens a glass ballvalve and empties the cylinder.

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Special models available.

Please send for further data.

It¶3TJ1 714 Market PlaceMADISON 3, WIS.

SCIEN-CE, Vol. 118

A

4

Roo. U. S. Pat. OfF.

The RecoCHROMATOGRAPHYDRYING OVENA mechanical convection ovendesigned for heating paperchromatograms.

The RecoELECTRIC

DESALTERFor the removal of inorganicsalts from organic and aminoacid solutions to be chromat-o,raphed.

[RACKSStainless steel or glass for one

I ~~~~di mensional chromatography.

INDICATOR SPRAYSFor application of indicators to

l // \ ~chromatograms.

i | CLIPS KAll stainless steel spring clips for

| [ holding chromatograms to glass rods J

l ~~SOLVENT TROUGHSFor use in chromatocabs

I ~ -----~~'__or one-dimensional racks.

I ALSO AVAILABLE:

I Densitometers A General Cataloguefor quantitative deter- of the RECO Line ofminations on paper

I Utraviolet Lamps Paper PartitionI ro ni;.., rhk.mhhre Chromatographic

II

ry[CA ulb; UlldlllUtclbMicro PipetsChromatocabs

Equipment IsAvailable on Request.

KLETTELECTROPHOR ESIS

(

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.

July 10, 1953

WINTHROP

ASPARTIC ACIDCALCIUM IODOBEHENATECHLORACETOPYROCATECHOLCHOLINESTERASEDIETHYLACETAMIDOMALONATE5-DIETHYL-2-AMINOPENTANEGASTRIC MUCINGITOXIN

For the rest of the WinthropAlphabet send for 1953 Price List

Special Chemicals Division

INC.

1450 Broadway, New York 18, N. Y.

GARCEAU ELECTROENCEPHALOGRAPHS 1 S C HA.C. Operated No Batterles SCHOTT-JENA

Inkless Writing Require no ShieldlngShipped Ready to Run Prompt Delivery I Bacteria

Fritted Glass Filtersin crucible and, funnel form (Buechner Type)Filters of crucibles and funnels are made of Schott G-20 glass

~~~~~~~~ ~~~~~~and are tested by a new and improved method, assuring uniformpore measurement. Are free from antigenic substances. Do not

2. alter pH of solution filtered. Loss of solution is very small. Incrucible and funnel form. Available in 3 groups: G, coarse (3 to1.7 microns); M, medium (1.7 to 1 micron); F, fine (under 1micron).

Slit-sieve Funnels (Buechner Type)Slit-sieve funnels have narrow elongated slitholes. Made of Schott G-20 clear glass, havinghigh thermal durability and extreme resistanceto acids and alkalies. Being transparent, anyresidue within funnel can readily be seen. Per-

THE JUNIOR GARCEAU mits quick filtration. Plain surface prevents tear-ELECTROENCEPHALOGRAPH ing of filter paper. Easily cleaned.

A simplified inexpensive instrnment for recording electrical At laboratory suppliers, or from us.potentials of the brain. Built-in interference eliminators _per.mit use anywhere. Inkless records-no photography or film- * MADE IN WESTERN GERMANY *develo mt ,erequired. Instantaneous localization with any Write for bulletins SBF-342 and SFS-3432 of tdem 10 las. Price $575.00 complete.All Garceau Electroencephalographs operate en- FISH-SCHURMAN CORPORATIONtirely from the 115 volts 50 or 60 cycle power lines. 74 Portman Road, New Rochelle, N. Y.

ELECTRO-MEDICAL LABORATORY, INC.

6 SOUTH WOODSTOCK 2, VERMONT118

6 SCIE-NCE, VOl. 1 18

LOWEST PRICESON

"Corning" Brand

COVER GLASSESTHE WORLDS FINEST

Read what one of the largest fabricators ofcover-glasses in the country has to say about"Corning" Brand cover glass.

"In all of our experience in processing sheetcover glass of various manufacturers, bothforeign and domestic, for the past 25 years, the"Corning" glass is by far the best glass everproduced anywhere in the world. For color, uni-formity in thickness, freedom from imperfec-tions, flatness and resistance to corrosion it is ina class by itself."

This fine glass is the product of years of research anddevelopmew* of optical and laboratory glassware byCorning Glass Works whose name is synonymous withquality.

Effective at once the following new low pricesapply to "Corning" Brand Optical cover glass.

PER. OZ. PER. OZ. PER. OZ. PER. OZ. 150 ORCAT NO. DESCRIPTION SIZE LESS THAN 10-49 50-99 10-149 MORE

10 OUNCES OUNCES OUNCES OUNCES OUNCES

12mm 2.74 2.47 2.33 2.19 2.0673730 SQUARES #1 15mm 2.55 2.30 2.17 2.04 1.91

18-22-25mm 1.96 1.76 1.67 1.57 1.47

12mm 2.30 2.07 1.96 1.84 1.7373710 SQUARES #2 15mm 2.05 1.85 1.74 1.64 1.54

18-22-25mm 1.64 1.48 1.39 1.31 1.23

SMALLER THAN

737170 RECTANGULAR 1200 Sq. mm 1.96 1.76 1.67 1.57 1.47#1N 1200to 1500 1.98 1.78 1.68 1.58 1.49

?500 to 3750 2.52 2.27 2.14 2.02 1.89

SMALLER THAN

73750 RECTANGULAR 1200 Sq. mm 1.64 1.48 1.39 1.31 1.23#2 1200 to 1500 1.66 1.'49 1.41 1.33 1.25

1500to3750 1.98 1.78 1.68 1.58 1.49

12mm 4.80 4.32 4.08 3.84 3.6073781 CIRCLES #1 15mm 4.46 4.03 3.80 3.57 3.34

18-22-25mm 3.43 3.09 2.92 2.74 2.57

12mm 4.03 3.62 3.43 3.22 3.0373780 CIRCLES #2 15mm 3.59 3.24 3.05 2.87 2.69

18-22-25mm 2.87 2.59 2.43 2.29 2.15

PRICES SUBJECT TO CHANCEAAAAA

LABFRATUOK AM7VAKATUU - REAEINTI AU CflENICALS

July 10, 1953

I

qn}

7

NATURAL

@0with the finest

optical system ever produced

for wide field work

You want distortion-free magnification

of the object... you want the image to be

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lief also, the image should be erect

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scopes, the world's unequalled standard

for 3-dimensional microscopy, PLUS:

~~~Full critical coverage of wider

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Dustproof prisms and nose-

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of the instrument

* Shockproof construction, for

year after year of hard,

on-the-lob use.

WRITE for informative 24-page cat-alog, and for a practical demonstra-

tion. Bausch & Lomb Optical Co,

64242 St. Paul St., Rochester 2, N. Y.

-:IIlIMj4 E.u q?.] iii i.) (.J fI'j.] iii [4 ieM?('I I*

IAUSCH LlOMI CENTENNIAL

SCIENCE, Vol. 1188