belong in NEW KIMAX@Super-Strength Beakers

An accident at the crucial point couldmean lost time. Lost effort. NowKimble has strengthened the con-ventional beaker to insure againstthis costly loss. You can expect newKimax Super-Strength Beakers tolast 300% longer than the ordinarytype. Their longer life, greater accu-racy comes from the improvementsshown on the right.Kimax Super-Strength Beakers are

available in five sizes. Compare.You'll see how-good as conventionalbeakers are-the new ones fromKimble give you even more valuewith longer glass life at a competitiveprice. Orders can be assorted withthose for other Kimax LaboratoryGlassware to obtain maximum dis-counts available from most dealers.

Heavy,uniformsidewallsthroughout.

tmprovedwhite mattefinish foreasy marking,easy reading.

Heavy,tapered tops,

Graduationsaccurate to

±4-5% for fastpreparation

of solutions.

-lHeavier,j evenlydistri buted

radius atvulnerableheel area.

-j

OWENS-ILLINOISmaker of Kimble ProductsToledo 1, OhioI

30 AUGUST 1963 759

ANNOUNCING The Second Annual

SCIE:NCE GUIDE TO SCIENTIFIC INSTRUMENTS

to be published 8 November 1963

The 1963 edition of the SCIENCE Guide to Scientific Instruments will be the mostcomprehensive yet published. It will include over 2000 manufacturers of morethan 1200 different categories of scientific equipment. Now, for the first time, re-search workers in all fields of science will have readily available information onwhere to obtain instruments and equipment of all types.

HOW TO OBTAIN A COPYIf you are a subscriber to SCIENCE, you will automatically receive a copy. If you are not alreadya subscriber, you can start your subscription with this issue.

INFORMATION FOR ADVERTISERSAny manufacturer of scientific equipment is eligible for a listing. There is no charge for listing.

The guide will be distributed to all SCIENCE subscribers. Also, additional copies will be printedfor distribution to future subscribers. The guide will have a guaranteed distribution of over92,000. This assures virtually blanket coverage of every type of research laboratory. The regu-lar advertising rates for SCIENCE apply to this issue.

HOW YOUR PRODUCTS CAN BE LISTED

Over 5000 questionaires have been mailed to manufacturers of research instruments andequipment. However, if your company has not received a questionaire by 1 September, writeto the following address for application forms.

Science Guide to Scientific Instruments11 West 42 Street

New York, New York 10036PE 6-1858

SAMPLE OF CATEGORY LISTINGS

760 SCIENCE, VOL. 141

545. Cameras, High-Speeds StreakCameras, Kynlbgraph. See 2250Cameras, Microscope. See 3785

550. Cameras, Optically TriggeredCameras, Oscilloscope. See 3570,3575Cameras, Photomicrographic. See3785Cameras, Scintillation. See 3296

555. Cameras, Time-Lapse Motion Pic-tureCameras, Underwater. See 3420Cameras, X-ray Diffraction. See5400

(End of Cameras)560. Cans, Specimen Type for Biological

Samples565. Capacitance Measuring Equipment570. Capacitance Standards575. Capacitors, High-Voltage Storage580. Carbon Analyzers, Combustion

Type585. Carbon Analyzers, Organic Carbon590. Carbon Dioxide Analyzers, not

Van SlykeCarbon Dioxide Analyzers, VanSlyke. See 455

595. Carbon Hydrogen Analyzers600. Carbon Hydrogen Nitrogen Ana-

lyzersCarboys, Plastic. See 3855

605. Cardiac Flow Systems610. Cardiac Monitors615. Cardiotachometers620. Carts, Laboratory621. Catalytic Reaction Apparatus625. Catheters, Intradcardiac630. Cathetometers

Cell Disintegrators. See 1355, 1360635. Cell Fractionaters, Biological

Cells, Battery. See 370Cells, Colorimeter. See 965Cells, Conductivity. See 1070Cells, Electrophoresis. See 1490Cells, Fuel. See 1816, 1817Cells, Liquid Chromatography. See835Cells, Nephelometer. See 2875Cells, Photoelectric. See 3750-3760

636. Cells, Quartz, for Liquid SamplesCells, Spectrophotometer. See4605, 4610

Centrifuges

640. Centrifuge Tubes, GlassCentrifuge Tubes, Plastic. See 3860

645. Centrifuges, Angle Head650. Centrifuges, Basket655. Centrifuges, Chromatographic, Pa-

per Strip660. Centrifuges, Continuous Flow665. Centrifuges, Explosion-Proof670. Centrifuges, General-Purpose, 1200

to 4500 rev/min675.. Centrifuges, Hematocrit680. Centrifuges, Microchemical685. Centrifuges, Refrigerated690. Centrifuges, Super-Speed, for Liq-

uid SeparationCentrifuges, Ultra. See 5180

695. Centrifuges, Ultraspeed

ChamberS, Environmental, Animal.See 156Charts, Absorption Spectra. See 5Charts, Bacteriological. See 215Charts, Emission Spectra. See4555

705. Charts, Periodic TableCharts, Radioactive Decay. See2965Charts, Recorder. See 4220-4223

710. Chemical Analyzers, Automatic(for sampling and preparation)Chemicals, Isotope-Labeled Com-pounds. See 3145Chick Heart Monitor. See 2035

715. Chloride Meters

Chromatography, Gas

720. Adsorbents, Solid725. Attenuators, Automatic730. Chromatographs, Gas, Argon Ioni-

zation DetectingChromatographs, Gas, Blood GasAnalysis. See 440

735. Chromatographs, Gas, CoulometricDetecting

740. Chromatographs, Gas, ElectronAffinity Detecting

.745. Chromatographs, Gas, Flame loni-zation Detecting

750. Chromatographs, Gas, PreparativeType

755. Chromatographs, Gas, ThermalConductivity Detecting

760. Column Packing765. Columns, Golay770. Columns, Packed775. Contour Measuring Projectors780. Detectors, Ionization785. Fraction Collectors, Gas

Gas Sampling Devices. See 810,826Hydrogen Purifiers. See 2130

790. Integrating Recorders795. Integrators, Digital Readout800. Integrators for Strip-Chart Re-

cordersLiquid Sampling Devices. See 830

805. Pyrolysis Apparatus for Sampling806. Stationary Liquid Phases807. Supports, Solid810. Syringes for Gas SampIe Introduc-

tion815. Temperature Programmers820. Tube Fittings825. Valves, for Column Switching826. Valves for Sampling Gas830. Valves for Sampling Liquid

(End of Chromatography, Gas)

Chromatography, Liquid

833. Adsorbents, Solid835. Cells, Flow Through840. Chromatograph Tubes, Glass845. Chromatograph Tubes, Plastic,

Disposable850. Column Monitors, Fluorescent855. Column Monitors, Spectrophoto-

metric, for Optical Density860. Fraction Collectors865. Gradient Mixers870. Ion-Exchange Crystals875. Ion-Exchange ResinsS80. Solvents

(End of Chromatography, Liquid)

Chromatography, Paper

890. Chromatographs, Paper895. Densitometers900. Desalters

Dialyzers. See 1300905. Drying Ovens906. Indicator Sprays907. Ion-Exchange Paper908. Filter Paper910. Scanners, Photoelectric

Scanners, Radioisotope. See 2970915. Scanners, Ultraviolet, Fluorescence920. Viewing Cabinets

(End of Chromatography, Paper)925. Chromatography, Thin Layer926. Chromatography, Thin Layer, Ad-

sorbents927. Chromatography, Thin Layer, Ap-

plicators930. Chromatography, Thin Layer,

Densitometers935. Chromatography, Thin Layer,

Fluorescence940. Cineradiographic Systems945. Clamp and Rod Systems for Glass-

ware950. Clean Room Furniture955. Cleaners, Glassware, Detergents

Cleaners, Ultrasonic. See 2010Closed-Circuit TV. See 4840Cloud Chambers. See 2975Cobalt Sources. See 2985

959. Collimators, Optical960. Colony Counters, Bacteriological965. Colorimeter Cells970. Colorimeters, Photoelectric Ab-

sorption975. Colorimeters, Reflectance

Column Fractionators, DensityGradient. See 1220Column 'Monitors, Liquid Chro-motography. See 855Column Packing. See 760

980. Combustion Boats985. Combustion Furnaces, High Fre-

quency Induction990. Combustion Furnaces, Tube Type995. Combustion Trains, Micro

1000. Combustion Tubes1005. Combustion Units, Schoeniger Type

Comparators, Film. See 1636, 1637Comparators, Optical. See 3555

1010. Compression Testors, Hand-Oper-ated

Computing Equipment1015. Computer Teaching Equipment (for

theory)1020. Computers, Analog1025. Computers, Biological, Special-

Purpose1030. Computers, Digital ($125,000 and

under)1031. Computers, Digital (over $125,000)1035. Data Converters, Analog-to-Digital1036. Data Converters, Binary-to-Decimal1040. Data Converters, Digital-to-Analog1045. Data Reducers, Shaft-to-Digital1050. Data Reducers, Voltage-to-Digital1055. Encoders, Shaft-to-Digital1060. Paper Tape Readers

(End of Contputers)1065. Conductivity Bridges1070. Conductivity Cells1075. Conductivity Meters

761

700. Centrifuges, Vacuum(End of Centrifuges)

Chambers, Acoustic. See 30Chambers, Altitude. See 57Chambers, Atmospheric. See 1590

30 AUGUST 1963

For Photomicrography ...Macrophotography... Gross PhotographyThe Leitz Aristophot is a universal laboratory cam-era. It masters all laboratory photographic tasks. Ina matter of minutes, the Aristophot lets you changefrom micro to macro or to gross photography. Youhave the choice of 35mm, 31/4 ¼"x41/4" or 4" x 5"in both conventional or Polaroid, as well as highlyprecise motion-picture and time-lapse photography.

Write for complete details and specifications. Illus-trated brochure shows how Aristophot can be usedwith your microscopes and how it integrates withLeitz microscopes, including the famous Leitz uni-versal research microscope, Ortholux, with its ownlight sources, or Xenon and high-pressure mercurylamps for special applications. 47063

E. LEITZ, INC., 468 PARK AVENUE SOUTH, NEW YORK 16, N. V.D s t r b u t o r s o f t h e w o r I d - f a m o u s p r o d u C t s o fErnst Leitz G. m. b. H., Wetz lar, Germany-Ernst Leitz Canada Ltd.LEICA AND LEICINA CAMERAS * LENSES - PROJECTORS MICROSCOPES

SCIENCE, VOL. 141764

WHAT'SNEW

IN THENEWESTTRI-CARB

SPECTROMETERS?-Eu-..-

everything !*13-dynode photomultiplier tubes with signalpulse summation for highest efficiency andbest isotope separation.

* Rugged, "light-lock" detector assembly withnew graded shielding and high-speedsample loading.

*Fast coincidence circuitry with wide dynamicrange for best performance.

*Completely separate channels (two or three)of pulse height analysis for optimumchannel selection.

*Precision gain control and fast-recovery linearamplifiers for greatest accuracy.

*Highly stable and linear pulse.heightanalyzers for best operation with fast liquidand slow crystal pulses (switch selection).

*High-speed (20 megacycle) scalers within-line, numerical display for greatestcounting accuracy and best legibility.

*Built-in automatic background subtractionfor convenience and for accuracy of ratioscalculated automatically.

*Low activity sample reject to save valuablecounting time where many samples containno material of interest.

1Highest quality digital printers or calculatorsfor fastest and most reliable data presentation.Compact console designs to take minimumfloor space and no bench space.

|Pc3kckrcI PACKARD INSTRUMENT COMPANY, INC.BOX 428 * LA GRANGE, ILLINOIS,, AREA CODE 312- 485-6330

The incomparable new 3000 and 4000 SeriesTri-Carb Liquid Scintillation Spectrometers em-body more than a score of major design andoperating improvements. The result: sensitivity,accuracy, and reliability of a degree never beforeachieved in liquid scintillation counting equip-ment. These ultra-modern instruments are avail-able in configurations and with capabilities tomatch any research budget or counting require-ment. Your Packard Sales Engineer can providecomplete details and performance data. Write forillustrated Bulletin.

SCIENCE, VOL. 141766

PHOTOMICROGRAPHYThe new Honeywell Model 52A Stro-.bonar Electronic Flash Unit is a ver-satile and economical light source forall types of photomicrography, blackand white or color.

Concentric with the electronic flashtube is an incandescent light withwhich the unit is positioned for cor-rect light reflection. Users report in-tensity of flash is excellent even atmaximum magnification. Absence ofheat protects specimens from physicalchange and warping.

A universal bracket fits the uInit formany assignments in both laboratoryand field. The 52A can be flashed byany camera synchronized for elec-tronic flash. Specify: Model 52A Stro-bonar Electronic Flash; 11OV-AC, 90Watts; 16 ft. cord; 3 lbs.; 8'x4'2"x5'.

For illustrated folder on the 52A StrobonarElectronic Flash, please write: DavidMoore, Mail Station 209, Honeywell,Denver Division, Denver 10, Colorado.

HoneywellPHOTOGRAPHIC PRODUCTS

Lively and continuing discussionstook place as the delegates joined in theexploration of the highly involved inter-actions of plant roots, soil, saprophyticsoil microorganisnms, and plant patho-gens. The ultimate objective of thesymposium was the subjugation by bio-logical means of soil-borne pathogenicviruses, bacteria, fungi, and nematodes.In essence, this was a search for newapproaches and new ideas on how toattain control of such groups of soil-borne plant pathogens through biolog-ical techniques and an attempt to definethe areas where additional research ismost needed.The underlying encouragenment which

motivated the symposium has comefrom instances of biological controlwhich have proven successful and,nmore than this, sometimiies spectacular.This has been especially true wherechemical control has not been economl-icallv feasible and suitable resistant va-rieties of plants have not been available.One of the oldest biological ap-

proaches to control disease on pathogen-infested land has been to resort to dif-ferent crop successions or to turn undervarious green manure crops to allaydamage fronm diseases anticipated in asucceeding crop. This technique has metwith notable success in certain regionsagainst specific diseases. For example,it is reported that phymatotrichumll rootrot of cotton in the Southwest is beingsuccessfully conmbated by disking intothe soil an immature crop of peas in thespring, prior to planting cotton. Ophio-bolus root rot ("take-all") of wheatnmay be controlled by rotating a crop ofoats with the wheat.

In California streptomyces scab ofpotato is effectively kept in check wherethe crop is grown on the same land yearafter year by growing a crop of soy-beans in the fall after the potato harvestand turning it under before the cropnmatures. Sclerotium rot of peanuts isprevented in the South by avoiding thepresence of undecomposed organic lit-ter in the top few inches of soil. Aserious Fomes rot of rubber tree crownsand roots in the tropics is being keptunder control cheaply and rather spec-tacularly by biological means. A partic-ular variety of legume is grown as aground cover in rubber plantings wherethe disease has appeared. The pathogenappears to dissipate its energy on thelegume without doing any real danmageto either the legume or the rubbertrees.On the other hand, many crop rota-

tion and cover-cropping systems either

836

fail in disease control or actually makethe disease worse.An objective of the symposium was

to seek out the mechanismiis involved inbiological control in soil and to under-stand the circumstances which make forsuccess on one hand and failure on theother. Knowledge of the mechanismiisinvolved in the soil-pathogen-host rela-tionships would enable a more intelli-gent approach to the control of soil-borne diseases through biologicalmeeans.Several aspects were selected for great-

er research emnphasis. It was broughtout, for instance, that the behavior ofthe host plant in terms of root diseasesmay be nmanipulated to some extent bysprays, fertilization, time of planting,and so forth. Since root exudates areknown to be imlportant in initiating theactivity of root parasites, it follows thatcultural practices which influence theanmounts and quality of these exudatesare important in the inception of dis-ease and in its avoidance.

Since mlost pathogens in soil are in aresting rather than a vegetative condi-tion, it is clear that the nmanipulation ofsoil likewise may be important. Moreinformation is needed on the factorswhich influence the survival, multipli-cation, aind parasitic activity of thepathogens in soil. Stimulltion of thepathogen into activity in the absence ofits host miayv waste the reserves of theorganisiii and decrease its population insoil. Certainly it becamle clear that thespecific roles of plant exudates andplant residues in nature need clarifica-tion.

MIany discussions centered about therole of natural openings in roots inrelation to pathogen entry. Ruptures atthe point of root emergence, the senes-cence of transient roots, and certainfeatures of the root surfaces themselveswere considered as possible portals ofentry. It is surprising how little informna-tion is available on root anatomy andphysiology in relation to pathogen entryand development.

Investigoators from different disci-plines were nmade aware of the overallproblenms in the biological control ofroot diseases and most had valuablesuggestions to offer.

Critically deficient lacunae in ourknowledge of the interactions of soil,plant, and soil microorganisms in rela-tion to the activity of root pathogenswere pinpointed.

It became apparent that although bi-ological control, as treated here, couldbe and at times is accomplished by di-

SCIENCE, VOL. 141