SCIENCE 9

ORGANIC SYNTHESES, Volume 29Cliff S. Hamilton, Editor-in-Chief. This new volume continues the high standards of the Or-ganic Syntheses Series by bringing the chemist 26 new syntheses, each thoroughly checked andfully described. In addition to introducing important new processes, the volume serves as asource of preparative technique. Among the new syntheses covered are: Acrylic Acid; 1-Acetyl-cyclohexane; Catalyst, Raney, Nickel; 2-Chloromethylthiophene; Homophthalic Acid and Anhy-dride; and Protocatechuic Acid.Ready in December Approx. 122 pages Prob. price $2.50

THE CHEMISTRY OFORGANIC MEDICINAL PRODUCTSThird Edition. By Glenn L. Jenkins and Walter H. Hartung. Complete information onnomenclature, occurrence, preparation, structural formulas, properties, trade names, andphysiological activity of the organic compounds important in pharmacy and medicine can befound in this new edition. New sections have been added and others rewritten on such sub-jects as Antibiotics, Antimalarials, Sulfonamide Compounds, Aminoacids, Antihistaminic Drugs,and Enzymes. Typical methods of synthesis of important compounds are emphasized.3rd Edition, November 1949 745 pages Illus. $7.50

INTRODUCTION TOTHEORETICAL AND EXPERIMENTAL OPTICSBy Joseph Valasek. This book provides a close correlation of optical theory and experiment bycombining the principles of geometrical and physical optics with experiments in optics andspectroscopy. In addition to theory and experiment, the book also treats the applications ofoptics in such fields as optical instruments, photographic optics, opthalmic lenses, interferometry,photoelasticity, spectrochemical analysis, and x-ray spectroscopy. The four sections of the bookcover geometrical optics, physical optics, radiation and spectra, and experiments.October 1949 454 pages 218 illus. $6.50

TRILINEAR CHART OF NUCLEAR SPECIESPrepared under the direction of William H. Sullivan. A multicolor graphic presentation ofdata on all experimentally identified nuclear species known by approximately June 1949. Theportfolio contains 6 separate charts, 36" by 11". When properly assembled, the chart presentson a single continuous strip, the systematics of and physical constants data for these nuclearspecies or nuclides. Each hexagonal figure representing one nuclide holds such data as relativenatural isotope abundance, atomic mass, angular momentum, and percentage of radiation.November 1949 6 charts with instructions and cover $2.50

mbedd

SCIENCE ~.9November 25. 1949, Vol. 110

10SCECNoebr2,14,Vl11

REGISTER NOWfor the New York Meeting of the AAAS

AVOID CONGESTION AND DELAYGET YOUR GENERAL PROGRAM

EARLY IN DECEMBER

Registration in advance of arrival at the 116th Annual Meeting of theAAAS in the Pennsylvania Zone hotels of New York City, December 26-31,1949, has-,so many advantaWge that we wonder why almost-:evergone doesn'ttake this simple step. For instance:1. You avoid eongestion and delay at the Registration Desks in the hotel

foyers. All indications point to a record-breaking attendance since allof the Association's seventeen sections and subsections, and more thanfifty societies, will have sessions; also this is the first meeting in NewYork City since 1928.

2. You receive the General Program early in December in ample time un-hurriedly to decide among the events and the sessions of the societiesthat you wish to attend.

3. Your name and hotel address will be in the Visible Directory the firsthour of the first day of the meetings, since it will be posted in Washing-ton as soon as processed.

4. Advance Registrants will have the same privileges of receiving a mapand directory of points of interest of New York City, literature, radiobroadcast tickets, etc. At the convenience of Advance Registrants, thesewill be distributed from the Main Registration on the Penn Top of theHotel Statler, the location of the Annual Science Exposition, the VisibleDirectory, and the Science Theatre. Admission to the excellent seriesof latest scientific films will be free to all Registrants.

This year, as a result of the vote of the biological societies, includingthe American Society of Naturalists, the sponsors, the Biologist'Smoker will be open only to regular registrants or those who pay a

registration fee at the time.

_ THIS IS YOUR ADVANCE REGISTRATION COUPON1. Registration Fee enclosed: (cheek one)

o $2.00 A.A.A.S. Member D $2.00 College. Studento $2.00 Wife (or, H-unband) of Registrant []$3.00 Non-member of A.A.A.S.

2. FULLNAME(Miss,Mrs., Dr., etc.) .................. ......... ........

(Please print or typewrite) (Last) (First) (Initial)3. ACADEMIC, PROFESSIONAL OR

B U SIN E SS C O N N ECTION ........................... ........................ ............................................................................................................... ........ ......

4. OFFICE OR HOMEADDRESS........................ . ... .... ........................................................................

(For receipt of Program and Badge)

5. Y O U R F IE L D O F IN TEREST .......................................... ...................................................... ..................................................................................

6. C O N V E N T IO N ADDRESS ..................................................................................................................................................................... ...........

(If not known now may be added later)

7. DATE OF ARRIVAL ................... ....... DATE OF DEPARTURE.Please mail this Coupon and your check or money order for the fee, $2.00 or $3.00, toTHE AMERICAN ASSOCIATION FOR THE ADVANCEMkENT OF SCIENCE

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

10 SCIENCE November 25, 1949, Vol. 1 10

November 25, 1949,VoL110SCIENCE 11~~~~~~l

H'OTEL R'E'SERVATIONS116th AAAS MEETING

New York City, December 26-31, 1949The list of hotels and the reservation coupon below are for your convenience in

making your hotel room reservation in New York City. Please send your application,not to any hotel directly, but to the Housing Bureau of the New York Convention andVisitors Bureau to avoid delay and confusion. The experienced Housing Bureau willmake assignments promptly and the hotel will send a confirmation directly to you intwo weeks or less. Mail your application now to secure your first choice of desiredaccommodations.

HOTELS AND RATES* PER DAYHOTEL** WITHOUT BATH WITH BATH Twin 3 4

Single Double Single Double Beds Beds Beds

STATLER $4.00 $6.50 $8.00 $11.00 $13.0047.50 -$10.50 -$14.00

NEW YORKER $4.50 $7.00 $8.00 $9.50 $12.00410*00 -$13.50 -$13.50 -$-10.50 -$14.00

MCALPIN $3.00 $5.00 $4.00 $6.50 $7.50 $9.50 $14.00-$3.50 -$5.50 -$7.00 -$10.00 -$11.00 -$12.00 -$17.50

GOVERNOR -LINTON $4.00 $6.50 $7.50 $10.50 $12.00-$6.00 -$8.00 -$9.50

MARTINIQUE $2.50 $5.75 $3.75 $6.00 $6.00 $9.00 $11.00-$3.00 -$5.00 -$8.00 -$8.00

Suites range from $10.00 to $26.00; $10.00 to $18.00 at Martinique, $12.00 to $22.00 atNew Yorker, $12.50 to $26.00 at Governor Clinton, $13.00 to $16.00 at McAlpin, and$15.00 to $17.00 at Statler.The New Yorker charges $2.50 for an additional person per room; the other hotels $2.00.

* New York City Hotel-room Tax of 5% is not included in this schedule of rates.** A Ust of the headquarters of each society appeared in THE SCIZNTIrIC MONTHLY for August,

pages iv and v, and in Association Affairs, SCIENCE, August 26, page 220.

_ - -- - - THIS IS YOUR HOTEL RESERVATION COUPONMiss Sylvia T. Peltonen, ManagerHousing BureauNew York Convention and Visitors Bureau Date of application.500 Park AvenueNewY;York 22, N. Y.

Please reserve the following accommodations for the 116th Annual Meeting of the AAAS:TYPE OF ACCOMMODATION DESIREDSingle Room ....... Rate ..

Double Room.Rate .................. Numberin Party.Other.Rate ............ Sharing this room will be:hr .................................................................. Ra e ..... ................................................................ Sh ri th ro

......................................................persons.......................(Enumerate and attach list giving names and addresses of each person, including yourself)CHOICE OF HOTELFirst choice .... ............ Second choice . ......... Thirdchoice .

DATE OF ARRIVAL. ......... DEPARTURE DATE .

(These must be indicated)SIGNED .............

A D D RESS ....................................................................................................................................................................................................................(Street) (City and Zone) (State)

Mail this now to the Housing Bureau.Rooms will be assigned and confirmed in order of receipt of reservation.

Hotel will confirm directly in two weeks or less.

November 25, 1949, Vol. 1 10 SCIENCE 11

SCIENCE November 25, 1949, Vol. 1:10

PHOTOMICROGRAPHY° fit VISICAM'

A New-Style Reflex CameraUnit for Photomicrography . ._the VISICAM can be attached_to monocular or binocularmicroscopes. The built-in shutter pro-vides time exposures in automaticspeeds of I to 1 /1 00 sec-onds. The VISICAM usesstandard Argus 35-mm. orCamro Bantam size backs.A 2-inch ground-glass view-ing screen is provided witha black-line frame for delin-eating the 35-mm. field. The'Single-Shot Back' enablesshooting of individual 35-mm. frames. The VISICAMfits the modest budget!

Visicam shown in placeWrite for complete literature today!

ERB & GRAYSPEC

SCIENTIFIOINST1

.IALISTSmC & OPTICALRUMENTS

m

854 So. Fguaeroa St.Los Anglebs 14, Calif.

n a cL.w a

/4csmdIMPROVED HESS BLOOD VISCOSIMETER

Completely redesigned to provide greetr impictand ease of operation, the Helige Viscome toh firtAmerican-made instrument to off Improvements in tOHe Shlood Viscosimeter which asure determination ofgreater accuracy tan were obtainale in the pt.COMPLETE, $45.00 WRITE FOR CATALOG No. 1200

H EL LIG EIN CO RP ORATE D

3738 NORTHERN BLVD. LONG ISLAND CITY 1. N.Y.

A Trade MarkFor Scientific Animals?

One purpose of a trade mark is protection forthe buyer. It identifies a product that meetscertain standards agreed on by both buyer andsupplier.

Our various strains of mice, rats and guineapigs all carry the identifying initials "CF"-Carworth Farms.

This is your assurance of carefully bred animalsfor experimental research. CF strains have beenused for many years by leading laboratories withcomplete satisfaction.

Your inquiries are invited.

a.

FOR LATEST AUTHORITATIVEREVIEWS ON LABORATORY

PROCEDURES

A monthly publication comn.piled: for laboratory direc.tors, technicians and physi..cians. Full of essential factsand reviews of current literature on labora.tory procedure, professionally edited by R.B. H. Gradwohl, M. D., Sc. D. A neces-sity in the modern laboratory. Published by

flNINIAIAIIISCHOOL OFlikilhI~l~flILABORATORYGRADWOIIVU~l TECHNIQUE

3514 Lees Av. St. Louis, Mo.

I

I

12 SCIENCE November 25, 1949, Vol. 1,10

November 13

Potassium Biphthalate, C. P., A. C. S. is one of severalhundred different reagents which we manufacture. C & BReagents meet definite standards of purity-standardswhich are adequate to insure products suitable for re-search and analytical use.

C & B Products are distributed byLaboratory and Physician Supply Houses

throughout the World

Write for copy of catalog. The COLEMAN & BELL Co.Manufacturing Chemists, Norwood, 0., U.S.A.

'(tR!EIi ispTHE CARVER LABORATORY

Especially Fittedfor PressingPlant and

Animal Tissuesin the

BIOLOGICALLABORATORY

PRESS

The Carver Laboratory Press, equipped as illustrated,provides a quick and reliable means for pressing out

samples of vegetable and other oils, juices, extracts,

plant and fruit saps, etc., at required pressures to

20,000 lbs. per sq. in. Standard Hot Plates provide ther-mostatically controlled temperatures to 4000F. CarverCatalog describes press and applications. Mail coupon

for your copy.

Io.FRED S. CARVER INC.HYDRAULIC EQUIPMENT341 HUDSON ST. NEW YORK 14, N. Y.

I Send catalog, describing Carver Laboratory Press and

0- IStandard Accessories. (No salesmen, please.)

RNAM E................................................................................

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

ADDRESS.......................................................................11s

PHOTOVOLT

Radiation-DetectionDensitometer Mod. 500-R

A photoelectric instrument for the exact measure-ment of density of X-ray film employed in personnelmonitoring for protection against harmful radiationin nuclear, radioactive isotope, and X-ray work

Write for Bulletin #270 to

PHOTOVOLT CORP.95 Madison Ave. New York 16, N. Y.

SCIENCE 13November 25, 1949, Vol. 1 10

- ---........................................................................... .1

November 25, 1949, Vol. 110

Personnel PlacementCHARGES and REQUIREMENTS

for "PERSONNEL PLACEMENT" Ads1. Rate: 15¢ per word, minimum charge $3.00 for eachinsertion. If desired, a "Box Number" will be supplied,so that replies can be directed to SCIENCE for immediateforwarding. Such service counts as 8 words (e.g a 25-word ad, plus a "Box Number", equals 33 words\. Allads will be set in regular, uniform style, without display;the first word, only, in bold face type.For display ads, using type larger or of a different

style than the uniform settings, enclosed with separateborder rules, the rate is $15.00 per inch; no extra chargefor "Box Numbers".2. Advance Payment: All Personnel Placement ads, classi-fled or display, must be accompanied by correct remittance,made payable to SCIENCE. Insertion can not be madeuntil payment is received.3. Closing Date: Advertisements must be received bySCIENCE, 1515 Mass. Ave., N.W., Washington 5, D. C.,together with advance remittance, positively not later than14 days Preceding date of publication (Friday of every week).

POSITIONS WANTED

Biochemist: Ph.D., B.S., Ch.E., two years plant chemist in in-dustry; since 1936 research department, university school ofmedicine and teaching hospital; experienced in analysis, toxi-cological work with animals; for fihrther information, please writeBurneice Larson, Medical Bureau, Palmolive Building, Chicago. X

Literature Chemist: Organic, medicinal, Ph.D.? experienced, male,29. University teaching, technical writing, or literature evaluationsBox 377, SCIENMCE. 12/2

Pharmaceutical Chemist: Ph.D., University of California, availableFebruary. Desires academic position or responsible position withpharmaceutical concern. Six months industrial experience. Someteaching experience. Publications. Box 378, SCIENCE. X

Physicist: B.A., Physics, Biology. 72 years experience wide fieldof instrumentation physics applied to medical research including:acceleration, body temp., sound and vibration, radiation, optics.Highly creative. New designs, publications, project responsibility.Want research position. Available now. Box 379, SCIENCE. X

Plant Pathologist: M.S., 25. Research experience. Interestedindustry, academic research. Box 380, SCIENCE. 12/2

Plant Physiologist: Ph.D. Eleven years postdoctoral research-teaching experience fundamental and applied problems, numerouspublications, now with large eastern college, available fall 1950.Box 357, SCIENCE. R 11/25

AVOID DELAY .... Cash in Advance paymentMUST be enclosed with ALL classified ads.(See "Charges and Requirements")

POSITIONS OPENPositions Open:(a) Medical Director: nationally known research organization;radiologist or physicist qualified in administration; exceptional op-portunity. (b) Virologist: preferably Ph.D.; research project in-volving virology, large teaching hospital; laboratory staff of morethan forty; university medical center; Middle West. (c) Bio-chemists: senior research appointments, pharmaceutical company;one should be interested enzyme research, other in general methodsof animal experimentation in endocrinology. (d) Pharmacologist:to direct division of pharmacology research department, largepharmaceutical company; expansion program. (e) Serologist:laboratories, 500-bed general hospital; East. (f) Endocrinologist:to conduct independent research in endocrinology; large pharma-ceutical company; East. (g) Bacteriologist: to head division ofbacteriology, laboratories large voluntary hospital; although M.D.preferred, Ph.D. eligible; will consider recent graduate; $6000-$8000; East. S11-4 Burneice Larson, Medical Bureau, Palm-olive Building, Chicago. X

Te Market Place

BOOKS

OUT-O F-PR I NT and HARD-TO-FIND_w*~~ _ - r ^ ~books supplied. All sub.jects, all languages. Also incomplete sets completed, genealogiesand town histories, all magazine back numbers, etc. Send us yowlist of book-wants-no obligation. We report quickly. LowestDrices.

(We also supply all current'books at bookstoreprices postpaid)

AMERICAN LIBRARY SERVICE117 West 48th St., Dept. 222, New York 19, N. Y.

-P.S. We also buy books and magazines. Send us your list.

Your sets and files of scientific journalsare needed by our library and institutional customers. Please sendus lists and description of Periodical files you are willing to sellat high market prices. J. S. CANNER AND COMPANY, 909Boylston Street, Boston 15, Massachusetts. t0

Send us your Lists of tfSCIENTIFIC BOOKS AND PERIODICALS

which you have for saleComplete libraries; sets and runs; and single titles are wanted

Also please send us your want lists.STECHERT-HAFNER, INC., 31 East 10th Street, New York 3.

WAN1ED TO PURCHASE:SC I ENTI F I C PERIO D I CALS

Sets and runs, foreign and domesticS C I E N T I F I C B OO K SEntire libraries and smaller collections

WALTER 1. JOHNSON125 East 23rd Street, New York 10, N. Y.

For (XIr iitmtw ... give aSCIENCE gift subscription -See page 16

LANGUAGES

LINGUAPHONE MAKES LANGUAGES EASYAt home learn to speak Spanish, Portuguese, Italian, French,German, Russian, by quick easy Linguaphone ConversationalMethod. Save time, work, money. Send for free book. LINGUA-PHONE INSTITUTE, 84 RCA Bldg., New York 20, N. Y.

14 SCIENCE

CHARGES and REQUIREMENTSfor "MARKET PLACE" Ads

1. Rate: 200 per word for classified ads, minimum charge$5.00 for each insertion. Such ads are set in uniform style,without display; the first word, only, in bold face type.For display ads, using type larger or of a different stylethan the uniform clasified settings, and entirely enclosedwith separate rules, rates are as follows:

Single insertion $16.00 per inch7 times in 1 year 14.50 per inch

13 times in 1 year 13.00 per inch26 times in 1 year 11.50 per inch52 times in 1 year 10.00 per inch

2. Payment: For all classified ads, payment in advance isrequired, before insertion can be made. Such advanceremittances should be made payable to SCIENCE, andforwarded with advertising "copy" instructions.For display advertisers, monthl invoices will be sent ona charge account basis-providing satisfactory credit isestablished.S. Closing Date: Classified advertisements must be receivedby SCIENCE, 1515 Massachusetts Avenue, N.W.. Wash-ington 5, D. C., together with advance remittance, positivelynot later than 14 days preceding date of publication (Fridayof every week).For proof service on display ads complete "copy" instruc-tions must reach the publication offices of SCIENCE, 1515Massachusetts Avenue, N.W.. Washington 5, D. C., notlater than 4 weeks preceding date of publication.

Queen's University, Kingston. Canada. Applications are invitedfor the position of Assistant-professor of Theoretical Physics, dutiesto begin September 15, 1950. Recent Ph.D. preferred. Initialsalary $3,750 per annum. Apply to Professor J. K. Robertson,giving full particulars of qualifications and experience, withtestimonials, not later than January 10, 1950. 12/2

November 25, 1949, Vol. 110

The Market PlacePROFESSIONAL SERVICES

GRAPHS, charts, flow sheets drawn for publication. Send yoursketches or data sheets. Accuracy guaranteed. Estimates given.SALLOCH DRAFTING SERVICE, 470 Fourth Avenue, NewYorlk 16, N. Y. R12/9

* MOTION PICTURE and SLIDE FILMPHOTOGRAPHY Professional assistance, editing, sound

recording, art work, animation, titles,complete productions. Microcinema, Time-lapse studies,

I -hotomicrography, optIcal-electr~cal engineering. Research| and Development. 25 years experience, finest references.

HENRY ROGER, Fellow, A.A.A.S.; R.M.S.; B.P.A.;I Formerly 11 years with the Rockefeller Institute.

o ROLAB Photo-Science Laboratories & Sound Studios,.d*L.. SANDY HOOK, CONNECTICUT *-- -

SUPPLIES AND EQUIPMENT

HOLTZMAN RAT CO.Specialzing in the Production of

HIGH QUALITY WHITE RATSfor Laboratory Use.

R. 4, Madison 5, Wisconsin Phone 6-5573

Pure Natural L(+)GLUTAMINEavailable in quantities of 1 Gram upwards.

CHE M OTHERA EUTIC INC360 Glenwood AvenueCHEMO THERAPEUTICS INC.* East Orange, New Jersey

White SWISS Mice 20cRabbits, Cavies, Chickens, Ducks, Pigeons. Hamsters

Write * J. E. STOCKER . Ramsey, N. J.

NEW CHEMICALS FOR MEDICAL RESEARCHPenta and Decamethonium lodides, C.P.

Thiosemicarbazide, C.P.Gold Sodium Succinimide, C.P.lodoacetic Acid and Sodium Salt, C.P.

3106 W. Lake Street Chicago 12, IllinoisNational Biochemical Company

LABORATORY ANIMALS DOGS RATS RABBITSCATS PIGEONS HAMSTERS

Clean healthy well-fed animals MICE POULTRY GUINEA PIGSGuaranteed suitable for your needs. JOHN C. LANDIS . Hagerstown, Nd

Reasonably pried-Dependable serviee

A II Ami no Ac i d s (natural, synthetic, unnatural),Rare Sugars, Biochemical Products, Reagents, New Pharma-ceuticals in stock. Write or phone PLaza 7-8171 for completeprice list.BIO S LABOR.ATORIES, INC 17 West 60th Street,BIOS LAB RATORIES 11 NewYork--23, N. Y.

The Market PlaceSUPPLIES AND EQUIPMENT

TRANSPARENT BOXESFor Every Laboratory, Every Collectorof Small Objects, Every Home Workshop!

Five Sizes Now AvailableWrite for New (June, 1949) Leaflet TR-SR. P. CARGILLE1 8 Liberty Street, New York 6, N. Y.

GLYCOCYAMINE-Hydroxyproline, L-Methionine* AMINO ACIDS * BIOCHEMICALS* PRE-MIXED MICROBIOLOGICAL ASSAY MEDIA

1H. M. CHEMICAL COMPANY, LTD.

144 North Hayworth Avenue Los Angeles 36, California

QUARTZWAREfor laboratory and industry

A complete line of standard laboratory ware.Also custom fabricating to meet your requirements.

Write for particulars.

34THE PANRAY CORP.

340 Canal Street, New York 13, N. Y.

7p4 in ipnuuirieas!

"SCIENCE has been, to date, by far theleading magazine of twelve we are cur-rently using, in terms of inquiries pro-duced.

We'll be ordering more insertions, soon!"(Name on request)

This advertised'started with half-page insertionsin SCIENCE-he's running full-pages, now.

The more than 3&,000 scientists who subscribe toSCIENCE determine just what equipment andsupplies will be purchased for the leading edu-cational institutions, research foundations andindustrial laboratories in the United States and76 foreign countries.

Your advertisement in these columns will bereaching a distinguished, an influential, and a

re.Rponsive audience-at reasonable cost.

SCIENCE 15

FOOD RESEARCH LABORATORIES, INC.Founded 1922

Philip B. Hawk, Ph.D., PresidentBernard L. Oser, Ph.D., Director

IRESEARCH-ANALYSES-CONSULTATIOONBiological, Nutritional, Toxicological Studies

for the Food, Drug and Allied Industries48-14 33rd Street, Long Island City 1, N. Y.

Write for desci-ptive brochure

m

m

m

m

1j_-

1

16November 25, 1949, Vol. 110

A greeting card

will be sent an-nouncing your gift

Weekly subscription will begin with the January6, 1950 issue and expire December 29, 1950.-~MAIL THIS COUPON NOW

TO: SCIENCE Gift Subscriptions1515 Mass. Ave., NW., Wash: 5, D. C.

Enclosed find check in the amount of $7.50 for aSCIENCE Gift Subscription to be sent to:

Name ............

Address ...........

City .. ........ State

Donor's Name .... ..I.....

Address ...........

City .......... State

04.&.S. SYMPOSIA I(7* a 104, double column, illustrated, clothbound)

Twenty of the Symposium Volumes published by theA.A.A.S. have been exhausted. Some unbound copies are

avable, e.g., The Gonococcus and Gonococcal Infection,32 papers, 171 pages, $1.25. The eight titles remaining inprint are shown below with prices: (a) indicates cash pricesto members, (b) prices to nonmembers and institutions.

HUMAN MALARIA, 44 papers on history, parasitology,aaopheline vectors, epidemiology, symptomatology, pathol-ogy and immunity, treatment, control and eradication:repted. 406 pp. (a) $4.00, (b) $5.00.

LIEBIG and AFTER LIEBIG-A Century of Progress isAgricultural Chemistry. 10 papers make available in con-

venient form the history of one of the most significant de-velopments in agricultural science. 119 pp. (a) $2.50.(b) $3.00.

o AEROBIOLOGY, 8 papers on extramural aerobiology containmaterial of interest to botanists, zoologists, agriculturalists,and the general public. 29 papers on intramural aerobiol-ogy deal with air-borne infections. 299 pp. (a) $3.50.(b) $4.00.

RELAPSING FEVER in the AMERICAS, 20 papers on

symptomatology, diagnosis, etiology, epidemiology, pathol-ogy and immunity, tick vectors, treatment, and publichealth aspects. 136 pp. (a) $2.50, (b) $3.00.

DENTAL CARIES and FLUORINE, 11 papers report on

investigations in the British Isles, India, South Africa andthe U.S.A. 111 pp. (a) $3.00, (b) $3.50.

oAPPROACHES to TUMOR CHEMOTHERAPY. 41 papers.

A progress report, addressed largely to future workers. 412pp. (a) $6.50, (b) $7.75.

RICKETTSIAL DISEASES of MAN, 27 papers record thecontrol of Rickettsial diseases during World War II andreveal the scientific foundation on which the adopted meth-ods rest. 255 pp. (a) $5.25, (b) $6.25.

LIMNOLOGICAL ASPECTS of WATER SUPPLY andWASTE DISPOSAL (6 x 9), 8 papers sample the borderarea within the scope of interests common to the engineer,the limnologist, and the oceanographer. 93 pp. (a) $2.75,(b) $3.25.

A.A.A.S. PUBLICATIONS1515 Massachusetts Ave.. N.W.Washington 5, D. C.

Please accept my older for the volumes checked above.

My check in the amount of $.............. is enclosed.

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

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

CITY ..........................................ZONE ... ..... STATE .

GARCEAU ELECTROENCEPHALOGRAPHSUsed In

Argentina . . Brazil . Chilei | " _ . . ~. Guatemala . . . Peru . . .

Cuba . . . Colombia . . . Mexico. . . Canada . . . Ceylon . .. Ice-land . . . Natal . . France . . .

Italy . . . Belgium . . . Czecho-slovakia . . . Hungary . Po-land . . . Trieste . . Portugal

Junior Garceau EEG * * Spain . . . India . . Aus.bimnensions: 18 x 12 x tralia . . . Uruguay . . . U.S.S.R.

9 in. ... New Zealand . . . Orange*in.F~ree State . . . Union of South

Africa . . . Indochina . . . Turkey . . . SwitzerlandMalta . . . Holland . . . Panama . . . Venezuela . . .England . . . and in 40States of the U.S.A.

NO BATTERIESA.C. OPERATED

I NKLESSWRITINGREQUIRE

NO SHIELDINGSHI1PPED

READY TO RUNPROMPTDELIVERY

Eight-channel GarceauEEG Dimensions: 26x 19 x 40 in.

Write for literature.

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

Pioneer manufacturers of the electroencephalograph

16 SCIENCE November 25, 1949, Vol. 110

1111111111L

mp, in RADIOASSAYS

In

ted IDeS;9t --The Auto-

e~IStegrn le Chnger. and

e

scaler,Manua Sampes wh nere l e

TGC type Geiger tubes tere allde-

signed to Operate t hri rifastacurae, and reproducible radio-

assay results.With is

c Om binationigeometrical reproduclbili of

attainable.

Automatic control of StitistiCtlErr The Autoscaler achieves

au-

tomtic counting with a minimum

of

knobairling and data recording.It

counts to a predetermined number

cOunts assure positive controlOf

satistical error. A button is pus

SC, AAutoscaler with PreamP"SC-9 Lead Shielded Manual

TGC. ,e;ger Tube tMicaWinc

TGC-2 Geiger Tube(Mica WinC

tart the instrument and the buialtilctric timer is stopped automatically

when the desired number of counts h

been receied ither amechanical

rer nor interpolat;°n lightsused since all countronically.Roli ble High soltOGpRe9gIatae--The high voltage supplY is variablbetween 500 and 2200 volt adectronically regulated to 0.010/o P

pecent change in line yoltage. High

perte cdrit is less than S volts

absolute.ffier . . . **,..$650.00pIef~anger .. .. ~ $200.00nple Changer m2 ¢* $ 5.0.00jow 3-4 mglcm $f 5.00low less than 2 gcm295) $ 750

Western D),vtzto 2,Cflor'225SnPablo Av,., Berkeley2,Clfrll22955 14", York Office y1.v. 19

moosBldg.. j775 B'WO

General MatdfSM aOtt c tChC9

tO OI.soteWackrll Bldg.. 221 1.LOS0l1.~;cg

This com'pletely new line of miccontinues the tradition of quality est

in 1847 by Charles 4. Spencer,American microscope maker.

cordially invited to see and 1ap

MONOCULARMICROSCOPES

for medical,Industrial, educational

laboratories.for 61bactealabol

11 )

COUNTOPESlustries.

TEXTILE| MICROSCOPES

WATER ANDSEWAGE

MICROSCOPES

LABORATORYMICROSCOPESfor school andcollege use.

fERTIBLESCOPES,.flm9nocularseed work.

PATFMIC

MOLD COMICROSCC

for food proc

BREWMAMICROS(

p