Peptidesynthesis:If you want to do it, we'll help you.If you want to avoid it, we'll help you.

-E. .,

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Peptide SynthesizerThe Schwarz BioResearch Automated Peptide Synthesizer isthe first commercially-available peptide synthesizer. Under li-cense from the Danish Institute of Protein Chemistry, the syn-thesizer makes use of Merrifield's solid-phase chemistry. Theheart of the unit is an automated control unit which dictatesthe sequence, volumes, and mixing times for reagents andsolvents per the program determined by the operator. And be-cause the instrument can be programmed to run for a full24-hour day, the time required for peptide synthesis can nowbe significantly shortened. Please use the coupon to get details.

Peptide "Starters"We supply virtually every starting material needed for peptidesynthesis, 33 Boc-amino acids. 22 '4C and 3H-labeled Boc-amino acids. 12 Boc-amino acid resin esters. Chloromethy-lated resin. DCC. And dozens upon dozens of unlabeled and14C, 3H, 5N, and 35S-labeled amino acids, derivatives, and re-lated compounds. Please complete the coupon below for de-tailed listings, specifications, and prices.

Available PeptidesWe now can supply the following biologically active, chemicallypure (> 95%) synthetic peptides: [Asp', lIe5] Angiotensin Iand II, Bradykinin, Lysyl bradykinin, Methionyl lysyl bradykinin,Tetradecapeptide renin substrate.

And these '4C-labeled peptides are also available:[Leul0-14C (UL)] [Asp', lIe5] Angiotensin I[Ile5-14C (UL)] [Asp', lie5] Angiotensin II[Pro2-14C (UL)] Bradykinin[Pro3-14C (UL)] Lysyl bradykinin[Pro4_14C (UL)] Methionyl lysyl bradykinin

r [Val3-14C (UL) ] Tetradecapeptide renin substrate.Please use the coupon for details:

Peptide Custom SynthesisAs is evident from this page, our commitment to peptide syn-thesis is rather substantial. And supporting the endeavors de-scribed here is an unusually competent and innovative groupof synthetic organic chemists. This puts us in the position tosuggest that you query us about custom synthesis of peptidesyou'd like to have. Drop us a line, or give us a call at 914-359-2700, or use the coupon for further information.

CPK Atomic ModelsThese inexpensive, space-filling models are most useful for thestudy of structure, function, and synthesis of polypeptides.Schwarz supplies CPK Atomic Models, kits, or pre-constructedamino acids. Write for details by using the coupon.

| Schwarz BioResearch 1Division of Becton, Dickinson and CompanyOrangeburg, N.Y. 10962

Please send data on: I

Peptide Synthesizer. CCustom Synthesis. lrPeptide "Starters." Ea CPK Atomic Models. |Available Peptides. |

Name

Dept.

X Institution

l Address

cCity State ZipL----- --- --------------------J

Schwarz BioResearchDivision of Becton, Dickinson and CompanyFBBD ;

Orangeburg, N.Y. 10962

Circle No. 10 on Readers' Service Card

*:t

17 OCTOBER 196'3 309

TILelectrocexperiment.

Chances are thePAR Model1e70can perform it.

rur examrpte, it aitows you to perro-rchronoamperometry without requiringIt also contains built-in controls for cur;threshold. What's more, the 170's 100pliance and its 1 amp capability at thi.volts) mean that you can work in the miThe 170 can also perform:* phase-sensitive ac * direpolarography * coIn

* pulse polarography elec* dc polarography u con* anodic stripping analysis * chrc* cyclic voltammetry * chr(* pH and specific ion * pulsmeasurement

The Model 170 contains a built-in X-Y pvoltage curve recording as well as aintegrator and an accurate time-base geequipment occasionally required is an c

The price? With rmechanical drop tirn$11,500. For more information, writeCorporation, Box 565, Princeton, N. J

For those applications requiring a less cccapability to perform dc, ac and p'u1seabout the Model 171 Polarographic A

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inquire,corder.

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AMON-A

Polyacrylamide gel allows a range ofpore size for optimum sieving of your sampkl.That's because it forms a useful gel over awier concentration range than starch. Youiean also create two-dimensional variations o.fpore size for further molecular size Mifortmation.

Polyacrylamide gel achieves superiorresolution. Partly, that's because there areno ionized groups, therefore no electro4osmosis. Thus, the site of application is atthe true zero of the mobility scale.

Polyacrylamide gel has a clear, color-less background after destainig. Since therew:is no intermediate slicing and clearing aswith starch gel, there are fewer errors intransmission densitometry.

Polyacrylamide gel is strong and long-lasting. Wrap it in Saran Wrap; you cankeep it for years,

Circle No. 93 on Readers' Service Card

312

It is not surprising that there maybe more sagebrush in some situLationsafter spraying. The control programsare not intended to kill all the sage-brush anid its recovery and, indeed, itsspread will depend muLch on subsequentrange nm;lanagement. I douLbt that theincrease in sagebrush can be attributedto the spray program.

KEITH C. BARRONSDowt Chemical Compa1.v,Post Office Box 1706.Midlal(I. Michia,n 48640

References

1. G. E. ILvvn and K. C. Batrroils. Poroc. North-east. Weed Control Cooif. (Rutgers Univ.. NcwIBli-nswick. N.J.. 1952). p. 331.

2. J. NI. Stund and NI. J. Wi-ight, Down1 to Earth(Dow Chemical Co., Midland, Mich.. stiltm-inier, 1959).

Less Materialism-i'More Tradition

Abelson's editorial "Microcosms in aworld apart" (29 Aug., p. 853) statesthat "we are not getting our money'sworth, and it is time that construLctivethought and effort were devoted to mak-ing it possible for the majority of ourcitizens to enjoy what couLld be achievedin the way of spirit-building recreationalfacilities." Such a goal could be achievedin the next generation if we, the pres-ent generation, became less materialisticand acquired the Old World's venera-tion for and teaching of tradition-quite opposite to our habits of permis-siveness.

I was born and brought 'up justaround the corner from Frankfurt'sPalmengarten and I appreciated Abel-son's comments on its skilled landscap-ing anid grassy glades. However. I alsorecall how sad I was when all thatbeauty disappeared temiporarily duringWorld War I to make room for grow-ing potatoes!

STEFAN ANSIIACHERPost Office Box 867,M4arioni, Intiliana( 46952

Botanical Congress

The U.S. National Committee of theXIth International Botanical Congress,held at Seattle, Washington, frcom 24August to 2 September. passed the fol-lowing two resolutions which should beof interest to readers of Science:

In spite of the progress N% hich has beenmade in maintaining food resources tokeep up with the "s orld's increasing popu-lation, the members of the XI Interna-

I

TheUniversalHumidityTransducer

. still eludes us. Foryears we searched for ahumidity transducer asversatile as the thermistortemperature transducer.No luck! So we've designednew "state-of-the-art"into instruments for allthree classical humiditymeasurement methods:

wet bulbdepressionheateddew pointrefrigerateddew pointYSI's advanced thermistortechnology is used tomaximuml advantage,helping in each of thesemethods to minimize thegreatest source of error-the temiiperature sensingelement and its readout.

Let us send you completespecifications. And shouldwe succeed with theuniversal humiditytransducer, we'll senddata on that, too!

Circle No. 83 on Readers' Service Card

SCIENCE, VOL. 166

I

tionial l30ta1nic.al CoIiCr C5ss consciOLs oftliei r responsibility ,Is hiologists, considerthat there is no solItion to the final prob-lem uiniless populaktion contirol is achieved.1 herefore. we uIreC governments to aIdoptstuich policies xhilue at the same time en-sill inT an adeqUate standard of liv ing fortlhlie people, parltiCularly by enCOUragingiucreased food prodCtLCtion commenIsuLratex\ith proper laund uise.The Xlth International Bot;anical Con-

°i Cess, reCCOCInizinge the imiportince of pre-sci otu exery aspct of the di\ ersitv andi-esoui ces of the elirth's biosphere. eqticeststhil -ovcrnments of the couintr-ies of the,orl the inter-goverrniental organizationsof tihc Unit0d Nations family. particulaIrlythose iwn,olved in technical lassistance proj-ccts intenidedI to promote scienitific, cLIl-tir.al and economilic developiment. otherintet cox ernnmental and non-goxernmnintalor.alili/ations involved in conservlationmatutel-s, Universities aInd1 other institutionsol leirning and research, land any othergrotup or inlividlCIL interested in conserva-tion. to dlo all in their power to encouragee\xcrv elTort to preser\e the earith's bio-sphere fromii the mainifold dlestrCtive in-flienc,s of Man. including the release ofpcisistenlt toxic materials. We tirge suLpportof the consers ation pi ojects embiobdicd inthe Internaltional Biological Program andx ithin the ambit of the InternationalCouIncil of Scientific Unions and Interna-tional Union for Conserv.ation of Natureand NatuLral Resoturces.

HlERBERT G. BAKERBot(aznicail Gar(len)U'niverssity of California, Berkeley 94720

Astronaitits Resignation

The news note "TrouLble at NASA:Space scientists resign" (22 Aug., p.776) refers to a comment made byNASA officials that I resigned fromthe scienltist-astronaLlt program becauseI didn't want to beconie a pilot.

This is an oversimiiplification. ThebuLdgetary delays in plans for scientificspace flights and the inability to carryotn a reasonable amouLnt of scientificresearch in the meantime were equallyimportant reasons. I discussed all thesereiasons in the statemenit of resignationwhich I submitted to NASA for publicrclease. ' Flying just isn't my cup oftea" was quoted in the NASA oflicialannollolncement from a telephone con-versation with Deke Slavton and noteven included in my statement.

This is one of those uinfortulniatecases in which news is distorted be-cauise only a small portion is taken outof context for simplicity and read-ability . . . I

BRIAN O'LEARYDepartment of A stronomy antd SpaceSceiences, Corniell UniiverNitY,Ithlaca, Newv Yot-k 71.850

PERKIN-ELMER DOUBLE-BEAM GRATING SPECTROPHOTOMETER

This instrumneint is the only one in its class offerinlg miieter readout that's liinearin both trainsimittance and absorbanice. It proxvides fully automilatic ratio-re-cording; gix es you the calpabilities of b)oth aldouble-beami automiiatic andl asingle-beamil mianual spectrophotomn-eter; anid. Iiov that eight Iliajo-aocessoriesare available, Model 1241 is even more xversatile thlain before.

You cani learn to operate the "124" in. ininutes. There .are fl() logarithmicscales to interpolate, IIo time-consuming p)rocedures, Slit selectioni is simlle.(There are three fixed specttal b)andl wx idIths: 0.5, 1.0, or 2.0 mp. And filterchanges are automatic. Sample anid reference are compared automiiatically,and the linear absorbance or transmiiittanice ratio is lpresente(l (lirectly to themeter or recorder. Besides, you can accomplish three times mlore wvork coin-parecl vith instruments of older design ... b)ecause the "121" operates atfoui scanning speeds (up to 240 m1/ per miniute), and scans the enltire visil)lerange in less thani twvo miinlutes! Overall range is 190 to 8000 mn,t.

With Model 124, you can xxvork wvith 1)oth hiigh and( extremely lowv conicen-trationis . - thlanks to the large cell compartment wshich accomllillodates cellsxvith light path lengths up to 100 Inmmn long. In addition, you can ol)tain read-ings in 0 to 2.0 absorbanee, ot expand x-our readings wvith the 0 to 1.0absorbance range.

Solid state circuitry in Model 124. results in exceptional zero-A liinestability and superb performance. Ask us to send you Bulletin B-312B.

Branches. BostonMass.

LABRATO1~RY...:L A';Ffff f -RY0000: fi* APPARATUS* INSTRUMENTS

GLASSWAR70-Danbury Elk Grove Village Fullerton PhiladelphiaConn. Ill. Calif. Penna.

Circle No. 37 on Reoders' Service Card

Silver Spring Syracuse'Md. N.Y.

17 OCTOBER 1969

7.i.S I,

313

The 4xSI'abcamera that has a mind

-mOt II own~v,l

It gives youperfect exposures.

Automatically.From cat jaw to concrete, from spleen to

diatoms. whlatever you photograph in your labthe new mnodel Leitz ARISTOPHOT bellows

camera with automatic exposure control takesthe guesswork out of it.

This exposure system is fully transistorized,with a photomultiplier detector, and practicallyunlimited exposure range. You get exactexposure control independent of bellowsextension, eyepieces and methods ofillumination. Exposure control is individuallyadjustable to the characteristics of each

specimen. Arid can also be set m-anually.The ARISTOPHOT is extremely versatile.

It can be used bothn with a microscope and amacroscopic setup. The film speed ranige is6 ASA to 10.700 ASA. The built-in vibrationdamper on the shutter gives you perfectpicture sharpness at all magnifications andshutter speeds.

Write for complete details andspecifications to:sEec

E. Leitz lInc.. 468 Park AveiiLie South, N.Y., N.Y. 10016

hallmarkPHOTO RECORDERSNewest and simplest to operate! Easier, faster, more accurate recording!Exclusive time-saving features eliminate many steps required by conventional light beam recorders!

* Writing speeds greater than 80,000 inches per second* Built-in galvanometer sensitivity control and impedance matching network for each channel* Wide selection of high quality, low cost galvanometers - $35 to $70 each* Plug-in galvanometers - no adjustments!* No dummy galvanometers - no special tools!* Individual signal input switch to check spot zero* Simultaneous overlapping data recording on all charinels* Automatic synchronous timing lines and chart speeds AS P* Grid line system printed simultaneously with signal* Long optical arm for greater linearity -173/4* Fingertip push-button channel selection system* Individually fused galvanometers (optional)* Wide range of speeds -12 steps* Provision for remote operation* Infinite resolution trace intensity adjustment* Frequency response exceeding 10,000 Hz* Simple push-button operation* Paper supply indicator 4* Portable or rack mount

'ORTABLV AS A 6 PACKThe rugged modular construction of the

Hallmark light beam oscillographsprovide maximum flexibility in

the field or laboratory.Modular design enables allcomponents to be removed

5 and replaced easily.

THE 6 PACK(1) Power pack, (2) Rear input

and impedance network,(3) Control panel, (4) Drivemotor and transmission,

(5) Temperature compensatedmagnetic block.

(6) Chassis -stress relievedand rigidly reinforced

cast aluminum.See us at ISA! -WSee us at NEREM!See us in your ownbackyard! Call for -the Hallmark Mobile H D SYSTE S 25WaDivisi onof Hallma rkStandards,Inc.Instrument Van! HALLMARK DATA SYSTEMS 257 Washington Street, Mt. Vernon, N. Y. 10551 (914) 664-4288316 Circle No. 1 on Reocders' Service Card SC IENCE. VOL. 166

Type 29011 through 6

channels

@1969 EAM INSTRUMENT CO., INC.

TheonlySthingwe 'ont sell.

In other words, E & M is anelectronics firm, not a vivarium.We design and produce the mostcomplete electronic recordingsystem made for life scienceteaching.

Every part of our Physiographsystem is produced under our de-sign and control.So you can be sure of its

performance.Our system features total reli-

ability and absolute simplicity ofoperation.

So your students can concen-trate on their experiments, andnot on the equipment they use intheir experiments.Which is how it should be.We offer four recorder models.Our Physiograph Six accepts

up to six channels, our Physio-graph Four "A", Projector Physio-graph, and Desk Model Physio-graph accept up to four channels.An additional servo channel can

be installed on any model.And all of our Transducers, Pre-

amplifiers, Accessory Plug-InModules, Biotelemetry Systems,and Accessories are completelyinterchangeable and compatiblewith any Physiograph.

Including the very first one wemade, over ten years ago.

If you'd like information aboutour systems, or have questionsabout the availability of specialapplication accessory items, callus. Collect.

Or drop us a line, and we'llarrange a demonstration.

Et4 1. PHYSIOGRAPH SIX MAIN

-W 2 DESK MODEL PHYSIOGRAPH

w w 23 PROJECTOR PHYSIOGRAPHn -E& M INSTRUMENT CO., INC. II NSTRUMENTATION FOR RESEARCH AND EDUCATION / 7651 AIRPORT BLVD. P.O. BOX 12511 / HOUSTONTEXAS 77017, AC 713 644-7521. CABLE FISIO