Now in bead form forchromatography ofbiologic substances...

S>ephladexIon ExchangersBecause of its advantages-sta-bility and inertness-Sephadexhas been used to produce a newclass of ion exchangers: QAE-,DEAE-, CM- and SE-Sephadex.Since their introduction they havebeen used extensively, particu-larly in the biochemical and clin-ical field.In the new bead form they will bemore useful both for laboratoryand manufacturing scale proc-esses. Their spherical shapegives increased mechanicalstrength and leads to easiercolumn packing. More uniformparticles result in improved

U1F hydrodynamic properties.All Sephadex Ion Exchangers have a highcapacity and low nonspecific adsorption.They are available in two types that differin porosity, thus offering flexibility for yourspecific requirements. Sephadex Ion Ex-changers are of analytic grade purity andare produced under rigorous quality con-trol, thus ensuring uniform products togive accurate and reproducible results.J.o g/ml Fu6P2%T 25 37A100 Hexose mono phosphates Fru-1,6-P2A0 100 P20 0 jAT

600glycogenglucose 1 1

Model experiment with glycogen, glucose,sugar phosphates and adenosine phosphateson a column of DEAE-Sephadex A-25.(From Biochim. Biophys. Acta 74 (1963) 588, by permissionof the author)

Anion ExchangersType Grade Ionic Capacity Bed Volume'

Form (meq/g) (mu/g)

QAE.Sephadex A-25 40-120u Cla 3.0 + 0.4 6040

Sephadex A-s5 40-120ja Cla 3.5 ± 0.5 3-40

Sephadex A-50 140-1 20.u ICl 3.5 :+- 0.5 25-33Cation Exchangers

Type Grade Ionic Capacity Bed VolumezC-r Form (meq/g) (ml/g)

SE.Sephadex C-25 40-120jg Na* 4.5 + 0.53 10

Sephadex C-50 40-120ju Na* 4.5:!: 0.5 32-40

SE-Sepade C-2 40120/1 Na* 2.3 -+ 0.3 5-9

Sephadex C-so 140-120,g Na' 2.3 ±_ 0.3 30-301. In Tris-HCI buffer. pH =8.3. ionic strength=0.05.2. In sodium phosphate buffer pH = 6. ionic strength= 0.06.For additional technical information, includingbooklet on Sephadex Ion Exchangers, write to:

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Circle No. 82 on Readers' Service Card

which Carter reports was singularly un-fortunate-a reaction to disapproval ofa particular road project in the Sena-tor's state rather than a well-consideredcontribution to the public debate onpark policy. Our legislators, too, mustlearn to evaluate park programs onqualitative grounds-admittedly a moredifficult matter than relying on travelstatistics and road mileage. Moss titledhis speech "Parks Are for People," atoo oft-quoted trite phrase which F.Fraser Darling and Noel D. Eichhorn(in a major study of park policy for theConservation Foundation) dismiss as"inappropriate huckstering.". . .

DOUGLAS W. SCOTTDepartment of Forestry,University of Michigan,Ann Arbor 48104

Ballast Overboard!

Our report about the transportationof European Cretaceous flint to NorthAmerica largely in the form of shipballast (1) prompted several readers toreport additional localities. The vicinityof New York City appears to have beena favorite dumping area for ship bal-last, in view of its history as a greatseaport. An article by Rose (2) de-scribed flint pseudoartifacts on Glen Is-land in Long Island Sound near NewRochelle, and traces the derivationof other kinds of ballast found inthe New York area. I. G. Sohn(U.S. Geological Survey, Washington,D.C.) reported collecting flint nodulesin the Bronx at Hunts Point in theearly 1930's. W. S. Newman (QueensCollege) mentioned European Creta-ceous flint in landfill of FlushingMeadows. E. A. Weiss (Sun OilCo., Philadelphia) reported heaps oflarge flints on the tidal flats of theHackensack River south of Bayonneand Jersey City. H. G. Richards (Acad-emy of Natural Sciences of Philadel-phia) described flint with West Indiancoral near Woodbury, N.J., south ofCamden. W. A. Price (Corpus Christi,Tex.) told of having been tested by hisgeology professor with Dover flint intrack ballast of the Northern CentralRailroad near Baltimore, Md. C. G. Hol-land (Charlottesville, Va.) sent speci-mens of European Cretaceous flint thathe had found on the beach of the Mat-taponi River near Newington, Va., andone nodule from Tar Bay about 10miles down the James River fromHopewell, Va. Frederick Johnson (R. S.

Precision molded and precisioncalibrated, the Nalgene' Volu-metric Flask is in a class by itself.It won't etch, contaminate orbreak. Repeated autoclavingwon't affect its accuracy. Eachflask is individually calibrated tobetter than ±3X of 101%.100 ml size now in stock, 250,

500, and 1000 ml sizes comingsoon. Order from your lab supplydealer. . . and specify NalgeneLabware. Ask for our 1968 Cata-log or write Dept. 2122, NalgeneLabware Division, Rochester, N.Y.14602.

NALGERITTER PFAUDLER CORPORATION

Circle No. 89 on Readers' Service Card

Peabody FouLndation, Andover, Mass.)described flint ballast stones at Straw-berry Bank in Portsmouth, N.H., andthe presence of small chips in thelower levels of the recently excavatedFort Constitution in Portsmouth harborthat are suLggestive of local manuL-facture of gunflints. Lastly, V. K.Prest (Geological SLirvey of Canada,Ottawa) reported the presence of Eng-lish flint at an old sailing-ship portnear the southeastern end of PrinceEdward Island, Canada.

Although the quantity of EuropeanCretaceous flint brought to NorthAmerica as ship ballast can never beknown, it must easily exceed 100,000tons, considering the large number ofships that carried it as ballast and thevery large number of known points ofdischarge.

K. 0. EMERYWoods Hole Oceanographlic Institution,Woods Hole, Massachusetts 02543

References

1. K. 0. Emery, C. A. Kay. D. H. Loring,D. J. G. Nota. Science 160, 1225 (1968).

2. F. P. Rose, A mecr. A ntiqulitY 33. 24() (1968).

Scotindrelly Fellow

The allusion to "The groves of aca-deme" in Nelson's excellent article("University of Hawaii," 16 Aug., p.673), is apposite, but is inaccurate insome respects. The character (HenryMulcahy) in the novel is not an "out-spoken professor," but a "self-pitying,"incompetent, and lazy instructor in liter-ature. Confronted with a letter termi-nating his appointment, he decides tofabricate a story that he had long beena member of the Communist Party. Thisfalsehood he exploits successfully as aform of job insurance by leaking the lieto sympathetic fellow faculty members.They rally vigorously to the cause ofacademic freedom and, without at-tempting to get the facts, they fightfor the right of Henry to be a Com-munist. Mulcahy's cause snowballs ashe invents more lies, and as more in-tellectuals join the battle against theforces of reaction.Mary McCarthy. as a novelist, is, of

course, entitled to poetic license increating a fictional situation which isremote from reality. Any resemblanceto persons living or dead is purelycoincidental.

THOMAS H. JUKESSpace Sciences Laboratory,Uniiversity of Califoirnia, Berkeley 94720

With this steady flow HDLTER pumpyou handle

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Precision molded silicone elastomer pumping chambers elimin-ate the hysteresis effects that make PVC and polyethylene un-desirable in precision work. Useful life of the chambers is wellover 2,000 hours. Provided in two internal diameters, they areautoclavable and easily interchangeable. Because the chambers arecompletely occluded by the head rollers, the RL175 does not"dribble" when shut off. You stop and start with identical, virtuallynon-pulsatile flows.The circuitry and mechanical safety features of the RL175 suit it

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Circle No. 27 on Readers' Service Card18 OCTOBER 1968 39

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Y d of view

You get up to 21/2 times more image area with a Leitz ORTHOPLANmicroscope than with conventional wide-field microscopes.Thanks to the Piano objectives pioneered by Leitz, you get maximuminformation over an expanded field of view... see more withouthaving to change the field.The ORTHOPLAN gives you unlimited research capabilities, sincea full line of interchangeable optical units and accessories are avail- dOPP"able for it. You can use all forms of transmitted or reflected illumina-tion with the ORTHOPLAN.For more information on ORTHOPLAN, the finest research micro-scope in the world, write to Leitz. 69a9 6 -

E. Leitz,Inc.,468 Park Avenue So.,New York, N.Y. 10016Circle No. 11 on Readers' Service Card

310 SCIENCE. VOL. 162

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