SCIENCEt k.

NEwSERi2s FRIDAYSDPCEMBER22O 1939 SuNBsCOPIo, $6.00VOL. 90, No. 2347FIA,DCME 2,199SINGLEM COPIES, .15

EIMER & AMENDPHOTOELECTRIC COLORIMETER

For Comparing and MeasuringTotal Light Transmission and

Turbidity of Liquids

ApplicationsThe Eimer and Amend Photoelectric Colorimeter can be used wherever "visual"

colorimetric methods are employed.Published determinations with this type of instrument include the following: Fluo-

rides, HCN (turbidity), Blood sugar, Urine sugar, Blood creatinine, Cholesterol, Hemo-globin, Indican, Bilirubin, Nitrogen, Blood protein, Urine protein, Spinal fluid protein,Urea, Creatine, Guanidine, Amino acids, etc.

In addition to quantitative chemical analysis, the photoelectric colorimeter has beenemployed in the following investigations:

Gelatinization, Hydrogen ion concentration, Reaction Kinetics, Starch-iodinesystem, Turbidity, Luminosity of bacteria, Population Density of microorgan-isms, Strength of dyes, Opacity and brightness, Iron, Chromium, etc.

BULLETIN P-546Completely DescribesInstrument and Cites

100 Literature ReferencesSent Upon Request

EIMER & AMEND:e. .* .3.

205-223 THIRD AVENUE, NEWYORK

Entered as 8econd-cla88 matter July 18, 1923, at the Post Office at Lancaster, Pa., U. S. A., under the Act of March 3, 1879.

2 SCEC-DETSMNT O.9,N.24

At the A.A.A.S. Conventiondo not fail to visit

Booth 100See

BIOLOGICAL ABSTRACTSNew sectional publications.

Since January 1939 we have been pub-lishing FIVE SEPARATE SECTIONS aswell as the complete edition. One or moreof these sections will be a valuable asset inyour reference library. It saves time andis the only practical way to keep up withthe biological literature.

See a sample copy and subscribe!or write for information toBIOLOGICAL ABSTRACTSUniversity of Pennsylvania, Phila., Pa.

QUALITATIVE ANALYSIS and CHEMICAL EQUILIBRIUMTHORFIN R. HoGmNsS AND WARREN C. JOHNSON

University of ChicagoAdopted in 62 institutions this year

"The introduction of modern atomic concep- "The book appeals to me as being mueh thetions is most excellent, as well as the problems best effort so far to reduce amounts of materialand simple mathematical calculations." J. E. in elementary inorganic qualitative analysis,

Zanetti Cuwithout getting into the more specialized microZanetti, Coh'znmba University. methods." R. D. Cool, University of Akron.

$2.75

ELECTRICITY ANDMAGNETISM

S. IEOY BROWN University of Texas"I was favorably impressed by a great manyfeatures. The treatment of alternating currentsand alternating current circuits is handled veryskilfully. The large number and wide varietyof problems is a very excellent feature." B. H.Dickinson, University of Maryland.

Price, $2.80

257 Fourth Aver

A COLLEGE COURSEIN SOUND WAVES AND ACOUSTICSM. Y. COIBY University of TexasDesigned to give students a thorough groundingin the fundamental principles of wave motion,objective sound, and acoustics. The course, asoutlined, is the outgrowth of classroom practice,and has been developed during fifteen years ofteaching experience.

Price, $2.80

Hugh Miller's

History and ScienceA Study of the Relation of Historical

and Theoretical Knowledge

An important contribution to currentphilosophical controversy. The auth-or's theme is that theory and historyare everywhere two complementary ap-proaches to natural knowledge and thateach is equally of general application.

Price, cloth, $2.00

Order through your bookseller,or direct from

THEUNIVERSITY OF CALIFORNIA PRESS

BERKELEY:: CALIFORNIA

HENRY HOLT AND COMPANYmue New York, New York

SCIENCE-ADVEBTISEMENTS VOL. 90, NO. 23472

wo4d4f Voa.z a&ewtm

DEEBR2,13 CEN EA V RIE E T

PREVIEW OF THE ANNUAL EXHIBITIONof the American Association for the Advancement of Science, The Civic Auditorium,

Columbus, Ohio, December 27 to December 30

The exhibition of the American Association for the Advancement of Science will this year beheld at the Civic Auditorium, Columbus, Ohio, from December 27 to 30.We wish.. to express our appreciation for the cooperation that we have received from the exhib-itors who have helped to maintain the high standards of the exhibition. Some institutions andconcerns who have recently decided to take part in the exhibition have not had time to senddescriptive material for publication in this issue of Science. A brief description of exhibitsfollows. OWEN CATTELL,

Director of Exhibits

BAKELITE CORPORATIONNew York

Booth No. 59Of particular interest are working demonstrations on

laboratory testing machines. These demonstrations revealhow Bakelite engineering laboratories test plastic mate-rials for such properties as impact resistance, stiffnessand power factor. In addition, are a stretchability dem-onstration of the new "Vinylite" polyvinyl acetal resinfiller for safety glass, and a stress and strain analysis ofBakelite transparent cast resinoid models under polarizedlight. Supplementing these action features are forty casehistories illustrating how Bakelite materials have aided inthe solution of engineering problems, particularly by theirresistance to chemicals and corrosion.

BATTELLE MEMORIAL INSTITUTEColumbus

Booth Nos. 7, 8The Institute will display photographs of scientific and

industrial research in progress in its laboratories. Amember of the technical staff will be in attendance tofurnish information about Battelle, and to be of assis-tance to visitors.

BAUSCH AND LOMB OPTICAL COMPANYRochester, N. Y.Booth Nos. 75, 84

A most complete display of optical apparatus includinglaboratory, research and wide field microscopes, miero-tomes, microscope accessories, microprojectors, Balopti-cons, photomicrographic equipment and optical measuringinstruments will be set up for operation. Available newitems will be shown. New features have also been in-corporated on our established line of instruments. Ourmany friends are invited to pay us a visit. Messrs. J. H.Schering, H. L. Shippy and G. H. Leffler will greetvisitors.

BIOLOGICAL ABSTRACTSUniversity of Pennsylvania

Booth No. 100The only English language abstracting and indexing

service which covers the entire field of biological litera-ture. The abstracts are from more than 1,100 biological

journals published in 18 languages throughout the world.This "Service to Science" enables the research workerto keep up with the ever-mounting current biological lit-erature. Featured at the display will be the new sectionalplan inaugurated in 1939. Dr. John E. Flynn, Editor-in-chief, Miss R. J. Feldman, Librarian, and Mr. Pierce W.Anthony, Business Manager, will be in attendance to ex-plain the new section plan and point out the time-savingusefulness of Biological Abstracts.

THE BLAKISTON COMPANYPhiladelphiaBooth No. 88

The Blakiston Company will this year present at theColumbus Meeting an interesting exhibit not only of theirnew texts and references but their complete line in thevarious fields of science. New texts in ComparativeAnatomy, Organic Chemistry and Inorganic Chemistrywill be featured. Messrs. J. Brooks Stewart and E. R.Stetson will be in attendance, and Mr. Robert F. Bowmanwill be present one or two days.

BOYCE THOMPSON INSTITUTE FORPLANT RESEARCH, INC.

Yonkers, N. Y.Booth No. 98

Photomicrographs and x-ray diffraction patterns will beused to illustrate the formation of cellulose particleswithin the chloroplasts of Halicystis and within the color-less, plastid-like structures in the Cotton Fiber. The for-mation and structure of the cell membranes of these twocells from cellulose particles and other substances of proto-plasmic origin will be demonstrated in a similar fashionalong with samples of various membrane constituentsDr. Wanda K. Farr will be in attendance.

CARNEGIE INSTITUTION OF WASHINGTONDepartment of Genetics

Cold Spring Harbor, N. Y.Booth Nos. 81, 82

Exhibit of results of induced polyploidy in floweringplants, by A. F. Blakeslee, A. G. Avery, A. D. Bergner,S. Satina, H. E. Warmke and E. W. Sinnott. Colchicineinduces elimination of chromosomes as weli as doublingtotal number. It may affect the three primary layers

DECEmBFa 22, 1939 SCIENCE-ADVERTISEMENTS 3

4 SCIENCE-ADVERTISEMENTS

differently producing chimeras in which one can determinewhat each germ layer contributes by differences in chro-mosome number. Characteristics of polyploids and effectof polyploidy on sex mechanism in Melandrium are illus-trated. Three ways are shown in which "new species"Imay be made by laboratory methods. The first methodis not yet known in nature; the second is suspected innature; the third is known to have oecurred in the originof elite varieties of cultivated plants and many speciesin nature.

FRED S. CARVERNew York

Booth No. 60The Carver Laboratory Press, now in use throughout

the world in research and development work of manykinds, will be shown. This is standard apparatus whichhas been used particularly on most of the recent develop-ments in plastics; it is also used for biological studies,pressing of plant and animal tissue and separation ofliquids from solids; metallographic and various otherapplications-in the colleges, government departmentsand commercial institutions. The Press will be shownwith its various accessories and methods of applicationfor these different uses.

CENTRAL SCIENTIFIC COMPANYChicago

Booth Nos. 52, 53The exhibit of the Central Scientific Company will again

feature some of the new developments in the laboratoryand research field and as many as possible of the displayitems will be in operation. Some of the interesting newdevelopments include a spectrophotometer, which will beknown as the "spectrophotelometer," to be made avail-able at a price within reach of the average budget; sev-eral new light sources; a new low-priced hydraulic presswith accessories for demonstrations and experiments on

pressure transmission by liquids as well as the verificationof Hooke's law; a horn gap spark discharge apparatus;and a number of new developments in demonstration lec-ture equipment.

CHICAGO APPARATUS COMPANYChicago

Booth No. 101The exhibit of the Chicago Apparatus Company in-

cludes among many other modern items for Physics,Chemistry and Biology a new fool-proof Tesla Coil forhigh-potential, high-frequency demonstration work; newnon-breakable Durolatex Anatomical Models of rubber;Visiograph Filmrols for preview and review work inphysics, etc. Representatives in attendance: Dr. EdgarBaird, Nelson Worick and M. C. Stoelting.

CLAY-ADAMS COMPANYNew York

Booth No. 13Clay-Adams will exhibit a number of new botanical

and zoological models, and will also have available the

"Durable" Anatomical Models of pressed paper, of in-terest to anatomists, physiologists and psychologists.Examination of this material will show readily the fea-tures which make some of these models outstanding fortheir relative completeness and lasting qualities.

THE COLEMAN AND BELL COMPANYNorwood, OhioBooth No. 45

This exhibit will consist of Coleman and Bell Labora-tory Reagents, including Inorganic and Organic Chem-icals, Biological Stains, Chemical Indicators and Diag-nostic Solutions. In certain instances, steps in the manu-facture of certain items will be shown, including the rawmaterials and apparatus involved.

COMMERCIAL SOLVENTS CORPORATIONTerre Haute

Booth Nos. 1, 112The production of the nitroparaffins and their deriva-

tives, as shown in this exhibit, makes available to thechemical and process industries an entirely new group oforganic chemicals which give every promise of attainingmajor industrial importance. The nature and propertiesof the nitroparaffins, and of the numerous compoundswhich can be synthesized from them, are so varied thatpractically every branch of industry will find these newchemicals of value in improving present products or proc-esses and in developing new products. One of the mostinteresting characteristics of the nitroparaffins is theirgreat versatility in chemical syntheses. They not onlymake possible the preparation of a very large number ofnew chemicals, but the reactions involved can in mostcases be controlled to give the product desired in highyield. Mr. Walter Scheer and Dr. F. C. Dolian, of theMarket Development Division, will be in eharge.

DENOYER-GEPPERT COMPANYChicago

Booth No. 64New accurate models made in our Chicago Studios

await examination. On display will be models of thelarynx, urinary apparatus, brain, skin, eye, ear, heart,and torso with head. Durably constructed of "FibrineComposition," these visual aids will serve for years andwill greatly increase the effectiveness of teaching efforts.

DUQUESNE UNIVERSITY BIOLOGICALLABORATORIES

PittsburghBooth No. 89

Dr. R. T. Hance will present the making of histologicalpreparations showing speedier fixation; new dehydrationmethods; imbedding mixtures that may be varied in theirapplication; and increased rapidity of staining. An ex-hibit prepared by Ralph Chermock will show the distri-bution of the relatives of Papilio machaon in NorthAmerica, with their interrelationships being illustrated bytheir distribution and the environmental effects involved

SCIENCE-ADVERTISEMENTS VOL. 90, NO. 23474

DECEMBER 22, 1939 SCIENCE-ADVERTISEMENTS

in their coloration. Demonstrations of the facility withwhich microscopic slides of insect genitalia may be pre-pared involving cleaning, staining, the use of "Cello-solve " in dehydration, and mounting. The original chartsused in teaching zoology to the blind will be shown.

EASTMAN KODAK COMPANYRochester, N. Y.Booth No. 44

The exhibit of the Eastman Kodak Company featuresthe new, versatile Kodak Precision Enlarger. This ma-chine provides a comprehensive series of highly advancedequipment. In addition to a series of matched lenses andcondensers, aceessories are shown which readily adapt theEnlarger for use as a camera. In this connection it maybe used for out-of-the-ordinary jobs such as copying andtitling, and photomacrography and photomicrography oflaboratory specimens. Another accessory makes it easy touse the Enlarger as an independent camera. Other newequipment such as an enlarger for miniature slides isshown also. Mr. Wm. S. Allen and Mr. H. J. Christy willbe in attendance.

FORD MOTOR COMPANYDearborn, Michigan

Booth No. 42The Johansson Gage Block exhibit will consist of

various sets of Johansson Gage Blocks and Accessories.Several demonstrations of how these accurate gaging toolsmay be used will be on display as well as a series of 70slides in an Automatic Balopticon. Chrome-plated Jo-hansson Gage Blocks will be exhibited for the first time.The exhibit will be in charge of Mr. 0. E. Green, assistedby Mr. 0. L. Kelley.

GRADWOHL LABORATORIESSt. Louis

Booth No. 6This organization will demonstrate new and accepted

methods of blood typing and blood grouping. The workwill show the up-to-date and complete methods for bloodtyping in connection with blood transfusion. Specialattention will be given to the subgroups of A, namely,A1 and A2. In addition to this, the genetics of M and Ngroups will be related and demonstrated. The M and Ngroups are of great importance in determination of pater-nity. Parasitological demonstrations will also be madein this exhibit. Mr. and Mrs. Lucian Erskine will be inattendance.

GRAF-APSCO COMPANYChicago

Booth No. 78As the originators of rebuilt microscopes in America,

the Graf-Apsco Company features an exhibit of rebuiltequipment, together with their new instruments. It isinteresting to note the contrast of old microscopes beforeand after rebuilding. Other items being exhibited are:Stereografs, dissecting instruments, magnifiers, etc., aswell as a complete line of mechanical drawing instruments.Mr. J. M. Graf is in charge of the exhibit.

5

GUTHRIE CLINICRobert Packer Hospital

Sayre, Pa.

Booth Nos. 24, 25This exhibit demonstrates the preoperative preparation

for and the use of silk in the surgical treatment of hyper-thyroidism. Displayed on cold front, especially builtilluminators, using fluorescent lighting, negatives ofpatients before and after operation, eight photomicro-graphs of thyroid pathology, fifteen line drawings demon-strating the technique of thyroidectomy made by Diduschand reproduced on translite. A color, sound movie willbe demonstrated, utilizing lateral projection on a silversurfaced mirror with the beam reflected on a translucentscreen. The movie will display the actual operative pro-cedure of thyroidectomy using silk sutures. Dr. S. PaulPerry and Dr. F. Harriman Jones, members of the staff,will be in attendance.

INSTITUTUM DIVI THOMAE

CincinnatiBooth Nos. 72, 73

There will be shown effects of respiratory-stimulatingfactors from cells in changing the abnormal metabolismof tumor tissues so that it resembles that of normal tis-sues, by stimulating their respiration and depressing theiraerobic and anaerobic glycolysis. The relation of thismechanism to natural and induced immunity to tumorsin animals will be illustrated. Examples of the produc-tion of tumors by factors from injured cells will beexhibited. In the field of plant physiology, the rhythmicrate of growth of seedlings will be shown with the aidof the optical lever, and pollen tube culture will be demon-strated.

PROFESSOR CHAS. T. KNIPPUniversity of Illinois

UrbanaBooth No. 9

The exhibit will consist of two parts: (a) Cold CathodeRectifier. This will be exhibited in improved form.Advantage is taken of the rectifying action when theCrookes dark space is limited by the physical dimensionsof the discharge tube. The tube exhibited will rectify25,000 volts A.C. By a proper placement of individualunits the total rectification may be greatly inereased.The operation of a single unit will be on display. (b)Molecular Bombardment. This is shown by two separatetubes operated simultaneously. The demonstration of afew years ago has been augmented by a companion tubeshowing the bombardment of mercury molecules on a diskof balsa wood placed within the tube. Conclusions re-garding interatomic action may be drawn by studying andcomparing the phenomena within the two tubes.

6 CEC-DETSMNT O.9,N.24

LEEDS AND NORTHRUP COMPANYPhiladelphiaBooth No. 29

Our display will include one new instrument and one

newly redesigned. Speedomax, the high-speed recorder,has been redesigned to simplify, improve and standardizeits construction. To demonstrate the fast response ofthis instrument, it records the emf of a Rayotube (radia-tion pyrometer) sighted on an intermittent target. AnL&N Optical Pyrometer will be shown which is entirelynew. Measuring by a combination of the optical-balanceand potentiometric methods, it reads in degrees, and isdesigned to give fast, convenient and accurate tempera-ture measurements. On display also is the Mueller Bridgefor extremely high-precision temperature measurementsby the electrical resistance-thermometer method and theportable Universal pH Indicator. Representatives in at-tendance will be Mr. C. E. Applegate, Philadelphia Office;Mr. J. F. Sneath, Cleveland Office.

BIOLOGY DEPARTMENTSaint Louis University, St. Louis

(Professor B. J. Luyet)Booth No. 86

An exhibit illustrating the States of Matter and Proto-plasm at Low Temperatures: The vitrification gun, an

apparatus for producing solid amorphous water by ex-

tremely rapid cooling; photographs of vitrified and devit-rifled water seen under the polarizing microscope; phasediagrams of the vitreous-crystalline states of water andof some carbohydrate solutions; the nature of the vitreousstate, specimens of vitreous and partially devitrified mat-ter; plants grown from seeds exposed to -1950 C. belowzero; entire plants which had survived exposure to thistemperature; action of freezing temperatures on animals(fishes and lower forms).

McGRAW-HILL BOOK COMPANYNew York

Booth No. 58Advance proofs of important forthcoming books in

the field of science will be on display at the McGraw-Hillbooth. You are invited to see at this booth also an exhibitof recent MeGraw-Hill books in the fields of Agriculture,Astronomy, Biology, Chemistry, Education, Forestry,Geography, Geology, Mathematics, Metallurgy, Physiesand Psychology.

THE MACMILLAN COMPANYNew York

Booth Nos. 56, 57The book exhibit sponsored by The Macmillan Com-

pany contains approximately eight hundred and fiftyvolumes-undergraduate and graduate text-books, refer-ence books, and technical and scientific books designedfor the general reader. The following classifications are

represented: Agriculture, the Biological Sciences, Chem-

istry, Engineering, History of Science, Home Economies,Mathematics, Medical Science and Physics. The follow-ing representatives of The Macmillan Company will be inattendance at the booths: Mr. Ranald P. Hobbs, Mr.Charles L. Skelley, Mr. Dwight Hoover, Mr. Donald M.Nelson, Mr. John S. Crossman and Mr. Arthur Evans.

MERCK AND CO., INC.Rahway, N. J.

Booth Nos. 62, 63The display is devoted entirely to the theme of syn-

thetic vitamins, in which the company is particularlyinterested. A central panel, headed by an illuminatedrepresentation of crystalline vitamin B1 carries a ropemodel diagram which traces the origins and inter-rela-tionships of the various members of the vitamin B com-plex. Brief descriptions are given of riboflavin, nicotinicacid, pantothenic acid, vitamin B. and vitamin B1, and atranslucent colored chart shows the complete synthesis ofthe latter vitamin according to the procedure of Williamsand his coworkers. Large molecular models of the struc-ture of the vitamins C, K, B, and E are displayed. Thesyntheses of vitamin K and of vitamin B. as determinedin the Merck Research Laboratories are shown in detail,in the two main panels. Descriptive detail and informa-tion are given concerning vitamins C and E. Dr. C. R.Addinall will be in charge of the exhibit.

THE NATIONAL GEOGRAPHIC SOCIETYWashington, D. C.Booth Nos. 30, 31

The exhibit of the National Geographic Society willfeature a full-size facsimile of the ancient Mexican stonemonument on which the oldest recorded date yet discov-ered in the Western Hemisphere is carved in Maya sym-bols. The date is equivalent to November 4, 291 B.C., andthe stone on which it is recorded was uncovered by a jointexpedition of the National Geographic Society and Smith-sonian Institution. The monument is considered to beone of the most important archeological finds in theAmericas. The exhibit will include photographs of otherobjects found by the expedition and of its work in thefield. Mr. E. John Long and Mr. F. Barrows Colton ofthe staff will be in attendance.

THE OHIO STATE UNIVERSITY ANDCOOPERATING INSTITUTIONS

Industrial Research FoundationBooth No. 27

The Ohio State University Research Foundation willdisplay photographs, charts and literature illustrating itswork in bridging the gap between academic research andthe applications of research in industry. Emphasis willbe placed on the educational value of bringing scientificproblems arising in industry to the attention of universityscientists and of acquainting industrial executives withthe contributions that can be made to industry by scien-tifically trained investigators. Dr. A. R. Olpin and Mr.J. M. Weed will be in charge.

VOL. 90, No. 23476 SCIENCE-ADVERTISEMENTS

DECEMBER 22 1939 SCIENCE-ADVERTISEMENTS 7

BIOCHEMICALSOF NUTRITIONAL INTEREST

Carotene and various carotenoid pigments, in crystallineform, oil solution and aqueous colloidal suspension.

Thiamin Chloride

Riboflavin-natural and synthetic, in crystalline formand in concentrates.

Nicotinic Acid, Nicotinic Acid Amide and biologicallyimportant derivatives.Ascorbic Acid2-methyl-1,4-naphthoquinone2-methyl-1,4-naphthohydroquinone diacetate(Two compounds above exhibit vitamin K properties)

Pimelic AcidBeta AlanineGlutamine

Amino acids, including monosodium d-glutamate,d-glutamic acid and hydrochloride, I-leucine, /-tyrosine,3,5-diiodotyrosine, tyramine hydrochloride and argininehydrochloride.Galactose, phytin, vitamin-free casein and other dietmaterials for biological assay.

The biochemicals listed above are prepared especially for research andexperimental use by scientific investigators, offered in bulk quantities.Further information and prices will be supplied upon request.

GENERAL BIOCHEMICALS, INC.418J REPUBLIC BUILDING, CLEVELAND, OHIO

I11-I

DECEMBEP. 22, 1939 SCIENCE-ADVERTISEMENTS 7

SCIENCE-ADVERTISEMENTS VOL. 90, No. 2347

Depts. of Physics and Electrical EngineeringBooth Nos. 18, 19, 20, 76, 77

The Department of Physics of Ohio State Universitywill exhibit equipment used in nuclear research. Diffrac-tion of light by supersonic standing waves in a liquidwill be demonstrated. The Department of Electrical En-gineering will show acoustical models of radio antennasystems, which have been used with marked success in pre-

dicting the radiation patterns of radio antenna. Soundsources and pick-up devices developed for this work may

find application in purely acoustical problems. Thetransmission of electromagnetic waves down pipes may

be described as single-conductor transmission of power.

The apparatus on exhibit is being used in studying more

efficient methods of transferring power from the source

to the guide, and of converting the transmitted energy

into available form at the far end. Mr. Edward Jordanand Mr. Sloan Robertson will be in attendance.

Astronomy on the Pacific CoastBooth No. 34

The center of attraction will be a large celluloid modelof the giant 200-inch telescope now being erected on

Mount Palomar in California. The model was constructedat a cost of $2,000, and it shows all the intricate featuresof the great telescope. Drawings by Russell Porter willillustrate the telescope in its natural setting. A photo-graphic map of the Milky Way, from the Mount WilsonObservatory, shows the location of Cepheid Variable Stars.Other exhibits from Mount Wilson are photographs ofcelestial objects taken through filters of various colors.The Liek Observatory has contributed photographs show-ing the moon at various phases, enlarged sections of themoon, the Pleiades, several prominent nebulae and Direc-tor Wright's famous photographs of Mars and San Josein violet and infra-red light.

Astronomy in OhioBooth No. 35

Here may be seen a model of the proposed new observa-tory for Case School of Applied Science. The large tele-scope will be of the new Schmidt photographic type. Pho-tographs of the little observatory on the campus ofWestern Reserve Academy, at Hudson, and its founder,Elias Loomis, will be featured. This small observatory is101 years old, and it was the first astronomical institutionto be erected west of the Allegheny Mountains. Photo-graphs of numerous Ohio observatories will be shown.Pictures of the Perkins Reflector, now fifth largest tele-scope in the world in operation, its new spectrograph andspectra recently obtained may be seen.

Astronomy in the Eastern United StatesBooth No. 36

Interesting astronomical information will be illustratedby several models. Transparencies illustrating the work

of the Michigan Observatory and the U. S. Naval Obser-vatory will be on display. The Michigan Solar Observa-tory and its South African telescope will be illustrated.Contact prints from the star-chart plates of the CookObservatory may be seen. Samples of the research workcarried on at- the Sproul, Allegheny, Dearborn, Yerkesand Harvard Observatories will be featured. The Har-

vard exhibit should be of particular interest to astrono-mers, since it contains recent photographs of objects inthe southern heavens, not generally accessible to telescopesin the United States. Recent motion pictures of solardisturbances, from Michigan, will be shown in the pro-

jection room.

Plant Pathology

Booth Nos. 65, 66

Dr. Wolf, who last year supplied the interesting exhibiton blue mold, will again bring an exhibit to the Columbusmeeting. Dr. Stakman will exhibit mutations and sexualrelationship of fungi. Large paintings produced by an

artist will make the exhibit outstanding. Helminth-sporium and Stewart 's disease on Dent Corn Hybrids willbe the subjects of an exhibit by C. W. Ellett.

Phonetics and Chemical Abstracts

Booth No. 28

An exhibit on experimental phonetics dealing withpalatography (tongue-palate contact). Pseudo palateswith false windows connected by small tubing to tambourand kymograph are used to show how rate of articulationis related to area of palatal contact. These contacts are

photographed, enlarged and measured with a planimeter.Dr. E. R. Moses, Jr., will be in attendance. The editorialoffice of Chemical Abstracts, which is located on the cam-

pus of Ohio State University, will be represented by a

display illustrating the preparation of abstracts andindexes.

Engineering Experiment Station

Booth No. 99

The problem of three-dimensional photo-elastic stressanalysis has been nicely solved by Royal Weller in theEngineering Experiment Station of The Ohio State Uni-versity. It consists essentially of slicing a strained solidmodel by means of a thin light beam or band. Thelight band is applied at right angles to the line of sightand moved parallel to it. The fringe pattern producedis only that of the part of the model illuminated. Asomewhat different mathematical procedure from the ordi-nary has been developed by him for quantitatively analyz-ing this fringe pattern. He has also developed an iterativeprocedure for analysis. The experimental apparatus forthis method will be set up and operated. Mr. H. J.Hoffman will be in charge.

8

DECEMBER 22, 1939 SCIENCE-ADVERTISEMENTS 9

*..W/C tilie

pencerLI

r Spencer"To design an objective lens

for a microscope is a monumen-tal task. It requires months ofwork with sine tables and com-puting machines.

No less a task is the actualproduction of the lens elementsand mechanical parts that make

up the completed objective. Itcalls for almost incredible skill-skill that can cope with tol-erances of millionths of an inch.

The average man little com-

prehends this. But the scientistdoes-and it is this fact whichgives such impressive signifi-cance to the almost universal

acceptance of Spencer Micro-scopes in scientific circles, and

gvsadded meaning to' the;k words "Spencer precision" and

"Spencer quality."

ens CompanyMICROSCOPES REFRACTOMETERSMICROTOMES - COLORIMETERSPHOTOMICROGRAPHIC |U|iFFrALO SPECTROMETERSEQUIPMENT PROJECTORS

SPENCER INSTRUMENTS WILL BE DEMONSTRATED IN BOOTHS 38-39,AT THE ANNUAL MEETING OF THE AMERICAN ASSOCIATIONFOR THE ADVANCEMENT OF SCIENCE, COLUMBUS, OHIO

DECEMBER 27-30.

SI

DECEMBER 22, 1939 SCIENCE-ADVERTISEMENTS 9

10 SCIENCE-ADVERTISEMENTS

PRENTICE-HALL, INC.New York

Booth No. 43

Important new scientifie publications are again featuredin the book exhibit presented by Prentice-Hall. The dis-play includes undergraduate and graduate texts in Phys-ics, Chemistry, Mathematics and Engineering, as well asin Psychology, Geography and the Social Sciences. Ofoutstanding interest are Herzberg's "Molecular Spectraand Molecular Structure," Albright's "Physical Meteor-ology, " Rollefson and Burton 's " Photochemistry, " Mid-dleton and Willard 's "Semimicro Qualitative Analysis,"Taylor 's " Vector Analysis " and " Applied GeneralStatistics" by Croxton and Cowden, all recent publica-tions. Also featured are Haskins' "Of Ants and Men"and Strong 's " Procedures in Experimental Physics."Mr. Warrington and Mr. Daley will be in charge.

W. B. SAUNDERS COMPANYPhiladelphiaBooth No. 46

The exhibit will include their complete line of text-books and reference volumes dealing with the medical andbiologic sciences. Of special interest will be the newtext-book of "Clinical Biochemistry" by Cantarow andTrumper; also, Bliss, "Introductory Guide to Biochem-istry," Sturtevant and Beadle, "Introduction to Genet-ies," McNally, " Medical Jurisprudence and Toxicology, "King and Roser, "Anatomy and Physiology LaboratoryManual." There will be new, revised editions of severalstandard works such as Todd and Sanford, ''ClinicalDiagnosis by Laboratory Methods," Marshall, "HumanAnatomy, " Schneider, " Physiology of Muscular Activ-ity,' Bogert, " Nutrition and Physical Fitness, " Me-Lester, " Diet and Nutrition in Health and Disease, "Wolf, "Endocrinology. " Representatives in charge ofthe display are Messrs. E. R. Zieber and John A. Behnke.

THE SCIENCE PRESS PRINTING COMPANYLancaster, Pa.Booth No. 55

Publications printed by The Seience Press PrintingCompany will be exhibited. Books and journals can beexamined and orders placed. Blanks for inclusion ofbiographies in "American Men of Science" and "Lead-ers in Education" can be filled out. Information andsuggestions will be given concerning the methods andcosts of scientific printing. Mr. Jaques Cattell will bein charge.

SOCIETY FOR RESEARCH ON METEORITESThe Ohio State University

ColumbusBooth No. 23

The exhibit of the Society for Research on Meteoriteswill feature a working model of a meteorite detector

and a collection of meteorites recently discovered byinstrumental search; a Missing Meteorite Bureau; modelsof meteorite craters; collections of tektites, meteoritic ironartifacts and pseudo-meteorites; specimens of rock meta-morphosed by meteoritic impact; collections of trans-parencies, photographs and literature relating to meteoritecraters, the great Siberian meteorite fall, the recentlydiscovered Tilden, Paragould and Goose Lake Meteoritesand modern work in meteoritics in the United States; areticle used in plotting the apparent paths of meteorsand many other items relating to meteoric astronomy.

SPENCER LENS COMPANYBuffalo

Booth Nos. 38, 39

Visitors who come to the display of Spencer Lens Com-pany will have ample opportunity to inspect and havedemonstrated to them Spencer instruments that combinelatest developments. Of particular interest will be thenew low power binocular microseopes and the new SpencerPathologist 's microscope. Research and Laboratorymicroscopes, microtomes, photomicrographic equipment,Delineaseopes and many other seientific instruments willbe arranged so that visitors can easily see them in opera-tion. Mr. J. P. Baker, Mr. J. J. Host and Mr. A. H.Fleck will be in attendance to discuss any optical questionsvisitors have in mind.

UNIVERSITY PRESSESA Cooperative Exhibit

Booth No. 33Fourteen university presses will display recent publi-

cations reporting and interpreting original research andscholarship, text-books exemplifying new methods, andproceedings and reports of learned societies. Miss DorisForce, of the University of Chicago Press, will be incharge of the exhibit in which the following presses willparticipate: California, Chicago, Collegiate (Iowa StateCollege), Columbia, Cornell, Duke, Harvard, Minnesota,North Carolina, Oklahoma, Oxford, Princeton, Stanfordand Yale.

U. S. BUREAU OF PLANT INDUSTRY, WASH-INGTON, D. C., IN COOPERATION WITHTHE BIOLOGICAL INSTITUTE OF

SAO PAULOBooth No. 83

Exhibits: (1) Myriangiales, especially those of thegenus Elsinoe, as they attack economic plants or theirrelatives in the United States, Puerto Rico and Guam,together with photographs and color drawings, the speci-mens representative of " Myriangiales Selecti Exsiccati,"Fase. II, in preparation; (2) Parallel agar media culturesof Myriangium and Elsinoe species for comparison of char-acteristics. Dr. Anna E. Jenkins will be in attendance.

10 SCIENCE-ADVERTISEMENTS VOL. 90, NO. 2347

DEEBR2,13 E C-A ETI M NT 11

U. S. DEPARTMENT OF THE INTERIORGeological Survey

WashingtonBooth Nos. 2, 3, 4, 5

The exhibit shows recent activities of the Division ofGround Water of the Geological Survey, United StatesDepartment of the Interior. It includes: (a) graphsshowing several different types of fluctuations of waterlevels in wells, including unusual fluctuations caused bytrains, earthquakes, ocean tides, earth tides and changesin barometric pressure; (b) graphs showing long timerecords of fluctuations of wells in several widely scatteredparts of the United States, some of them going back to1892; (c) photographs showing equipment used to exploredeep wells for leaks and contamination by salt water, withgraphs showing results of such exploration; (d) graphsof fluctuations of ground-water level obtained during acurrent investigation in the vicinity of Cincinnati.

VASSAR COLLEGEDepartment of Botany

Booth No. 15The structure of some chloroplasts will be demonstrated

by means of photomicrographs. These will show a sur-face view of chloroplasts not containing starch, showingplastidules and some containing starch also showingplastidules. There will be median optical views of theabove. Kodachrome slides of chloroplasts will be showndaily. There will also be models. The above will showthe plastidule units of which the chloroplast is composedand the plastid granules of which the plastidule is made.The chlorophyll will be shown to be present in the colloidalsubstance of the plastid granule and the starch unit, whenpresent, will be seen in the center of each plastid granule.

VIRGINIA AGRICULTURAL EXPERIMENTSTATION, COOPERATING WITH DUKE

UNIVERSITY, AND THE NORTHCAROLINA DEPT. OF

AGRICULTUREBooth No. 70

Investigating new methods for the control of plant dis-ease. Quantitative methods basic to toxicological inves-tigations of the effect of organic vapors on plants areillustrated. Living tobacco seedlings infected with a dis-ease-producing agent, Peronospora tabacina, are subjectedto known vapor concentrations of paradichlorobenzene.The specific or "eradicant" action of the vapor, withrespect to the parasite, is demonstrated. Photographs ofthe disease, methods of field investigation and the effectsof environment on the use of paradichlorobenzene vaporsare shown. Application of these investigations to thecontrol of tobacco downy mildew on the farm is illus-trated. In attendance will be Dr. J. A. Pinckard, RuthMcLean and associates.

W. M. WELCH SCIENTIFIC COMPANYChicago

Booth No. 51The exhibit of the W. M. Welch Scientific Company

will show, among many other special designs, samplesof different sizes and rulings of Wood's Replica Diffrac-tion Gratings with brilliant spectra concentrated in thefirst order; a new all stainless-steel No. 4030 Balance with110-gram capacity and 1 centigram sensitivity; a newSlide-wire Rheostat with special, non-inductive Coorsporcelain tube; A. H. Compton Chart of ElectromagneticRadiations; and a new series of Lecture-table Meters forsimultaneous reading-complete D.C. Voltmeter and Am-meter in the same case, and the same combination withA.C. instruments.

JOHN WILEY AND SONS, INC.New York

Booth No. 40The display will consist of the recent books published

in all the fields of science and technology covered by thepublications of the company. May we suggest that par-ticular attention be given to the following important newbooks:-Burk 's "Catalysis "; Lindsay 's "General Physiesfor Students of Science"; Loeb's "Fundamental Proc-esses of Electrical Discharge in Gases "; Mayer andMayer's "Statistical Mechanics"; Turner and Henry's"Growing Plants in Nutrient Solutions"; Zworykin andMorton 's "Television." The company will be repre-sented at the exhibition by Mr. R. C. M. Gould, Mr. J. K.Maddock, Mr. R. A. Buckles, Jr., and Mr. K. G. Getman.

WILKENS-ANDERSON COMPANYChicago

Booth No. 54High-lights of the WACO exhibit are the Semi-micro

equipment for qualitative and organic chemistry, in whichthis company has pioneered. The KWSZ Photometer,developed at Purdue University, will be on display, andin this connection a 24-page booklet with abstracts ofrecently published technics, involving determinationsusing photo-electric colorimetry, will be distributed. Thenew Cameron pH Tester, as well as the more elaborateCameron pH Meter, will be shown ... both instrumentsuse the glass electrode. Other equipment in the ChemicalLaboratory Apparatus line, new and different, will occupythe balance of the space. Mr. F. A. Anderson and Mr.W. C. Burfischer will be in charge.

THE WILLIAMS AND WILKINS COMPANYBaltimore

Booth No. 90The Williams and Wilkins Company will display their

complete group of 19 scientific periodicals as well as theirmost recent books. Among recent books are "An Outlineof Physiology'" by Amberson, "Bergey 's Manual ofDeterminative Bacteriology" (5th edition), "Sex andInternal Secretions" (2d edition). Several new booksin veterinary science will also be shown. Mr. E. F. Wil-liams will represent the firm at the exhibit.

DECEMBER 22, 1939 -SCIENCE-ADVERTISEMENTS 11

12 SCIENCE-ADVERTISEMENTS

NEW LRM BALOPTICON for Lantern Slides and Opaque Material

TWO NEW BALOPTICONSWith Three Desirable Features

THE new Balopticons ERM and LRM have threeoutstanding advantages. First-Standard Bausch &Lomb Optical Quality,-brilliantly sharp screen im-ages of projected material under actual class roomconditions.Second-An improved Built-In Blower-Cooling

System of high efficiency. The blower in these twonew Balopticons is completely enclosed. It is locatedin front of the base and forces a current of cold airover the material being projected. This cooling sys-tem is out of the way of the operator, and does not

hinder access to any part of the projector while in use.Third-An improved object holder for opaque ma-

terial, permitting projection of 6" x 6 /8" areas. Aspecial feature of this holder is its freedom from ob-structions that would interfere with the projection ofselected portions of large sheets, maps or drawings.The door is provided for the placing of solid objectsin the projection area.A new folder E-132 describing these two models

in detail will be sent on request, Bausch & LombOptical Co., 642 St. Paul Street, Rochester, N. Y.

BAUSCH & LOMBFOR YOUR EYES, INSIST ON BAUSCH & LOMB EYEWEAR, MADE FROM BAUSCH A LOMBGLASS TO BAUSCH & LOMB HIGH STANDARDS OF PRECISION a .a a * ....

12 SCIENCE-ADVERTISEMENTS VOL. 90, NO. 2347

VOL. 90, No. 2347

air compressors of smaller sizes pump so little air thatthey are likely to be inadequate for future require-ments. Compressors of sufficient capacity to meetprobable future needs are expensive. With thethought that it will later be replaced by a large com-pressor or by one such as that described in this jour-nal,2 an aerating system made as follows has beenfound very satisfactory. Its chief appeal is its verylow cost. Most of the necessary equipment may befound in the laboratory and in the junk yard.A Kellogg pump which was regular equipment on

an old model Cadillac car (SJ series) was mountedon a heavy wooden frame. A twelve-inch V belt pul-ley was substituted for the gear on the pump. Thistogether with the standard size three-inch pulley on ai H.P. electric motor gave the pump a speed of about400 r.p.m. A three-gallon spray tank was mounted onthe same frame immediately above the motor. In orderto reduce friction and avoid breakage of a metal tube,a heavy cloth-reinforced rubber hose was used to carrythe air from the pump to the tank. The outlet fromthe tank connected with suitable reducers to a two-inchpipe twelve inches long filled with cotton-as a pre-caution against oil getting into the solutions.

This compressor,3 which was assembled withoutexpenditure for technically skilled labor and at nocash outlay except for the belt and the twelve-inchpulley, has supplied for three months continuous aera-tion for 120 containers (ranging in size from threequarts to three gallons) with pin-punctured rubbertube aerators. When fewer solutions are aerated theair pressure is regulated by the simple expedient ofby-passing air through a rubber tube partially closedwith a screw clamp.

Because the pressure in the entire system is depen-dent on all the lines remaining intact, it has been founddesirable to use five-sixteenths-inch glass T tubes withgrooved ends for one-quarter-inch rubber tubing usedin the air lines.

G. J. RALEIGHCORNELL UNIVERSITY

A CONVENIENT METHOD FOR OBTAININGBLOOD SERUM

SERUM is used for a number of chemical analyses andis usually obtained by permitting a tube of blood toclot. The serum is obtained after freeing the clotfrom the walls of the tube by a thin knife or fine glassrod, which is insinuated between the clot and the wallsof the tube and then passed around the clot. The tubeis then centrifuged or allowed to stand until the clotshrinks sufficiently to liberate enough serum.

2 H. W. Beams, A. T. Casteel, R. L. King, SCIENcE, 86:428, 1937.

3 The pump was furnished by F. W. Barrett, and theassembly was made by C. J. VanEtten.

In carrying out these manipulatiotls, the clot is fre-quently injured and the serum is often contaminatedwith cells, either intact or hemolyzed. The followingmethod avoids all trauma to the clot.A test-tube or centrifuge tube of suitable size is

waxed on its inner surface by filling it with molten'wax and pouring out the excess. The tube is allowedto cool while rotating it so as to spread the waxuniformly on its walls. After the wax has solidified,a small pledget of dry cotton is placed at the bottomof the tube by means of a glass rod. The tip of thetube is then placed in the Bunsen flame momentarily.The wax melts and secures the cotton to the bottomof the tube.The tube is filled in the usual way. The cotton

serves to initiate clotting and to fix the clot to the bot-tom of the tube. Then, as the clot shrinks, it will bewell away from the surface of the blood, since it doesnot stick to the waxed walls. The serum can bepipetted away from the clot or poured into a suitablevessel, the clot remaining in the tube.

E. M. ABRAHAMSONTHE JEWISH HOSPITAL,BROOKLYN, N. Y.

BOOKS RECEIVEDBENNETT, H. Standard Chemnical and Technical Diction-

ary. Pp. xlii + 638. Chemical Publishing Co. $10.00.Carnegie Corporation of New York. Beport of the Presi-

dent and of the Treasurer, 1939. Pp. 167. The Cor-poration.

CLAPP, ELSIE R. Community Schools in Action. Pp.xviii + 429. Illustrated. Viking Press. $3.75.

GERS11ENFELD, Louis. Biological Products. Pp. xliv +236. Illustrated. Romaine Pierson Publishers, NewYork. $4.00.

Hou, H. C., and others. Chinese Medical Association,Report Series No. 12: Nutritional Studies in Shanghai.Pp. 92. The Association, Shanghai. $1.00.

LAMB, FRANK H. Book of the Broadleaf Trees. Pp.367. Illustrated. Norton. $3.75.

MATLIN, D. R. Growing Plants without Soil. Pp. 137.Illustrated. Chemical Publishing Co. $2.00.

MILLIKAN, R. A. Cosmic Bays. Pp. 134. 42 figures.Macmillan. $2.50.

SCHNEITER, CARL. Die Skelette aus den Alamannen-grabern des Ziirichsee-, Limmat- und Glattales (in-klusive Greifensee- und Pfajllkerseegebietes). Pp. 148.8 plates. Anthropologischen Institut der Universitat,Zurich.

SHEPPARD, W. F. British Association for the Advance-ment of Science Mathematical Tables, Volume VII:The Probability Integral. Pp. 34. Cambridge Uni-versity Press, Macmillan. $2.50.

Svenska Linn6-Sdllskapets Arsskrift. Jrg. XXII, 1939.Pp. 148. Illustrated. Almqvist and Wiksells, Upp-sala.

TURNER, WAYNE I. and VICTOR M. HENRY. GrowingPlants in Nutrient Solutions; or Scientifically Con-trolled Growth. Pp. xiii + 154. 29 figures. 3 plates.Wiley. $3.00.

WRIGHT, W. D. The Perception of Light: An Analysisof Visual Phenomena in Belation to Technical Problemsof Vision and Illumination. Pp. 100. 49 figures.Chemical Publishing Co. $2.50.

598 SCIENCE

DECEMBER 22, 1939 SCIENCE-ADVERTISEMENTS

NEW WILEY BOOKSfWhen attending the A.A.A.S. meetings 11.

at Columbus, visit our booth, No. 40. MGENERAL PHYSICSFOR STUDENTS OF SCIENCEBy ROBERT BRUCE LINDSAY, Hazard Professor of Physics, BrownUniversity.This textbook is intended for an introductory course in college physics,for sophomore students of science who have had mathematics throughelementary calculus, or for a course for students who have already hadan elementary non-mathematical course in physics, as an intermediateand more thorough treatment.Ready in January 534 pages; 265 illus.; 6 by 9; $3.75

-___ FUNDAMENTAL PROCESSES OFELECTRICAL DISCHARGE IN GASESBy LEONARD B. LOEB, Professor of Physics, University of California.This volume relates modern atomic physics to the field of dischargethrough gases. The topics chosen, aside from the chapters dealing withdischarges, are designed to present the fundamental processes active inall discharge phenomena in both the evolutionary and present-day stages.Published in December 717 pages; 297 ilus.; 6 by 9; $7.00

TWELFTH REPORT OF THECOMMITTEE ON CATALYSISNATIONAL RESEARCH COUNCIL.A particularly timely book because of the tremendous interest now beingshown in catalysis in industrial fields. The material in the report is theresult of original research and much of it appears here for the first timein any book.Ready in January Approx. 336 pages; 6 by 9; Probable price, $5.00

AN INTRODUCTION TOCHEMICAL SCIENCEBy W. H. HATCHER, Professor of Chemistry, McGill University.An exact, yet cultural survey, stressing economic features and presentingorganic chemistry visually. No field of chemistry is ignored, yet thetreatment is not superficial. The book is intended for use in a complete,non-specialist course for liberal arts students.Ready in January 423 pages; 66 illus.; 5i by 8i; $3.00

INTRODUCTORY COLLEGE CHEMISTRYBy NEIL E. GORDON, Professor of Chemistry, Central College; form-erly Professor of Chemical Education, The Johns Hopkins University;and WILLIAM E. TROUT, JR., Professor of Chemistry, Mary BaldwinCollege.This volume offers an unusual integration of text, laboratory manual andworkbook. Directions for experiments are given, with blanks for thestudent's records. The arrangement does not preclude the use of a sep-arate notebook. Principles are stressed, rather than applications.Ready in January Second edition; 753 pages; 159 illus.; 6 by 9; $3.50

JOHN WILEY & SONS, INC.440 FOURTH AVENUE, NEW YORK, N. Y.

13

SCIENCE-ADVERTISEMENTS

DUO-SEAL TWO STAGE VACUUM PUMPThis Vacuum Pump, although smaller than the 1405 which has made such phe-nomenal service and endurance records, has the same internal vane movementsand other important mechanical features.

FIVE SPECIAL FEATURES1. The proper pump speed is approxi-mately 475 R.P.M., which produces afree air capacity of nineteen liters perminute.2. Each pump is tested on our certi-fled McLeod gauges to less than 01micron (.0001 mm Hg) and many reg-Ister less than .07 micron.8. The mechanical action Is unusuallyquiet for a vacuum pump.4. The exhaust chamber is arranged

the collection of gases where thisis desired._L The oil level Is visible and the

oil can be conveniently drained.Positive oil seal-no oil can back

*ulp.

No. 1400BNo. 140OB-DUO-SEAL VAC-UUM PUMP, Two Stage, Motordriven. Mounted on a cast Ironbase with 4 H.P. 110 volt A.C.motor and V belt with belt tight-ening device. Each, $85.00No. 1400-DUO-SEAL VAC- NV. M.Welch ScieniUUM PUMP, Two Stage, with Established 181pulley but without belt, motor or 1517 Sedgmick street

...................................O0............1gnwyc

Catalog li8st over 10,000 itemsfor Science Laboratories.

WRITE FOR ITIncludes many new and

interesting pieces

tific Companyh0

Chicago. I11inois.U.S.A

AVAILABLE FOR INVESTIGATORSIN THE VITAMIN FIELD

Pyrazine-2, 3-dicarboxylic acidPyrazine monocarboxylic acid2-methyl-1, 4-naphthoquinonePhthiocol (2-methyl-3-hydroxy-1, 4-naphthoquinone)

These chemicals, prepared in our research laboratory, willbe supplied to qualified investigators upon application.

MEAD JOHNSON AND COMPANYEVANSVILLE, IND., U.S.A.

NEW

DiEcimMBF,R 22Y 1939 15

DEEME 22 99SINEADETSMNS

LABORATORYSUPPLIES

AMERICAN-MADE GIEMSA STAINfor blood smears.

We manufacture a high gradeGIEMSA STAIN.

$2.00 for 2 ounces.

Stains and Reagents carefully made andtested on actual cases.

Write for Catalogue.

GRADWOHL LABORATORIES3514 Lucas AvenueSt. Louis, Missouri

MONOGRAPHS AND SYMPOSIA OF THEAMERICAN ASSOCIATION FOR THE

ADVANCEMENT OF SCIENCE1. The Protection by Patents of Scientific

Discoveries. 40 pages (out of print) $ .502. Physical and Chemical Changes in

Nerve During Activity. 29 pages; 7graphs, 7 tables (out of print) ..................... 50$ 0

3. The Scientific Aspects of Flood Control.47pages;35Mustrations ............................. $ .50

4. Some Fundamental Aspects of the Can-cer Problem. 248 pages; 66 illustra-tions .... ... $2.50

5. Tuberculosis and Leprosy-The Myco-bacterial Diseases. 133 pages; 40 Il-lustrations ...... $2.50

6. Syphills. 193 pages; 39 Mustrations .. $2.507. (a) Applcations in Surface Chemistry

and (b) Recent Advances in ChemicalPhysics. 133 pages; 21 Mustrations... $2.50

8. The Migration and Conservation of Sal-mon .................... $2.00

9. Mental Health. Cloth binding, 106pages,20 maps, 1 graph .......................... $3.50

10. Problems of Lake Biology ........................... $2.0011. The Gonococcus and Gonococcal Infec-

tion . ..... $2.50The Science Press, Lancaster, Pa.

The Academy of Natural Sciences isproud to announce the publicationof Monograph Three by its distin-guished Curator of Mollusks

LAND MOLLUSCA OFNORTH AMERICA

(North of Mexico)

BY HENRY A. PILSBRYA complete systematic and distributional study ofland mollusks of North America, containing manydescriptions of new genera and species, as well asvitally important original drawings of the softanatomy.

In two volumes, the first being divided into twoparts, Part One, now ready, contains illustrationsof 2,000 specimens in 599 pages. Price by sub-scription, $7.50, payable with order.

Vol. I, Part Two, in pressVol. II, in preparation

Subscription to Vols. I and II, $25.00.

Orders or requests for announcements should besent to: The Secretary, The Academy of NaturalSciences, 1900 Race Street, Philadelphia, Pa.

TAYLOR NON-FADING LIQUIDColcor Standards

Taylor Slide Compara.tors, with guaranteed

non-fading liquid colorstandards, are ideal for

general pH and chlorinecontrol and for control

K _ | 1 - of phosphates in boilerwater.

Molded from plastic,work on the slide prin-ciple.

Z 1 Full information onComparators and Cole-man Glass Electrode.

W. A. TAYLOR & CO., INC.891 Linden Ave. Baltimore, Md.

U',Scientists, authors, lecturers, travelers and thou-sands of men and women in all walks of life havemastered a new language in their own homes bythe world famous LINGUAPHONE METHOD.. . . Amazingly simple, thorough, sound, no smat-tering. 27 languages available.

Send For FREE Book.LINGUAPHONE INSTITUTE

59 R.C.A. Buflding New York City

-

-

=-

-

DECEMBEF, 22, 1939 SCIENCE-ADVERTISEMENTS 17