Iodine Content of Some Marine Algae1

MADELON R. GRIMM2

THE LITERATURE ON IODINE and iodide con­tent of marine algae has been reviewed byFritsch (1945), Chapman (1950), and Smith(1951) . To their extensive bibliographies, thecontributions of Turrentine (1912) and Cam­eron (1914, 1915) may be added.

Since man y of the early investigators wereinterested primarily in the economic aspectsof the algae, they generally disregarded thesuitability of the species studied for labor­atory use. For example, their interests wereconcerned with the extraction and ut ilizationof iod ine for dietary and medicinal purposes.The use of this substarice in fertilizer re­sources was also promoted.

In recent years the use of iodine in tracer .studies with its many applications necessi­tates an expanded spectrum of availablespecies 'of algae to determine which organ­isms lend themselves to further laboratorystudy in this field. As far as can be determined,very little work has been done to ascertainthe manner in which algae are able to ac­cumulate iodine and retain it against enor­mous concentration gradients. In search ofsuitable experimental organisms for such stud ­ies and unde r the assump tion that such

1 Based in part up on data included in a th esissubmitted to Cornell Uni versity in partial ful fillmentof the requir ements for the degree of Master of Science.Th is investigatio n was performe d under the supe r­vision of Dr . .M axwell S. D ory and D r. Walter C.Muenscher and supported in part by grants fromCornell University and Graduate Research Fun ds ofNorthwestern Un iversity. Manuscript received Febru-ary 20, 1952. .

2 Research D epartment, Di vision of Microbio logy,Ciba Pharmaceut ical Products, In c., Summit, Ne wJersey.

organisms should both accumulate iodine andlend themselves to modified microbiologicalprocedures, numerous species of marine algaewere examined . .

The samples studied were collected alivein the field and air dried in the laboratoriesof the collectors (see footnotes of Table 1).Upon receipt, these collections were cleanedand redried at room temperature. A weighedamount (usually 1 gm.) was incinerated to ablack ash in a porcelain crucible over a Bunsenburner. The .ash was pulverized and mixedwith 5 milliliters of distilled water and thesoluble portion separated by centrifugation .The supernatant was shaken up with 1 milli­liter chloroform, 2 milliliters hydrogen per­oxide, and 1 milliliter glacial acetic acid.After several minutes, the presence of iodinewas manifested by a pink to pur ple color inthe chloroform layer, the intensity of thecolor increasing with iodine concentration.When the nonchloroform layer retained abrownish tinge, more hydrogen peroxide andacetic acid were added until decolorizationoccurred, and the mixture was reshaken. Thecolor of the chloroform layer was comparedto color standards containing kno wn concen­trations of iodine in chloroform . This methodis assumed to be a satisfactory means ofestimating the iod ide content of the algalash when iodide is present in concentrationsof over 30 parts per million.

Quant itative estimations for iodine ob ­tained in this investigation are presented inTab le 1 and are expressed in milligrams pergram of dry weight of alga and in parts permillion . Unused portions of the collections

[318 }

Iodine Content of Algae - GRIMM

TABLE 1IODINE CONTENT OF VARIOUS SPECIES OF ALGAE

319

MG. 12/ PARTS PERSPECIES TESTED COLLECTION* SOURCEt GM. ALGA MILLION

ChlorophytaA nadyomenestellate (Wulf.) C. Ag . . . . . . . . .. . ... B 49-2134 B 0.156 160Avrainvillea longicaulis (K uetz.) M urray & Boodle . B . . . . B 0.024 20Bryopsis plumosa (Hu dson) C. Ag . . .. . . 0 0 • 0 • 0 • •• G . . . . M 0.195 200

. Chaetomorpha linum (M ueller) Kuetz. 0 0 0 0 0 0 0 ••• 0 G .. . . M 0 0B 49-2203 B 0.110 100

Codium tntertextum Collins & Hervey 0 0 0 ••• 0 •• 0 • 0 B 49- 2139 B 0.300 300Codiumsetcbellii Gardne r . . ... . 0 •• • • • 0 • 0 • •• 0 • • 0 H . .. . 0 0.078 80Dictyospbaeria cavernosa (F¢rsk.) Boergesen . . . . . 0 • D 8118 H 0 0.. D 8584 H 0.039 40Halimeda monile (Ellis & Solander) Lamour. ... 0 • • B 49- 2103 B 0.02 20VIva expansa (Setch.) Serch. & Gard. . . . . . . ..... H 1054 0 0.059 60

PhaeophytaA garum cribrosum (Mertens) Bory . . 0 • • 0 • • • • •• • • G 249 M 0.078 80Alaria marginata Post. & Rupr.. . 0 0 • • 0 0 • 0 0 0 0 • 0 0 H '" . 0 0.059 60Ascophyllum nodosum (1.) Le ] olis . .... . . . .. . . . .. G . . . . M 0.156 160Asperococcus ecbinatus (M ertens) Gre v. . . 0 0 0 0 • 0 . 0 0 G 258 M 0.056 60Chorda filum (1.) Lamour. . .. .. . . . 0 • • • • • • • • • • • • G ... . M 0.227 230Chordaria j/agellijormis (M ueller) C. Ag . 0 •••• • 0 • 0 G 283 M 0.313 310Cladostepbns verticil/atus (Light.) C. Ag . . 0 • 0 • •• • • • G 277 M 1.094 1090Coilodesme bul/igera Stroemfelt. . . . . . . . . . . . 0 ••••• H 1019 0 0.234 230Coilodesme californica (Rupr.) Kjellm. 0 ••• 0 • • 0 • • • • H 1074, 1075 0 0.25 250Cystoseira osmundacea (M enzies) C. Ag o0 • 0 • • 0 0 • 0 • H . . . . 0 0.117 120Desmarestia aculeata (1.) Lam our. 0 • • 0 • • 0 0 • 0 • • • • • G 287 M 2.5 2500Desmaresti« munda Serch. & Gard. 0 • • • • • 0 •• • • • • • H 7689 0 0.469 470Dictyopteris plagiogramma (Mont.) Vickers .... 0 •• B 49-2081 B 0.234 230

D 8561 H 0.02 20Dictyosipbon foeniculaceus (Hudson) Grev. : ... . . .. G . . o . M 0.284 280Dictyota dichotoma (Hudson) Lamou r. . . .. .. . .. . . B 49-2206 B 0.013 10Ectocarpus siliculosas (Dillwyn) Lyngbye . . 0 0 • • 0 •• • G . . o . M 0.087 90Elachistea jucicola (Velley) Aresch.... 0 • • • • • • • ••• G . . . . M 0.195 200Fucus evanescens C. Ag... . .. . . . . 0 • 0 0 • 0 • 0 0 0 0 • ••• G 278 M 0 0

H 1088 0 0.078 80Fucus evanescens f. oregonensis Gard . . . . 0 0 0 0 • • 0 0 0 0 • H 1077 0 0.078 80Facas furcat«: C. Ag. . . . . 0 0 0 •• 0 • • • • • 0 •• • • • •• • • H 1078 0 0.117 120Fucus spiralis 1. . . ... . ...... ... . ... ... 0 ••• 0 0 0 0 G . . , . M 0.120 120Fucas uesiculosus 1. . . . . .. . ... . .. .. . . . . . . .. . . . . G . . o . M 0.052 50Haplogloia andersonii (Farlow) Levring 0 0 ••• 0 • • 0 • • H 1064 0 1.25 1250Hedophyl/um sessile (c. Ag.) Setch.. . . . . . . . . . . . . . H . . . . 0 1.25 1250

. Laminaria agardhii K jellm .. . . . . . . ... . . . 0 • 0 • • 0 • G 268 MYoung th allus .. . 0 0 0 • • • 0 ••• • •••• 0 0 0 0 • • • 0 0 0 • 3.125 3130Blade . 0 • • •• 0 0 .0 0 •• 0 . 00 •• 0 . ... . . . . . . .. .. . . 2.083 2080Stipe... . 0 • • • • •• •• • ••• • • • • 0 0 • 0 • • 0 0 0 0 .0 0. 00 1.563 1560H aptera and rhizoids . 0 , • 0 • • 0 0 ••• • • • •• • • • • • • 5.0 5000

Laminaria andersonii Eato n in Hervey . 0 0 •• 0 •• • • 0 H . . .. 0Blades . . . . . .. .. . 0 ••• • • ••• 0 0 0 0 0 0 0 0 0 0 • • o. . . 0.938 940Up per stipe .. .. 0 • 0 • • • • • • • • • • • • •• • • 0 • •• o. 0 • 5.0 5000

Laminaria digitata (1.) Edm. . . . . . . 0 •• 0 0 • 0 •• 0 •• G 279 M 1.041 1040Laminaria saccharina (1.) Lamour.. . .. . . . . . .. . . . H 1065 0

Lower blades 0 • ••• ••• • •• 0 0 • • 0 •• 0 • • 0 0 0 0 •• • •• 1.25 1250Laminaria sinclairii (Aresch.) Anderson 0 • • • • 0 • 0 • H 1058 0

Blades . . . 0 . 0 0 ••• • 0 . 0 .0 .0 0 •• 0 0 •• 0 • 0 0 • 0 • • 0 • 5.0 5000Hapte ra and rhizoids . . . 0 0 • 0 0 0 0 0 •• 0 0 0 0 • • 0 .0 • 1.875 1880Stipe . . . . . . . . ... . . . . . . . . . . 0 • •• • • 0 0 • ••• 0 • • • 3.75 3750

Lessoniopsis littoralis (Tilden) Reinke . . 0 •• ••• 0 •• • • H .. .. 0 0.117 120M acrocystis integrifolia Bory . . . . . . . . . . . . . . . ... . . H . . . . 0

Blades . . . . . . , ... .. 0 •• 0 • • 0 • • 0 • • • • • • 0 • 0 • •• • 0.938 940Axis of branch . . . . . 0 • • 0 • • • • • • • •• • • 0 •• • • • 0 • 0.117 120

320 PACIFIC SCIENCE, Vol. VI, October, 1952

TABLE 1-continued

SPECIES TE STED

Meso gloia divaricata (c. Ag.) Kuetz .Nereocystis luetkeana (Mertens) Post. & Rupr .

Air bladder .Sterile blades .

Peluetiopsis limitata (Setch. ) Gard .Postelsia palmaeformis Rupr. .

Blades .Stipe .Ho ldfast. .

Pterygopbora californica Rupr .Ralfsia clavata (Carm .) Croua n .Sargassum sp .Sargassum filipendula C. Ag. . . . . . . . . . . .Sargassum kjellmanianum Yendo .Sargassum natans (1.) ] . Meyen .Sargassum obtusifolium] . Ag .Scytosipbon bullosus Saunders .Soranthera ulvoidea Pos t. & Rupr. .Sphacelaria cirrhosa (Ro th) C. Ag. . . . .Turbinaria tricostata Barton .

Rh od ophytaAhnfeltia concinna J. Ag .Ahn/eltia plicata (Hudson) Fries. . . . .. . .Amphiroa/ragilissima (1.) Lamour. .

Coarse type .Fine type .

Antithamnionuncinatum Gard .Asparagopsis hami/era (Har iot) Okamura .Asparagopsis sanfordiana Harvey .Laurencia spectabilis Post. & Ru pr. . . . . . . . . . .Lophocladia trichoclados (Mer tens) Schmitz .

Asparagopsis taxi/ormis (Deli le) Collins & H ervey .Bostrychia scorpioidesvar. montagnei (Harvey) Post. .Botryglossum /arlowianum (J. Ag.) D e Toni .Callithamnion baileyi Harvey , .Callithamnion pikeanum Harvey .Centroceras clavulatum (c. Ag.) M ont. .Ceramium eatonianum (Farlow) De Ton i .Corallina officinalis 1. .Cryptopleura brevis Gard .Cryptosipboni« woodii J. Ag .Cystoclonium purpureum (Hudson) Batt ers .Cystoclonium perpureum var. cirrhosum Ha rvey .Galaxaura obtusata (Ellis & Solander) Larnour .Galaxaura squalida Kje llm .Gelidium arborescens Gard .Gelidium corneum (H udson) Lamour. .Gelidium coulteri Harvey .Gelidium crinale (Turner) Larnour .Laurencia obtusa (Hudson) Lamour .

Gree n phas e .Yellow phase .

Microcladia borealis R upr. .Odonthalia fioccosa (Esper) Falken .Odonthalia washingtoniensis Kylin .Pbycodrys rubens (Hu dso n) Batters .Pbyllopbor« membranifolia(Good. & Woodw.)J.Ag.Plocamium pacificum Kylin .

COLLECTION *

G .H .

H ... .H

H .G .D 8572G . . . .H 1067B 49-2067D 8114H 1238H 1074G . . . .B 49-2231

H 1233H 1219B ... .

H 1145G 286D 8663H 1107B 50-426B 49-2086B 50-5 16B 50- 382H .. . .G 203H . . . .B 49 -2 151H .G .H 7680H 768 5G 204, 270G . . ..B 49-2 144B 49-2070H 1030D 8709H 1031, 768 7G .. ..

B 49-2195B 49-2194H 1130H 1133H 1114G 285G .. ..H 1191

SOURCEt

Mo

oo

oMHMoBHooMB

ooB

oMHoBBBBoMoBoMooMMBBoHoM

BBoooMMo

MG . 12/GM . ALGA

0.240

0.9380.6250.156

1.250.4691.250.0290.0870.0 20.1560.020.0590.0290.0200.2340.3140.029

0.020.117

0.0290.1560.020.9381.250.Q780.1170.1171.8750.010.3130.2340.0390.2340.0390.020.0290.117trace

0.0390.1170.0590.0390.0290.1170.11 7

0.0390.1 170.020.Q780.4070.313trace0.029

PARTS PER

MILLION

240

940630160

1250470

1250309020

16020603020

230310

30

20120

30160

20940

125080

120120

187510

310230

40230

402030

120

40120

604030

120120

40120

2080

420310

trace30

Iodine Content of Algae - GRIMM

TABLE I-continued

321

MG. I.! PARTS PER

SPECIES T EST ED COLLECTION * SOURCEt GM . ALGA MILLION

Plumaria filicina (Farlow) Kuntz .. ...... . . . . ... H 7681 0 1.25 1250Plumaria bypnoides (H arvey) K untz . .. . . .. .. . . . . H 1236 0 0.078 80Plumaria sericea (Harvey) Ru pr , . ........ .... . .. G . . o. M 0.32 320Polyides rotundus (GmeIin) Grev . . . . . . . . . . . . ... . G . . o. M 0.039 40Polyneura latissima (Ha rvey) K ylin . . . . . . ... . . .. . H 1147 0 0.039 40Polysipbonia elongata (H udson) Harvey . ... . . . . . . G • . o. M trace tracePolysipbonia lanosa (1.) Tandy... . . . . . .. .. . . . . . . G . . o. M 0.438 440Porpbyra naiadum Anderson .. . . . . . .. . . .. . .. . . . H 1023 0 0.313 310Pterocbondria woodii (Harvey) Hollenberg .. .. . ... H 1148 . 0 0.078 80Pterosiphonia biplnnata val. robnsta (G ard.) Dory .. H 1213 0 0.078 80Rhodomela larix (T urner) C. Ag. .. . . . . . . . . . . . . . . H 1033 0 0.156 160Rhodymenia californica Ky lin . . . . . . . .. . . . .. . . . . . H 1196 0 0.078 80Spermotbamnion turneri (M ertens) Aresch . . . .. . . . . G . . . . M 0.313 310Z anardinul« andersonii (J. Ag .) Papenfuss .. . . . . . H 7674 0 0.039 40Zunardinula filiformis (Ky lin) Papenfuss . .. . . . . . . H 7671 0 0.078 80Z anardinul« lanceolata (Harvey) De Toni . ... . .. . H 7672 0 0-02 20

H 7673 0 0.059 60Z anardlnul« Iyallii (Harvey) D e Toni . . . . . . . .. . . H 7675 0 0.117 120

H 1050 0 0 0

* Collector: B, A. J. Bernarowicz; D , M . S. D ory; G, M . R . Grimm ; H , 1. H orow itz .t Location : B, Bermuda; H, Hawaii; M, Woods Hole, Mass achusetts; 0, Cape Arago, O regon.

rreated remain for the most part in the herb­aria of the various collectors. The collectorand collector's nu mber, where given, areshown in Tab le l.

As is shown in Table 1, very little iodinewas detected in the Chlorophyta, a findi ngwhich is in agreement with the data of otherinvestigators. Phaeophyta such as Laminariaand Desmarestia had the highest concentra­tions of iodine. H owever, these genera arelarge forms difficult to maint ain in the labor­atory. Asparagopsis and Plumaria, bo th Rhodo­phy ta, sto re iodine in cons iderable amo untsand have the advantage of convenient cultura lsize.

A variation of iodine conten t was fou nd indifferent thalli collected from th e same loca l­ity. For example, one sample of Laminariaagardhii collected from Woods Hole showedno iodine while other specimens of the samespecies from the same vicinity showed anaccumulation of 5,000 parts per million.Turrenti ne (1912) records similar variationswith L. saccharina.

In a consideration of the iodine conte nt ofthe same thallus, marked differences werenoted by Turrentine (1912), Cameron (1915),

and Black (1948). Fritsch (1945) reportedtha t the greatest accumulation of iodine wasin the actively growing cells at th e base of theblade. Tab le 1 shows that th e blades of L.sinclairii contained 5,000, hap tera andrhizoids1,880, and stipe 3,750 parts per million. Iodinedeterminations of other species of Laminariapro vided simi lar results. Thus, in Laminaria,there appears to be an analogy between theactivi ty of gtOwth-regulating substances ob ­served by Williams (1949) and th e distri bu­tion and amounts of iodine present .

Table 1 also indica tes that two phases ofLaurencia obtusa contained different amo untsof iodi ne-the yellow ph ase three times asmuch iodine as th e green phase. The sameappears to be true of two gtOwth forms ofAmphiroa fragilissima. A fine form containedmore th an five times as much iod ine as acoarse form. A potential taxonomic use of theiodide test is suggested here as a supplementto the vague morpho logical criteria currentlyused in separa ting the infrageneric taxa ofsuch genera.

The data presented indicate that Asparagop­sis and Plumaria wo uld be the mo st suitablespecies for further investigation. Th eir adap-

322

tation in this study allows the conjecturethat they may be readily adaptable to methodsof culture, iodine uptake, plant metabolism,and tracer studies.

A listing of algae which gave negativetests far iodine is presented here. These spe ­cies represent approximately 50 per cent ofall organisms tested. The source of the sam ­ples is as indicated in Table 1.

LIST OF SPECIES YIELDING NEGATIVE

IODINE CONTEN T

CyanophytaCalothrixconfervicola (Roth) Ag. ex. Born.

& Flah MLyngbyamajuscula "(Dillwyn) Harvey ex.

Gomer' HChlorophyta

Boodlea composita (Harvey) Brand HCaulerpa crassifolia (c. Ag .) J. Ag BCaulerpa peltata (Turner) Lamour BCaulerpa racemosa var. laetevirens (M ont .)

Weber-van Bosse BCaulerpa sertularioides (Gmelin) H owe BCaulerpa verticillata J. Ag BCaulerpa webbiana Mont H

. Chaetomorpha antennina (Bory) Kuetz HCladophora sp HCladophoropsis membranacea (c. Ag. )

B¢rg BCodium decorticatum (Woodw.) Howe BCodium fragile (Suringar) Hariot 0Cympolia barbata (1.) Lamour BEnteromorpha clathrata (Roth) Grev 0Enteromorpha intestinalis (1.) Link 0Enteromorpha linza var. flexicaulis Doty . . 0Halimeda discoidea D ecaisne HMonostromagrevillei (Thuret) Wittr 0Spongomorpha eoalita (Rupr.)' Coll ins 0Udoteaflabellum (Ellis & Solander) Howe .BUlva angust« Setch . & Gard 0Ulva fasciata D elile H

BUlva lactuca 1. M

HUlva lobata (K uetz.) Setch , & Ga rd 0Urospora penicilliformis (Roth) Aresch 0

PACIFIC SCIENCE, Vol. VI, October, 1952

Vaucheria tburetii Woronin 0Phaeophyta

Aegira virescens (Carm .) Setch. & Gard . . .MColpomeni« sinuosa (Roth) D erbes & Soc

lier BCostaria mertensii J. Ag 0Dictyopteris delicatula Lamour BDictyopteris justii Lamour BDictyota dentata Larnour BDictyota divaricata Lamour BDilophus guineensis (K uetz.) J. Ag , . .BEctocarpus indicus Sonder. HEgregia menziesii (Turner) Aresch 0Heterochordaria abietina (Rupr.) Setch . &

Gard 0Hydroclathrus clathratus (Bory) Howe BIlea fascia (Mueller) Fries 0

MLeathesia dilformis (1.) Aresch : M

oPadina commersonii Bory HPadina pavonia (1.) Gaillon BPadina senctae-crucis B¢rg BPocockiella variegata (Lamour.) Papenfuss .BPunctaria latifolia Grev MScytosiphon lomentaria (Lyng bye) J. Ag 0

MSpatoglossum schroederi (M ertens) J. Ag BZonaria zonalis (Lamour.) Howe B

RhodophytaAcanthophora spicifera (Vahl) B¢rg BAgardhiella tenera (J. Ag. ) Schmitz MBangia oermicularis Harvey 0Calloph.yllis crenulata Setch 0Callophyllis megalocarpa Setch . & Gard 0Ceramium paciftcum (Collins) Kylin 0Ceramium rubrum (H udson) C. Ag 0Ceramium tenuissimum (Lyngbye) J. Ag HChampia parvttla (c. Ag. ) H arvey MChrondrus crispus (1.) Stackh MChrondia sedifolia Harvey MConstantinea simplex Setch 0Cumagloia andersonii (Farlow) Serch . &

Gard 0Delesseria deeipiensJ. Ag 0Dilsea californica (J. Ag. ) Schmitz 0Dumontia incrassata (M ueller) Lamour. . .M

1i

Iodine Content of Algae - GRIMM

Endocladia muricata (H arvey) J. Ag 0Erythrophyllttm delesserioides J. Ag 0Eucbeuma isiforme (c. Ag. ) J. Ag BFarlowia mollis (Harvey & Bailey) Farlow

& Setch 0Galaxattra cylindrica (Ellis & Solander)

Lamour. BGalaxaar« marginata (Ellis & Selander)

Lamour BHalymenia formosa Kutz HKylinia sp '.HL aurentia palisada Yamada HLiagora farinosa Lamour. BLiagora maxima Butters HLiagora valida Harvey B

HLomentaria baileyana (H arvey) Farlow . .. MNemalion mttltifidllm (Weber & M ohr) J.

Ag MOpttntiella californica (Farlow) K ylin 0Petrocelis franciscana Setch. & G ard 0Phy/lophora brodaei (Turner) J. Ag MPolysiphonia collinsii Hollenberg 0Polysiphonia fibrillosa Grev MPolysiphonia ·harveyi Bailey MPolysiphonia paniculata M ont 0Polysiphonia variegata (c. Ag .) Zanardini .MPorphyra nerocystis Anderson 0Porphyra perforata J. Ag 0Porphyra umbilicalis (1.) J. Ag MPorphyra variegata (K jellm .) H us " . . 0Pterosiphonia bipinnata (Post . & Rupr.)

Falken 0Rhodymenia pacifica K ylin 0Rhodymenia palmata (1.) Grev MSchizymenia pacifica K ylin 0

.Spyridia spinella Sander H

323

Spyridia filamentosa (W ulf.) Harvey . . . . .MB

Tburetia borneti Vickers BTrichogloea subnuda H owe HIJ7ttrdemannia miniata (D rap.) Feldm an &

Hamel. B

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BLACK, W . A. P. 1948. The seaso nal variationin chemical const itution of some of th esub-littoral seaweeds common to Scotland .Soc. Cbem. Lndus., J ottr. 67 : 165- 176.

CAMERON, A. T. 1914. Cont ributions to the .biochemistr y of iodine . I. The distributionof iodine in pla nt and animal tissues . [our.BioI. Chem. 18 : 335-380.

- - - 1915. Contributions to th e biochemis­try of iodine. II. The distribut ion of iodinein plant and anima l tissues . [our. BioI.Chem. 23: 1- 39.

CHAPMAN, V. J. 1950 . Seaweeds and their uses.xiv +287 pp ., 20 pls. M ethuen & Co. , Ltd .,London.

FRITSCH, F. E. 1945. The structure and repro- .duction of the algae. Vol. 2. xiv+ 939 pp.,2 maps. University Press, Cambridge .

SMITH, G . M ., ED. 1951. Manttal of phycology.375 pp ., 48 pls, Chronica Botanica Co.,Waltham, M assachusetts.

T URRENTINE, J. W . 1912. The com po sitionof kelps . Appendix P. In Fertili zer resourcesof th e United States. F. K . Cameron. UnitedStates 62nd Congress, 2nd Session, Senate Doc.190: 217-231, G overnment Printing Office,Wa shington .

WILLIAMS, 1. G . 1949. Growth-regulating. subs tances in Laminaria agardhii. Science

110: 169.