how Lab-aid's

a5g 9 c filing sts . . .saves floor space

How can a "'Lab-aid" filing cabinet packso much in so little space?

Look at one to see. You'll find no thickbulkheads between drawers, no space-consum-ing buttresses, no bulky tracking guides.

Every cubic inch inside is a hard-working"storage inch." The patented "Lab-aid" con-struction gets fourteen full-length drawers ina cabinet only 19" square. Yet, close-set asthey are, every drawer slides straight and true,easily, smoothly, without binding.

Drawers are freely interchangeable, too.Use 1 ", 2", and 4" capacity full-length drawersin the same unit, in.any arrangement you want,

... because e

for microslides, transparencies, lantern slides,cards, etc. And use any of them anytime forspaced filing instantly. Lift out the separator,and you clear the drawers for close-packedstorage.

Other units in the "Lab-aid" line providefor flat-filing microslides . . . for filing paraffinblocks, for "frame-spread" transparency filing.All are staunchly built of heavy gauge steel,strongly welded throughout. All have the samebasic 19" square dimension, so they stackrigidly to any convenient height.

Write for the catalog describing these

uniquely effitient "Lab:aid" filing cabinets..

.very inch is a filing inch

laboratory filing equipmentTHE TECHNICON COMPANY

Chauncey, New YorkThese same Cabinots are mansfactored hy oar French CwrpatinsCOMPAGNIE TECHNICON * 7 rue Geores Vllb * Paris

CONTRASTequipment

Without staining and without specimen destruction the differentiation of fine structural details is in manyinstances made possible only by viewing microscopic objects with Leitz PHASE CONTRAST.

Only Leitz PHASE CONTRAST Equipment with the unique Heine condenser permits instantaneous and contin-ual transition from bright field to phase contrast and to dark field. Use of polarizing filters with PHASE CONTRASTpermits observation of anisotropic effects.Within seconds this transition is easily performed by turning the condenser knob, thus changing the light pathas required and permitting comparative study of structures visible in phase contrast with those seen under brightor dark field.

Leitz PHASE CONTRAST Equipment can be used with any microscope. The Leitz DIALUX, as illustrated, with LeitzPHASE CONTRAST Equipment is an ideal combination.

E. LEITZ, INC., Dept. SC.-8

468 Fourth Ave., New York 16, N. V.

z Please send me the PHASE CONTRAST Equipment brochure.

Name

s S_ - ^ L ~~~~~~~~~~StreetCity Zone State.

09055

E LEITZ, INC., 468 FOURTH AVENUE, NEW YORK 16, N. V.

Distributors of the world-famous products of Ernst Leltz, Wetzlar, Germany

CAMERAS * LENSES * MICROSCOPES * BINOCUL^RS

SCIENCE is published weekly by the AAAS, 1515 Massachusetts Ave., NW, Washington 5, D. C. Entered at the Lancaster, Pa., Post Office as second classmatter under the act of 3 March 1879. Annual subscriptions: $7.50; foreign postage, $1; Canadian postage, 50e.

;26 AUGUST 1955 355

54Ire oCac e3t

ANNUAL REVIEWS

BIOCHEMISTRYVol. 24 (July 55)

PLANT PHYSIOLOGYVol. 6 (June 55)

PHYSICAL CHEMISTRYVol. 5 (Sept. 54)

NUCLEAR SCIENCEVol. 4 (December 54)

PHYSIOLOGYVol. 17 (March 55)

MEDICINEVol. 6 (May 55)

PSYCHOLOGYVol. 6 (Jan. 55)

MICROBIOLOGYVol. 8 (Oct. 54)

Back Volumes Also Available

$7.00 postpaid (U.S.A.); $7.50 postpaid (elsewhere)

ANNUAL REVIEWS, INC.Stanford, California

356

ADENOSINE and its phosphate esters havemarked vasodilating properties. Literature cita.tions available on, for example:ADENOSINE-5-PHosPHoRic ACID* in cases ofarteriosclerosis obliterans, vascular disease, vari-cose and phlebitic veins, intermittent claudica-tion, vasodilation and atherosclerosis.ADENOSINE TRIPHOSPHATE * in cases of cardio-vascular disease and for studies of vasodilation,muscle action and fatty acid metabolism.

ADENOSINE-3-PHOSPHO1C AcE for vasodilationand periphercl ailments.*Available as Lycedan® **Available as TriphosesonS

These Schwarz biochemicals are of highest purity,and their quantity production provides ample sup-plies at low cost. Write for informative technicalbulletins, complete specifications and references toliterature. SL318

SCHWARZ LABORATORIES, INC.Manufacturers of Fine Chemicals

230 Washington Street, Mount Vernon, N. Y.

SCIENCE, VOL. 122

ZYMOSANA PRODUCT OF

THEFLEISCHMANNLABORATORIES

Available for

Research PurposesFor use as an immunological reagentfor isolation of properdin from bloodsera and in animal investigations

Write for information and prices

SPECIAL PRODUCTS DIVISIONSTANDARD BRANDSINCORPORATED

595 Madison Ave., New York 22, N. Y.

A4-AcetylaminoantipyrineAcetylcholinesterase

2-AcetylthiopheneAcetyl-DI-Tryptophan

4-AminoantipyrineL-Aspartic AcidAzosulfamideFor the rest of the Winthrop Alphabet

send for our 1955 pr:ce list.

WINTHROP

INC.

SPECIAL CHEMICALS DIVISION1450 Broadway, New York 18, N. Y.

IILi

LL

For Exceptional

Quantitative

Results In

Micro-Analysis in

PA-PER CHROMATOGRAPHY

Use The WELCHl

DENSICHRON

Consists of Densichron,

TRANSMISSIONDENSITOMETER

Probe, and Transmission Light Source

No. 3835B Patent No. 2424933

TRANSMISSION LIGHT SOURCE UNIT. This is an enclosed * DENSICHRON WITH BLUE OR RED PROBE. This consistslight source powered by a constant-voltage transformer and of the amplifier with logarithmic-scale meter, blue or redequipped with a hinged arm for supporting the Densichron sensitive probe, metal probe support, five differen measuringprobe. The plate or film to be observed is placed over theaperture and the probe is lowered into position for a reading. apertures, a cone with i/s-nch aperture, and a set ofSuitable controls are provided. It operates on 115 volts, 60 instructions. The amplifier operates on 115 volts, 60-cyclecycles, A.C. A.C., only, except on special order.

It has been found that, because of the differential migration of the solutes through filter paper themaximum color density of the paper is proportional-to -the concentration of -material. The "no drift" fea-ture and the high sensitivity of the Densichron provide measurements of excellent repeatability with ac-curacies having high statistical significance. It has been successfully used for amino acids, sugars,vitamins, steroids, hormones, drugs, and an endless variety of both organic and inorganic compounds.

Write for literature describing the production of papergrams and the use of the Densichron forquantitative determination by the maximum density method.

No. 3835B Complete $425.00

W. M. WELCH SCIENTIFIC COMPANYDIVISION OF W. M. WELCH MANUFACTURING COMPANY

ESTABLISHED 18801515 Sedgwick Street, Dept. E Chicago 10, Illinois, U. S. A.

Manufacturers of Scientific Instruments and Laboratory Apparatus

358

k d

0

SCIENCE, VOL. 122