14SINEAVRIEET O.8,N.23

THE STRUCTURAL DETAILS OF THE GIANTSALIVARY GLAND CHROMOSOMES of Drosoph-ila can easily be seen under any compound micro-scope. These chromosomes are unequalled for dem-onstrating the physical basis of mendelian heredity.Permanent microscopic slides of salivary glandchromosomes of Drosophila melanogaster, each $2.25 -With drawing identifying chromosomes and prin- Hcipal "landmarks" in two figures; also slides showing [-- Xtranslocations, X- and Y-chromosomes, etc., each $4.00

Send for free list.AMERICAN GENETIC ASSOCIATION j

Victor Building Washington, D. C.

Objective evidence, a recordthat can be filed and referred to,is invaluable to the physician.With the Garceau Electroencephalo-graph, the following records may beobtained:

ELECTROENCEPHALOGRAMELECTROMYOGRAM

NEUROGRAMELECTROCARDIOGRAMCARDIOTACHIGRAM

STETHOGRAM

A catalogue of our standard models ofthe electroencephalograph will be sent onrequest.

ELECTRO-MEDICAL LABORATORYIncorporated

HOLLISTON, MASSACHUSETTS

USED ElectrocardiografsEinthoven type, suitable for laboratory, experimentalor research work. Table and "portable" models;battery operated, mechanical camera. Complete withall standard accessories, including string and carrier.Priced low ($200 up) to reduce stock. Write for illus-trated price list Si.

SANBORN COMPANY,39 Osborn Street, Cambridge, Mass.

-WE DO TRANSLATIONS-Technical and Scientific Translations

from and into all languagesChemistry, Physics, Biology, Medicine, Metallurgy,Engineering, etc. We do translations of technicalcatalogues, circulars, manuscripts, scientific books.Abstracts, Rewrites of technical articles and patents.

TRANSLATION AND RESEARCH BUREAU55 W. 42nd St., New York, N. Y.

pH of Gastric FluidTest Paper Method of Silverman

and DenisThis simplified test gives information as to theacidity in terms of pH value and also in hydro-chloric acid equivalents. The test is easy tomake and the outfit contains all necessary ma-terials with complete instructions. Price $2.50F.O.B. Baltimore.

LaMotte Chemical Products Co.418 Light St. Baltimore, Md.

i4nOTYPES OFMEYLAN STOPWATCHES

A watch for every purposeAsk for FREE folder No. 10 fully illus-trating and describing some 40 typesof stopwatches. No salesmen will call.

REPAIR [for all kinds of plain and complicated stop.SER,VICE l watches. Send to us for estimates; noSERVICE I.charge, no obligation.

A. R. & J. E. MEYLAN"Specialists in timing instruments"

266 West 40th St, New York City, N. Y.

LARGEST AMEBA Known to ScienceDoctor A. A. Schaeffer, who rediscovered the gigantic

ameba, Chaos chaos, in a New Jersey marsh in 1936, de-scribes it as being the largest and probably one of therarest amebas. In size it is from 50 to 500 times as great(by volume) as the common laboratory ameba and in loco-motion it frequently attains a length to 2 to 5 mm. Nowavailable in pure culture, it offers unsurpassed material tobiology teachers and research students.lV10 Chaos chaos, Type A, Schaeffer strain.

Pure culture containing from 60 to 100 amebas. $3.50Supplied only by

GENERAL BIOLOGICAL SUPPLY HOUSE(Incorporated)

761-763 East Sixty-ninth Place CHICAGO

WANTED

New Products and ProcessesLarge and highly successful company actively engaged in themanufacture and sale of basic drug, pharmaceutical, biologi-cal, medicinal chemical and allied products desires to obtainmanufacturing and sales rights for new products.

Particularly desires products which can be sold in bulk andin large quantities.

Address "MANUFACTURER" care of Science,3941 Grand Central Terminal, New York, N. Y.

II

VOL. 86, No. 223114 SCIENCE-ADVERTISEMENTS

OCTOBER 1, 1937 SCIENCE-ADVERTISEMENTS 15

Before Starting Fall Work INVESTIGATE Laboratory ChowsWHILE MAKING PLANS for the of the country's leading experimentersvvcoming year, investigate Purina now are using these diets. They save

Laboratory Chows- stock and con- much labor, often cost less to feed,trol rations for every sort of experi- are always uniform, promote fecun-mental animal. A very large share dity and good growth.

fefor This Bulletj*This 32-page bulletin givesANALYSES ... INGREDIENTS...FEEDING COSTS ... EXPERI-ENCES of laboratories whichfeed Purina Laboratory Chows.If you haven't a copy we will bepleased to mail one without cost.

PURINA MILLSza 861 Checkerboard Sq.. St. Louis, Mo.

Deteetion of Ferrie IronREAGENT-Resacetophenone

METHOD-Colorimetric ... qualitative

ADVANTAGES-Rapidity... sensitivity .., easeof manipulation

REFERENCES-Cooper, Ind. Eng. Chem., Anal. Ed. 9,354 (1937)

EASTMAN Resacetophenone (No. 4425, 10 g., $1.45) is apurified reagent suitable for such analytical purposes. An abstractof the method employed will be forwarded upon request. EastmanKodak Company, Chemical Sales Division, Rochester, N. Y.

EASTMAN ORGANIC CHEEMICALSp

OCTOBER l, 1937 SCIENCE-ADVERTISEMENTS 15

16 SCIENCE-ADVERTISEMENTS VOL. 86, No. 2231.

ZEISS

SINMPLIFIEDMICRO-PROJECTION APPARATUS

Compact-Light Weight-Brilliant Illumination

T-HE parts of the instrument are housed in a metal case insuch a manner that troublesome adjustments are practi-

cally excluded. A special condenser ensures a correct beamof light. The source of light is an arc lamp, which is so ar-ranged that each carbon can be adjtisted independently. Theposition of the arc may be examined on a ground glass, in thecover of the housing. The carbons are adjusted by two milledknobs which are coaxial and so arranged that they may besimultaneously worked by one hand.

Price with reversing prisms, but without microscope, includ-ing 100 pairs of carbons, for 110 v.D.C.$148.50

for 110 v.A.C... $157.00

A copy of catalog Micro 451/34 will be sent on request

CARL -ZEIS-S, INC.485 Fifth Avenue 728 So, Hill StreetNE.'W Y O R K roA-Lf-%3 LO ANGE LE S

E~~~~NA~~ ~

16 SCIENCE-ADVERTISEMENTS, VbL. 86, No. 2231