you needn't put up with"shoebox" block filing

The "Lab-aid" paraffin block filing cabinet is finishedto match all other types of "Lab-aid" files, and stacksiterchangeably with any of them: Here it is stackedupon a vertical microslide file with 1" drawers.

Ask for a six-month-old paraffin block in many an

otherwise well-ordered laboratory, and the hunt's on.

Likely as not it means hours of prowling through a

weird behind-the-scenes jumble of dusty, dog-earedcartons . . . trying everyone's temper, taking every.

Qne's time, piling up hidden costs.That's all out now, with this new "Lab-aid" block

filing cabinet. You file your paraffin blocks in small,shipshape, white cardboard boxes, which come invaried sizes to accommodate all sorts of blocks, how.

ever irregular or out-sized. The boxes knock down,but spring to shape in a moment, so they're no

storage problem. They're so proportioned thatthey fit snugly, row on row, in the shallow steel

drawers.The all-steel cabinet holds ten drawers, equipped

with combination.drawer-pulls and label-holders ateach end. Each drawer will accommodate a gross ofthe 1A"/2" boxes: other sizes in ratio (see the filleddrawers above). Multiply that by ten and you'vesome idea of the large capacity of this compact sec-

tion (it's only 19" square by 12" high) . That'sbecause there's no waste space . . . every cubic inchis a filing inch.

laboratory essential

The "Lab-aid" laboratory filing systemcomprises a range of versatile equipmentwhich brings new standards of filing effi-ciency to the pathologieal laboratory. Fora descriptive bulletin, please use thecoupon below.

The TECHNICON Company215 E. 149th St., New York 51, N. Y.

E] Send me particulars of the new "Lab-aid-"paraffin-block file.

El Send me complete "Lab-aid" filing systembulletin.

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

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

City .State. I

Testing for sound lost betweentelephone receiver and ear. Manysubjects were used in these tests.

How to compensate for

a curl... and add to

gour telephone value

Bell scientists know that the telephoneis not used under ideal laboratory con-

ditions. There is never a perfect sealbetween receiver and user's ear. A curlmay get in the way, or the hand relaxa trifle. And ears come in many shapesand sizes. So some sound escapes.

Now, sound costs money. To delivermore of it to your ear means biggerwires, more-amplifiers. So Bell Labo-ratories engineers, intent on a thriftytelephone plant, must know how muchsound reaches the ear, how much leaksaway. They mounted a narrow "sam-pling tube" on an ordinary handset.

Automatic recorder plots sound pressures de-veloped in the ear canal at different frequencies.

The tube extended through the re-

ceiver cap into the ear canal. As soundsof many frequencies were sent throughthe receiver, the tube picked up a por-tion, and sent it through a condensermicrophone to an amplifier. That sam-

pling showed what the ear received.As a result, Bell scientists can com-

pensate in advance for sound lossesbDuild receivers that give enoughsound, yet with no waste. That makestelephone listening always easy andpleasant.

It's another example of the way BellTelephone Laboratories work to keepyour telephone service one of today'sbiggest bargains.

BELL

TELEPHONE

LABORATORIES

Working continually to keep your telephoneservice big in value and low in cost.

-EEI-u W

11-

I..

Three NEW icul Texts and References.. . exceiet in respects

BOTANYby R. DARNLEY GIBBS,

McGILL UNIVERSITY

* A NEW text featuring the phylogenetic approach to the subject-from the simplest to the most complex.

Algae, fungi, lichens, bryophytes, vascular plants, and seed plantsare presented in their logical order. Each subject is covered withclarity and continuity. The text is unusually well balanced in theamount of material presented and in the emphasis placed on eachsubject.

Designed for a full year's course in college botany, it includes manyphotographs and drawings by the author from living material actuallystudied. Dr. Gibbs has thoroughly integrated text and illustrations intoa comprehensive book easy to use in any locale.

Effective teaching aids include floral diagrams of the importantflowering plants, an excellent and brief account of the development ofplant physiology (especially the history of photosynthesis), and anoutstanding description of plant pigments-their origins, compositionand functions.The modern accepted classification of plants is followed throughout

and an extensive and complete index is included for easy reference.261 Illustrations-118 Plates-554 Pages-$6.00

ME^E^**A.EhAV J * A complete and orderly treatment of the structures, life historiesMUO rPULUOGY an and classifications of all the important groups of fungi. Both a text and

reference, it is written by the foremost mycologist in the country today.TAXONOMY of FUNGI The new and specially prepared drawings are invaluable aids in thestudy of the subject. Each chapter is concluded with a list of keys to

by ERNST A. BESSEY, the orders, families and genera of the particular group discussed. Thisfeature alone makes the book an indispensable aid in teaching and

DEAN EMERITUS OF THE SCHOOL research. Of great importance is the 96-page guide to the literature forOF GRADUATE STUDIES, MICHIGAN the identification of fungi, and the references at the end of each

OF GRDUATESTUDIS, MIHIGANchapter.STATE COLLEGE

GENES, PLANTSand PEOPLE

by C. D. DARLINGTONand K. MATHER,

JJOHN INNESHORTICULTURAL INSTITUTION,

LONDON

210 Illustrations-791 Pages-$7.00

* An interesting collection of essays on genetics that have beenwritten by two authors over a period of twenty years when both wereworking to solve the same problems from different points of view. Thearticles were written individually but have a unity of purpose.The essays deal with plants and animals, medicine and agriculture,

and offer new interpretations of evolution, development and disease.Several articles discuss the controversy between the genetic theorybased on the traditional scientific method and that propounded by thelatest Soviet school represented by T. D. Lysenko.

13 Figures-187 Pages-$4.00

Use This Handy Coupon To Order Your Copies Today!

The Blakiston Company, 1012 Walnut Street, Philadelphia 5, Pa.Please send me the following:Ql Gibbs' "Botany" for a teacher's examination; a personal useD Bessey's "Fungi" for a teacher's examination; 5 personal useO Darlington & Mather's "Genes, Plants & People" for

El teacher's examination; F] personal use

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

Department.............................................School .....................................................................Address .......................................................................

City.Zone.. State.Sci. 3-30-51

In Canada-Write-105 Bond Street, Toronto 2

SCIENCE, Vol. 113

iII

0

I

III

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

2

* A basic necessity for every nuclearlaboratory is a beta-gamma monitor-ing instrument for checking benchand desk tops and determining safeapproach distances. The NuclearModel 2610A portable providesyour laboratory with dependableprotection against the harmful ef-fects of radioactive isotopes andX-rays. You can make easy routinechecks of every inch of your lab be-cause the 2610A is arranged forfingertip control. The removableprobe snaps into the handle for con-venience. The proven circuit in a

waterproof case gives you the reli-able monitoring you demand forcomplete laboratory safety.The 2610A is another of the many

developments with which Nudearengineers continually meet theever increasing demands of nuclearscience.

nuclear INSTRUMENT andCHEMICAL CORPORATION217 West Kris Street,Chic"" 10, Il.

SCIENCE, Vol. 113

P H O TO V O L TExposure Photometer Mod. 200-M

for

PHOTOTMI -C ROG R?A PH Y

Accurate determination of exposure time inblack-and-white and color photomicrography

Write for Bulletin #810 to Price $65.-

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

A

flewJ ffl04,y I?ooA§

IVillis'THE PRINCIPLES OF PATHOLOGY

A great need in the literature on pathology is met with this new book, for it embraces the WHOLEof pathology-expounded from its general principles. This approach greatly facilitates the use of thebook either clinically or for research, for descriptions of lesions in the various organs are included inthe accounts of the general processes and principles which they exemplify.Willis has also incorporated all essential details regarding regional peculiarities of particular diseasesand has made the information easily accessible by means of plentiful cross references and a fullindex. Conforming to the plan of the text, most of the 300 photographs and diagrams illustrategeneral principles rather than diseases of particular organs.The book is beautifully literate-and of course purely scientific. It includes notes on the meaning ofnames, the history of pathology and the art of observation that will be of the utmost value to thereader. Willis writes with the skill of a great teacher-that is, one who imparta knoweldge such asto make it a pleasure as well as a duty to absorb.

By R. A. WILLIS, D.Sc., M.D., F.R.C.P., Professor of Path-ology in the University of Leeds. 722 pages, 288illustrations. Price $12.00.

Nicholson'sSTUDIES ON TUMOUR FORMATION

Doctor Nicholson was among the greatest histopathologists the world has known. His studies inpathological- anatomy were renowned for their versatility as well as for the amount of informationthey contained.The source of his material in STUDIES ON TUMOUR FORMATION was the surgical wards ofGuy's Hospital, London, where he was Clinical Microscopist. His twenty "Tumour Studies" whichappeared in Guy's Hospital Reports were considered classics. Just as Nicholson was persuaded toprepare his material in book form, he died.In this volume, therefore, his "Tumour Studies" are reprinted in the original form-with no attemptto change or modify them. All of Nicholson's drawings appear and no care or expense has beenspared in reproducing these illustrations.Anyone reading these Studies for the first time can be assured that along with an abundance of re-liable factual information, he will find much that is arresting and entertaining-for Nicholson was agreat philosopher and a gifted writer, as well as a studious biologist and pathological anatomist. Therange of his subjects is astonishing, and his observations make one of the finest books it has beenour pleasure to present to the profession.

By the late G. W. DeP. NICHOLSON, M.A., M.B., B.Ch.,Professor of Pathology, Guy's Hospital, London. 637pages, illustrated. Price, $15.00.

The C. V. Mosby Company Sci 3.30ORDER 3207 Washington Blvd.

FORM St. Louis 3, Mo.FORM ~~~~~~~~~~~Pleasesend me:Willis' THE PRINCIPLES OF PATHOLOGY-$12.00

Nicholson's STUDIES ON TUMOUR FORMATION-$15.00Enclosed fin7d check. Charge my account.

Name---------------

Address --------------------- -----

March 30, 1951 5

New ReprintCa1a/o74 wXAvailable April, 1951

I /l/lenumIZ{/fiver3a/. By ALEXANDER ZAHLBRUCKNER

Alexander Zahlbruckner's major work, Catalogus lichenum universalis, consists ofsome 7,900 pages of references to families, genera, and species of the class Lichenes.This work, published in ten volumes with one index volume, was begun in 1922 andcompleted in 1940. It includes all references up to 1940 on lichens and their synonymy,thus making it a concise and complete bibliographical guide. It also includes the vari-eties and forms of about 15,000 species.

All the references pertaining to lichenological publications now scattered throughthe literature are brought together here. Students of lichenology and closely relatedfields, especially those in charge of curating private or public herbaria, will find thisset a "must" in order to enable them to cite literature, trace synonyms, ascertain propertaxonomic relationships, and, in general, to answer a multitude of questions. Sincethe complete original work is very difficult to obtain, its reproduction will add im-measurably to our now inadequate basic reference material in lichenology.

9 Volumes and Index Volume, Berlin, 1922-1940, 7,360 pagesCloth bound set, $185.00

JOHNSON REPRINT CORPORATION125 East 23 Street, New York 10, N. Y.

U~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Automatic Tidal Volume Recorder GLASS ABSORPTIONPeck-Waller CEL bAmadeLTT

Makers of Complete Electrophoresus ApparatusRelieves investigator of constant supervision. . . Resra SCIENTIFIC APPARATUStory rates of 2-60 per minute, and tidal volume of 2W cc | Klett-Summerson Photoelectric Colorimeters-to 400Icccan be recorded. Colorimeters- Nephelometers- Fluorimeters-WRITE: Bio-Colorimeters- Comparators - Glass Stand-

Phipps & Bird In. l ards-Klett Reagents.Phipps BiDrd Inc.l lP. O. Box 2-V-Richmond 5 Va. Klett Manufacturing Co.

179 East 87 Street, New York, New York

SCIENCE, Vol. 1136

HELLIGE -TRAUBESTALAGMOMETERFOR DETERMINATION OF THE SURFACE TENSION OFBLOOD AND OTHER FLUIDS BY THE DROP METHOD

1210 Complete in Wooden Case with 3Tubes, one for blood and other viscous fluids,the other two for small and for large quan-tities of thin liquids .............. $40.00

WRITE FOR CATALOG No. 1210

HELLIG EI N CO R P O RAT E D

3718 NORTHERN BLVD., LONG ISLAND CITY 1. N.Y.

Hundreds of users in laboratory, field and factory now makefluorescent checks quickly and easily-in broad daylight-withthe Menlo Fluoretor (blacklight).Exclusive dark chamber holds comparison test tubes, solidsamples, powders or fluids. Neoprene viewing cone excludessurrounding light for examination of large areas.Choice of filtered 2537 or 3650-63 Angstrom frequencies;interchangeable head for alternate frequency. Transmissioncurve with every instrument. Standardized mercury-vapordischarge tubes. Instant-starting, troublefree. Portable-weighsless than 2 pounds, ready to use. Models for operation fromeither two standard flashlight batteries or 110-120 v AC.Write for brochure, data on U-V ise in your field.

MENLO RESEARCH LABORATORYDrawer A-4, Box 522,, Menlo Park, Calif.

DEALER INQUIRIES INVITED

Reg. U. S . Pa.Of

DL-homocysteine (free base)DL-homocystineDL-homoserine

hydroxy-L-prolineDL-isoleucineL-isoleucine

DL-lanthionineDL-leucineL- leucine

DL-lysine HydrochlorideL-lysine Hydrochloride

D-methionineDL-methionineL-methionineDL-norleucineDL-norvaline

DL-ornithine HydrochlorideD-phenylalanineDL-phenylalanineL-phenylalanine

L-prolinesarcosineDL-serine

sodium glutamate, mono 99%taurine

DL-threonineDL-tryptophaneL-tryptophaneDL-tyrosineL-tyrosineDL-valine

SEE SCIENCE MARCH 16 ISSUEFOR ADDITIONAL LISTINGS

Use this catilo2 as a "one stop" source of I:t@I/L1\Amino Acids, Vitamins, Carbohydrates,Adenylates, Nucleates, Purines, Pyrimidines,Enzymes, Microbiological and Bacterio- WRITE FORlogical Media, Complete Animal Test Diets YOUR COPYand Ingredients for investigational use. TODAY

GBI 60 LABORATORY PARIsCHAGRIN FALLS, ONH

March 30, 1951

-i

0 0

0

7

3NDigmip

overMore TeachingInstruents

LOW initial cost! Wider range of practical applica-tion than any other comparable instruments!

Sturdy construction for years of hard, daily use!These important factors mean more Bausch & Lombadvantages for your students . . . within your budget.B&l "FL" MICROSCOPE. No other student microscopeoffers so many advantages in teaching proper micro-scope technique easily and quickly at low cost.Catalog D-185.B&l TRIPLE-PURPOSE MICRO-PROJECTOR. (1) Projectspermanently-mounted specimens. (2) Projects im-ages directly onto notebook for accurate tracing ordrawing. (3) Projects live specimens in liquid.Catalog E-20.IlL MODEL LRM BALOPTICON PROJECTOR. Projects large,clear, brilliant images of conventional or student-made slides . . . AND of opaque objects, printed

' material, photographs, large biological specimens.Catalog E- 1 1.A Bausch & Lomb sales engineer will be glad to

help you get the most value, the most practical teach-ing advantages, out of your budget. No obligation,of course.

WRITE for free demonstrations and for completeinformation. Bausch & Lomb Optical Co., 642-5St. Paul St., Rochester 2, N. Y.

SCINCE, Vol. 113