There are those who consider ques-tions in science which have no un-equivocal, experimentally determinedanswer scarcely worth discussing. Suchfeeling, along with conservatism, mayhave been responsible for the long andalmost unchallenged dominance of thesystem of two kingdoms-plants andanimals-in the broad classification oforganisms. The unchallenged position ofthese kingdoms has ended, however;alternative systems are being widely con-sidered (1-18) and are appearing inmany introductory biology texts (19-24). My purpose in this article is to dis-cuss the merits of two classificationswhich depart from the traditional twokingdoms, the systems of Copeland (1-3) and Whittaker (4, 5).

Two-Kingdom System

Man is terrestrial, and he sees aroundhim two major groups of organisms ofvery different adaptation to nutrition onland-the photosynthetic, rooted, higherplants, and the food-ingesting, motile,higher animals. So distinct in way oflife, direction of evolution, and kind ofbody organization are these groups thata concept of dichotomy-plants versusanimals-is almost inescapable if theyare considered by themselves. The twogroups became the nuclei around whichconcepts of the plant and animal king-doms were developed by early natural-ists. The kingdoms have been part ofthe formal classification of living thingssince Linnaeus (25).

Mosses, liverworts, and macroscopicalgae are clearly plants in their photo-synthetic and nonmotile way of life,and (though the photosynthetic processitself was not understood by earlynaturalists) these forms were grouped

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with the higher land plants. The higherfungi on land are nonmotile, and theirapparently "rooted" manner of growthsuggested the plants. It thus seemedreasonable to assign fungi to the plantkingdom, and some students believedthat they had evolved from algae. Thewealth of unicellular life discovered bymicroscopists offered greater difficulty.Some forms were motile and ingestedfood, however, and were naturally re-garded as one-celled animals or proto-zoans. Others were nonmotile andphotosynthetic, hence one-celled plants.There remained a wide range of uni-cellular forms in which nonmotility andflagellate or pseudopodial motility, andingestive, photosynthetic, and absorp-tive nutrition, were combined in variousways which were neither clearly plant-like nor animal-like. In a number ofcases plant-like and animal-like unicellswere connected by a series of closelyrelated intergrading forms within thesame major taxon. There remained alsothe bacteria which, though few are pho-tosynthetic and many are motile,seemed better treated as plants be-cause of their walled cells. The plantand animal kingdoms are prod-ucts of a process of concretion, bywhich groups of organisms which wereaquatic, or fungal, or microscopic, ormore than one of these, were addedaround the nuclear concepts of plantand animal derived from higher landorganisms.

It was recognized that the two-kingdom system came into difficulties intreatment of the unicellular organisms,since some groups of these were claimedboth for the plant kingdom by botanistsand for the animal kingdom by zoolo-gists. The system seemed, however, areasonable treatment of the living worldin terms of two kingdoms and evolu-

New Concepts of Kingdomsof Organisms

Evolutionary relations are better represented by newclassifications than by the traditional two kingdoms.

R. H. Whittaker

prefer the more familiar term "Protista"for the second concept. Different inter-

The author is professor of biology in the Sec-tion of Ecology and Systematics, Cornell Uni-versity, Ithaca, New York 14850.

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tionary directions (Fig. 1). In time thesystem seemed not reasonable butaxiomatic; suggestions of other king-doms were regarded as the idiosyncra-sies of individuals. There were such sug-gestions, however, as the limitations ofthe two-kingdom system became moreevident. I have reviewed proposals forother kingdoms in more detail elsewhere(5).

Limitations of the Two-Kingdom System

The difficulties of the two-kingdomsystem may be summarized in relationto four points.

1) The protists. The most obviousdifficulty is that for which we useEuglena and its relatives as the ex-emplar for students-the intergradingcombinations of plant and animal char-acters, the fusion of the kingdoms,among unicellular organisms. Because ofthe impossibility of clear division of theunicells into plants and animals, a num-ber of authors suggested third kingdomsof lower organisms (26-32). Hogg (26)observed the intergradation of plantsand animals among lower forms andproposed for them the Regnum Primi-genum and the term "Protoctista."Haeckel (29) proposed separating thelower organisms as the kingdom "Pro-tista." Haeckel included the sponges inthis kingdom in one treatment (29), andthe fungi in another (30); but the king-dom comprised primarily, and in latertreatments (31, 32) only, the unicellularorganisms.

Although content of the third king-dom of lower organisms and use of"Protoctista" and "Protista" have varied,two principal possibilities may be dis-tinguished. The lower kingdom mayeither comprise only unicellular orga-nisms (including those forming coloniesof unicells), the kingdom Protista ofHaeckel (29-32) and others (33, 20, 21,5, 14), or the lower kingdom may com-prise the unicells plus other organismswhich lack the kind and degree of tissuedifferentiation characteristic of higherplants and animals, thus including fungiand most or all algae, the kingdomProtoctista of Hogg (26) and Copeland(3). (In either of these concepts bacteriaand blue-green algae may be excludedas indicated below.)Some authors (10, 12, 15, 19, 22)

pretations of the Protista are possiblefrom Haeckel's own treatments of thekingdom. Protists are conceived (29, 31)as unicellular and as organisms whichform no tissuLes [in a later statement(32), ". . . organisms which as a ruLleremain uinicellular throughouLt life(monobia), less frequlently they formloose cell communities (coenobia) byrepeated cleavage, bitt never realtissues."]. They are contrasted with thetissue-forming organisms of the king-doml Histonia, comprising the Meta-phyta (incluiding higher fungi, higheralgae, and higher land plants) andMetazoa (multicellular animals).From this contrast of unicellular and

tissue-forming conditions, the difficuLltyhas restulted. Kingdoms defined by theunicellular condition and by somatictissue differentiation exclude a broadmiddle ground, occupied by organismswhich lack evident somatic tissue differ-entiation bitt are clearly multicellularor multinItcleate as organisms, as indi-cated by cell differentiation and inter-dependence (sponges), or somatic organdifferentiation (higher algae, mosses), ordifferenitiation of reproduLctive tissuesand organs (higher fungi). I suggest inconsequence that the Protista may bestbe defined not by lack of tissue differen-tiation but by lack of tissue formation-absence of integration of cells (ornuclei and cytoplasm) into the one ormore tissues of a multicellular (ormLiltinucleate) organism. Tissue differ-entiation in somc lower multicellularand multinucleate organisms (somealgae, fungi, and sponges) is limited toa single somatic tissue, plus reproduc-tive cells, tissuLes, or organs distinctfrom it. For clarity and consistencyterms and concepts for the lower king-doms will be distinguished throughoutthis article. The kingdom Protista com-prises organisms which are unicellularor unicellular-colonial and which formno tissues. The alternative kingdom.Protoctista, will be conceived, as byCopeland (3), as a broader kingdom ofunicellular, mntlticellular, or muLltinu-cleate organisms which mostly lacksomiatic tissue differentiation, includinghigher algae and fungi.

2) The mnioncrealns. Haeckel (29-32)regarded the bacteria and blue-greenalgae as protists without nuclei andplaced them in the group Moneres orMonera, subordinate to the kingdomProtista. Recent work has made moreevident the profound differences oforganization between bacterial cells andthose of other organisms (19, 34). Cellsof bacteria and blte-green algae lack

10 JANUARY 1969

mitochondria and plastids, nuclcarmembranes and mitotic spindles, theendoplasmic reticulum and Golgi ap-paratus, vacuoles, and advanced (94 2-strand) flagella, among the organellescharacteristic of the cells of other orga-nisms. Nuclear material is probably asingle strand of DNA without histones,dividing by means other than mitosis;sexLual reproduction is apparently bothinfrequtent and incomplete in the sensethat only partial recombination ofgenetic material of cells may result frombacterial conjugation and other proc-esses. Bacteria and blue-green algaealso resemble one another and differfrom other organisms in biochemicalcharacteristics, inCluding their methodof ornithine synthesis, the apparentlylimited oCcurrence of sterols, sensitivityto antibiotics, and cell-wall composition(35, 36).

These contrasts between the pro-caryotic cells of bacteria and blue-greenalgae, and the eucaryotic cells of otherorganisms, define the clearest, mosteffectively discontinuous separation oflevels of organization in the living world(19, 37, 38). The idea of ancient cellularsymbioses, and the evolution of chloro-plasts from blue-green algae and mito-chondria from aerobic bacteria living

within other unicells, offers an attractivesuggestion on the origin of part of thisdifference of organization (39). Margulis(38) has added a further, more strikinghypothesis-origin of the (9+2-strand)flagellum and the centriole and spindlefigure of the eUcaryotes from a sym-biotic, spirochaete-like organism-andon the basis of this hypothesis and othercytological and biochemical evidenceconsidered the phylogenetic pattern ofthe living world. Symbiotic origin of theeuLcaryotic cell is accepted as a hypoth-esis here, but the difference betweenprocaryotes and eucaryotes remains aline of division deserving recognition ina current system of broad classification.The bacteria are not plants in eitherway of life or evolutionary relation toother plants; and the blue-green algae,which are functional plants, are widelyseparated in their cell organization fromall other plants. Most authors who con-sider alternatives to the two-kingdomsystem separate the bacteria and blue-green algae as either a subkingdom ofthe Protista (9, 5) or more commonlyas the kingdom Monera (1, 7, 8, 10,12-15, 22, 24) or Mychota (2, 3).

3) Tlhe fuiigi. Are the fungi plants, ifthe bacteria are not? There are reasonsto juLdge that they are not (40-45). (i)

Plantae Animalia

Fig. 1. A simplified evolutionary scheme of the two-kingdom system as it might haveappeared early in the century. The plant kingdom comprised four divisions-Thallophyta(algae, bacteria, fungi), Bryophyta, Pteridophyta, and Spermatophyta. Only majoranimal phyla are indicated.

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They were separately derived from theunicells. Although earlier authors specu-lated on derivation of fungi from algae(46, 47), it now seems likely that thelower fungi (chytrids and others) in-clude a number of groups polyphyletic-ally derived from different colorless flag-ellate ancestors, and that the higherfungi (Ascomycetes, Basidiomycetes)were derived from one of these groupsof lower fungi (40, 43, 48-50, 36). (ii)Their organization is very different from,and nonhomologous with, that of theplants (44, 45, 4, 5). The characteristicsomatic organization of the higher fungi,the syncytial mycelium with protoplasmflowing in a system of tubes, couldhardly be less like that of the trueplants. Reproductive structures and thedicaryotic condition (combining nucleiof different individuals in the samesyncytial or multinucleate tissue withoutnuclear fusion) are different from, andnonhomologous with, the reproductivestructures and diploid condition of thehigher plants. Many lower fungi are notmycelial but have a different organiza-tion of the chytrid type-a globularspore-case with (in many species) slenderprotoplasmic rhizoids extending into thefood source. The spore-case is at firstunicellular, then becomes multinucleate,and finally many-celled as the flagellatedzoospores or reproductive swarmers areformed and released. It is probable thatonly convergences relate the structuresand life cycles of the fungi to the algaeon the one hand, and to the mycelialbacteria (actinomycetes) on the other.(iii) The nutritive mode and way of lifeof the fungi differ from those of theplants. So far as is known the fungihave been wholly nonphotosyntheticfrom their origin from unicells to theirpresent diversity of forms. Fungicharacteristically live embedded in afood source or medium, in many casesexcreting enzymes for external diges-tion, but in all cases feeding by absorp-tion of organic food from the medium.Their organization, whether mycelial,chytrid, or the unicellular of yeasts, isadapted to this mode of nutrition.

Convenience still places the fungi inthe plant kingdom in many textbooks.It may be fair, however, to observe theextent to which this is a position ofconvenience; for the fungi are aseparate, major group of organisms ofdifferent origin, different direction ofevolution, and different organization inadaptation to a different primary nutri-tion from that of the plants. The fungiare separated from the plants in most

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recent proposals on broad classificationand are placed either in the kingdomProtoctista (3, 9, 13, 19, 22) or in aseparate kingdom Fungi (5, 8,14).

4) Nutritional modes. When thesignificance of bacteria and fungi innatural communities was unrecognized,it seemed reasonable to think of twomajor modes of nutrition for the king-doms-ingestive in the animals, and inthe plants primarily photosynthetic (andsecondarily absorptive). There are, how-ever, not two principal modes of nutri-tion but three-the photosynthetic, ab-sorptive, and ingestive. The three modeslargely correspond to three major func-tional groupings in natural communities,the producers (plants), reducers (sa-probes, that is, bacteria and fungi), andconsumers (animals) (4, 5, 51). The im-portance of the reducers in the cyclingof materials in ecosystems appears to ex-ceed that of the consumers. In evolutioningestive nutrition was a developmentsecondary to the absorptive nutrition ofmost monerans and many eucaryoticunicells. Both protozoans with foodvacuoles and metazoans with digestivetracts have probably evolved from ab-sorptive flagellates, and in this evolutioninternalized the process of food absorp-tion and added to it the process of in-gestion. One may consider that theeucaryotic plants also have internalizedthe absorption of food through a mem-brane, that surrounding the chloroplastas symbiont and organelle. The threemodes of ntutrition imply different logicson which the evolution of structure inhigher organisms was based (44, 4, 5).

Photosynthesis has implied evolutionamong higher plants of: (i) nonmotilelife with structure based on walled cellsdifferentiated into organs including (ii)blades or leaves as organs for concentra-tion of chloroplast-containing cells andphotosynthetic activity, and (iii) stipes orstems as organs to support these infavorable light conditions, with (iv)holdfasts to hold the plant in its placeor roots to hold the plant and provideaccess to soil water and nutrients, and,(v) in the latter case, vascular tissue toconduct materials between roots andleaves by way of the stem, hence (vi) anintermediate level of somatic tissuedifferentiation (higher than fungi, lowerthan animals). The direction as statedhas been realized to different degrees ina number of independent evolutionarylines of plants including higher greenalgae, red algae, brown algae, mosses,and vascular plants.

Ingestion in animals has implied evo-

lution of: (i) a motile, food-seeking lifein most cases, requiring evolution ofboth (ii) the sensory-neuro-motor com-plex of tissues, organs, and organ sys-tems which make possible perception ofand response to food and (iii) the diges-tive-circulatory-excretory complex forfood and waste processing and trans-port, and in larger forms a system ofexternal respiration; these systems im-plying, and serving to support (iv) acomplexly differentiated structure of di-verse, highly specialized tissues of wall-less cells, functioning at high metaboliclevels in support of active life, the com-plex structure requiring in turn (v)highly developed mechanisms of inte-gration and internal regulation throughthe nervous, circulatory, and endocrinesystems. The logic has led to levels ofstructural and functional complexityamong animals which are withoutparallel among other organisms, andultimately toward complexity of in-herited behavior or toward intelligence.It has led also to a diversification ofstructural designs without clear relationto one another, recognized by systema-tists in the large number of animalphyla, which is without parallel in othergroups of organisms. (There are 20phyla listed for the Eumetazoa in Table1, and some authors recognize 25 to 30.)

In adaptation to absorption higherfungi have evolved: (i) nonmotile lifeembedded in the food supply, with (ii)mycelial organization combining maxi-mum surface of contact with food withfree movement of food and protoplasmthrough the mycelial system, while (iii)only the reproductive organs emergefrom the food supply to release spores.The low level of somatic tissue differen-tiation in the fungi is as much a corre-late of their way of life as the high levelin the animals is of theirs. Diversifica-tion of the higher fungi is expressed,rather, in reproductive structures; andtheir classification is largely based onthese.

These logics based on nutrition arethe central meaning of the plant andanimal kingdoms as Jpng recognized,and of the fungi as a third major direc-tion of evolution. The same nutritivemodes necessarily appear among theunicells. Absorption is the principal nu-tritive mode among the bacteria; butblue-green algae and certain bacteriaare photosynthetic or chemosynthetic,while Bdellovibrio and some of themyxobacteria are motile (but absorptive)predators on other unicells. All threemodes and all possible transitions and

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combinations are developed among theeucaryotic protists, but specialized pro-tists include plant-like walled cells withchloroplasts, diverse absorptive forms,and protozoans with organelles for in-gestion and internal digestion, sensoryperception, and movement.

Neither the intergradation of thesemodes among protists nor specializedexceptions among higher organisms-plants which catch insects or micro-crustaceans, fungi which trap nema-todes, animals and plants which feed asabsorptive parasites, and the symbioticrelations of lichens, corals, and so forth-should obscure the significance of thenutritive modes in the broad evolution-ary pattern of the living world.

The Copeland Four-Kingdom System

Given these developments, Copeland(1-3) has designed a successful and nowrather widely followed system of fourkingdoms. The kingdoms as Copeland(3) defines them are: (i) Kingdom My-chota or Monera. Organisms withoutnuclei, the bacteria and blue-greenalgae. (ii) Kingdom Protoctista. Nucle-ate organisms not having the charactersof plants and animals, the protozoa, thered and brown algae, and the fungi. (iii)Kingdom Plantae. Organisms in whosecells occur chloroplasts, being plastids ofbright green color, containing the pig-ments chlorophyll a, chlorophyll b, caro-tin, and xanthophyll, and no others; andwhich produce sucrose, true starch, andtrue cellulose. (iv) Kingdom Animalia.Multicellular organisms which pass dur-ing development through the stagescalled blastula and gastrula. They aretypically predatory, and accordinglyconsist of unwalled cells and attainhigh complexity of structure and func-tion.

Disposition of the green algae(Chlorophyta and Charophyta) in thefouLr-kingdom system is a problem. InCopeland's (1-3) system they are as-signed to the kingdom Plantae becausethey are part of the evolutionary lineleading to the higher green plants, andby defining the kingdom by some bio-chemical characters shared by orga-nisms of this evolutionary line. The sys-tems of Rothmaler (52) and Barkley(53) correspond in design to that ofCopeland, but use different names anddefinitions of the kingdoms; theseauthors and others (9, 10, 15, 19, 22)assign the green algae to the kingdomProtoctista or its equivalent. When the

10 JANUARY 1969

kingdom of higher plants is thus nar-rowed to include only the land plants(bryophytes and tracheophytes), theterms "Metaphyta" or "Embryophyta"seem preferable for this kingdom.Authors other than Copeland haveused one of these terms, along withthe coordinate term "Metazoa" for thehigher animals, and have preferred theterm "Monera" to "Mychota."With these changes as Copeland's sys-

tem has been applied by others (15, 22),the four kingdoms may be character-ized:

1) Kingdom Monera. Procaryoticorganisms, with unicellular or simplycolonial organization (bacteria and blue-green algae).

2) Kingdom Protoctista (Protista ofsome authors). Lower eucaryotic orga-nisms, with organizations which are uni-cellular, unicellular-colonial, syncytial,or multicellular without advanced tissuedifferentiation (algae other than the blue-greens, protozoans, slime molds, andfungi).

3) Kingdom Metaphyta or Embryo-phyta. Higher multicellular eucaryoticorganisms with walled cells and greenplastids. Levels of cell, tissue, and organdifferentiation range from limited(Bryophyta) to intermediate (Tracheo-phyta); digestive cavities and motility bycontractile fibers are lacking (land plantsand aquatic plants derived from them).

4) Kingdom Metazoa. Higher multi-cellular eucaryotic organisms with wall-less cells and without plastids, mostlywith internal digestive cavities, motilityby means of contractile fibers, and ad-vanced cell, tissue, and organ differen-tiation (multicellular animals).

Copeland recognizes a single phylumin the Monera and does not discussphyla of the Metaphyta and Metazoa.His phyla in the Protoctista are: (i)Rhodophyta (red algae), (ii) Pyrrophyta(dinoflagellates and cryptomonads, plusthe euglenoid organisms), (iii) Phaeo-phyta (yellow and brown algae, includ-ing the phyla Chrysophyta, Phaeophyta,Oomycota, and Hyphochytridiomycotaof Table 1), (iv) Opisthokonta (chytridsand relatives, Chytridiomycota in Table1), (v) Inophyta (higher fungi, includingthe Zygomycota, Ascomycota, and Ba-sidiomycota), (vi) Fungilli (sporozoans,including the Cnidosporidia), (vii) Pro-toplasta (amoeboid and flagellate proto-zoans, slime molds, and plasmodio-phores), and (viii) Ciliophora (ciliatedprotozoans and suctorians). To these,some authors would add (ix) Chloro-phyta, (green algae, including the

Charophyta). Others may prefer alsoto treat the euglenoid organisms sep-arately, or in the Chlorophyta, andto treat the Oomycota as a fungalphylum separate from the algal lineof the Chrysophyta and Phaeophyta[in which, as the Chromophyta, Chade-faud (11) also includes the dino-flagellates and cryptomonads].The Copeland system has advantages

over the two-kingdom system whichhave led to its acceptance in currenttextbooks. The traditional kingdoms,which extend through all levels of orga-nization, are almost undefinable as unitsof classification. The traditional plantkingdom in particular, with its range oforganization from monerans to higherplants and higher fungi and its inclusionof groups with fundamentally differentdirections of evolution in relation to nu-

trition, is difficult to define (see, how-ever, 17). In relation to it Dillon (18)has a point in carrying its inclusivenessone step further and suggesting thatthere is really only a single kingdom,that of the plants, within which are anumber of lines of evolution toward theforms we regard as animals or as fungi.Copeland's four kingdoms are, in con-trast (especially if the green algae aretransferred to the protoctists), clearlydefinable in terms of kinds of organiza-tion. For the professional biologist theyare workable taxa of broad classifica-tion; for the teacher of biology they areeffective means of grouping phyla fordiscuission.

Limitations of the Copeland System

The system cannot, however, escapecertain difficulties; three limitationsaffect it:

1) Of the three major nutritive direc-tions two, photosynthesis and ingestion,provide the evolutionary meaning of thekingdoms of higher plants and higheranimals. The third, absorption as thenutritive theme of the higher fungi, isnot given coordinate recognition; andthe place of these organisms in thebroad evolutionary pattern of the livingworld is not clarified.

2) For the one undrawable line be-tween plant and animal unicells whichis done away with, another of almostequal difficulty is substituted, that be-tween protoctists and higher organisms.The Protoctista may be thought pri-marily unicellular, but the kingdom in-cludes evolutionary lines of varyingdevelopment into multicellular or muLti-

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nucleate organization and some phylawhich are primarily multicellular ormultinucleate. The consequence forclassification is illustrated in an excellenttreatment by Hutchinson (15), in whichthe difficulties are clearly stated. Thekingdom Protista is, however, defined as"single celled or colonial organisms."The kingdom includes the higher fungiand the green, red, and brown algae.The definition is that of the kingdomProtista but the content is that of thekingdom Protoctista and belies the defi-nition. Hutchinson's (15) further specifi-cation, "if colonial usually with littletissue differentiation," does not help. Anorganism with tissue differentiation isnot a colony of unicells; and the higheralgae and fungi are by no means colo-nies of unicells despite low levels oftissue differentiation.

It is consequently appropriate to con-ceive the Protoctista as a very wide

range of organisms with a very widerange of intermediate levels of orga-nization-above the procaryotes, butbelow the vascular plants and higheranimals. The line between protoctistsand higher plants and animals is thusdrawn primarily by degree of tissuedifferentiation. The brown algae areplaced below this line for lack ofmarked tissue differentiation in most,even though organ differentiation (hold-fast, stipe, and blade) appears in many,and a differentiated central vasculartissue occurs in some. The fungi areplaced below the line because of theirlimited somatic tissue differentiationdespite the elaboration of reproductiveorgans and tissues (and the specializedsomatic rhizomorph tissue in some).Mosses, liverworts, sponges, and meso-zoans are best grouped with more ad-vanced members of the plant andanimal kingdoms despite lack of or

limited tissue differentiation. An uneasyboundary between protoctists and higherorganisms results (Fig. 2).

3) The kingdom Protoctista lacks theunity and clarity of definition which thesystem achieves for the other three king-doms. So wide is the range of organiza-tion among the protoctists that thesemay seem less a kingdom than a con-federation of those excluded from theMonera, land plants, and multicellularanimals. Copeland's phyla of protoc-tists are, however (even if some changesin them are desirable), an effectivedivision of the lower eucaryotic orga-nisms into broadly defined evolutionarylines and groupings.

In fairness these points should berecognized to reflect not so much faultsof the Copeland system as faults of theliving world as a subject of classifica-tion. There is no good way to separatethe lower and higher eucaryotic orga-

Table 1. A classification of the living world from kingdoms through phyla.

Kingdom Monera (70)Procaryotic cells, lacking nuclear membranes, plastids, mitochondria, and advanced (9 + 2-strand) flagella; solitary unicellular or colonial-

unicellular organization (but in one group mycelial). Predominant nutritive mode absorption, but some groups are photosynthetic or chemo-synthetic. Reproduction primarily asexual by fission or budding; protosexual phenomena also occur. Motile by simple flagella or gliding,or nonmotile.

Branch Myxomonera (71). Without flagella, motility (if present) by glidingPhylum Cyanophyta (72), blue-green algaePhylum Myxobacteriae (72), gliding bacteria

Branch Mastigomonera (71). Motile by simple flagella (and related nonmotile forms)Phylum Eubacteriae (72), true bacteriaPhylum Actinomycota (72), mycelial bacteriaPhylum Spirochaetae (72), spirochetes

Kingdom Protista (73)Primarily unicellular or colonial-unicellular organisms (but simple multinucleate organisms or stages of life cycles occur in a number

of groups), with eucaryotic cells (possessing nuclear membranes, mitochondria, and in many forms plastids (9 + 2)-strand flagella, andother organelles). Nutritive modes diverse-photosynthesis, absorption, ingestion, and combinations of these. Reproductive cycles varied,but typically including both asexual division at the haploid level and true sexual processes with karyogamy and meiosis. Motile by ad-vanced flagella or other means, or nonmotile (74).

Phylum Euglenophyta, euglenoid organismsPhylum Chrysophyta, golden algaePhylum Pyrrophyta, dinoflagellates and cryptomonadsPhylum Hyphochytridiomycota (75), hyphochytridsPhylum Plasmodiophoromycota (75), plasmodiophoresPhylum Sporozoa, sporozoansPhylum Cnidosporidia, cnidosporldiansPhylum Zoomastigina, animal flagellatesPhylum Sarcodina, rhizopodsPhylum Ciliophora, ciliates and suctorians

Kingdom Plantae (76)Multicellular organisms with walled and frequently vacuolate eucaryotic cells and with photosynthetic pigments in plastids (together with

closely related organisms which lack the pigments or are unicellular or syncytial). Principal nutritive mode photosynthesis, but a number oflines have become absorptive. Primarily nonmotile, living anchored to a substrate. Structural differentiation leading toward organs of photo-synthesis, anchorage, and support, and in higher forms toward specialized photosynthetic, vascular, and covering tissues. Reproduction pri-marily sexual with cycles of alternating haploid and diploid generations, the former being progressively reduced toward the higher membersof the kingdom.Subkingdom Rhodophycophyta (77). Chlorophyll a and (in some) d, with r-phycocyanin and r-phycoerythrin also present, food storage

as floridean starch, flagella lacking.Phylum Rhodophyta, red algae

Subkingdom Phaeophycophyta (77). Chlorophyll a and c, with fucoxanthin also present, food storage as laminarin and mannitol, zoo-spores with two lateral flagella, one of whiplash and one of tinsel type.

Phylum Phaeophyta, brown algaeSubkingdom Euchlorophyta (78). Chlorophyll a and b, food storage as starch within plastids, ancestral flagellation two or more anterior

whiplash flagella.Branch Chlorophycophyta (79). Primarily aquatic, without marked somatic cell differentiation.

Phylum Chlorophyta, green algaePhylum Charophyta, stoneworts

Branch Metaphyta (80). Primarily terrestrial, with somatic cell and tissue differentiation.Phylum Bryophyta (81), liverworts, hornworts, and mossesPhylum Tracheophyta (82), vascular plants

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nisms, there are only different choices A Five-Kingdom System tista, Plantae, Fungi, and Animalia-ofwith different difficulties. Given level of the system developed in an earliertissue differentiation as the choice, the A different response to the problems paper (5). Somewhat related systemsassignment of the higher fungi and algae of the two-kingdom system is possible. have been used by Simpson (20), whoto the kingdom Protoctista and the In this solution: (i) The fungi are ac- places the fungi as well as the unicel-heterogeneity of the kingdom will cepted as a third kingdom of higher lular and higher algae in the kingdomfollow. The difficulties cannot be over- organisms, coordinate with the higher Plantae, and Pimentel (13), who sepa-looked, but they should not prevent plants and animals. (ii) The line between rates the Monera as a kingdom, groupsrecognition that this is a reasonable and these higher organisms and the protists protozoans, slime molds, and fungi asworkable broad classification of the is placed at the transition from the uni- the kingdom Protista, and assignsliving world, with marked advantage cellular to the multicellular and multi- eucaryotic algae and land plants to theover the two-kingdom system in its nucleate conditions. (iii) The higher kingdom Plantae.grouping of phyla by levels of organiza- algae are then placed in the plant king- The Monera were a subkingdom oftion. Copeland's is a major contribution dom along with the green higher plants. the Protista in the earlier treatment (5);to interpretation of the living world. There result the four kingdoms-Pro- current preference is for full separation

Table 1 (continued).Kingdom Fungi (83)

Primarily (excepting subkingdom Gymnomycota) multinucleate organisms with eucaryotic nuclei dispersed in a walled and often septatemycelial syncytium, plastids and photosynthetic pigments lacking. Nutrition absorptive. Somatic tissue differentiation absent or limited, re-productive tissue differentiation and life cycle elaboration marked in higher forms. Primarily nonmotile (but with protoplasmic flow in themycelium), living embedded in a medium or food supply. Reproductive cycles typically including both sexual and asexual processes; myceliamostly haploid in lower forms but dicaryotic in many higher forms.Subkingdom Gymnomycota (84). Deviant organizations including in life cycles separate cells, aggregations of cells, and sporulation stages.

Phylum Myxomycota (85), syncytial or plasmodial slime moldsPhylum Acrasiomycota (85), cellular or pseudoplasmodial slime moldsPhylum Labyrinthulomycota (85), cell-net slime molds

Subkingdom Dimastigomycota (86). Biflagellate (heterokont) zoospores present, chytrid to simply mycelial organization, cellulose walls.Phylum Oomycota (87), oosphere fungi

Subkingdom Eumycota (88). Predominantly mycelial organization, zoospores uniflagellate if present, chitin walls, other characters as statedfor kingdom.Branch Opisthomastigomycota (89). Uniflagellate (opisthokont) zoospores present, chytrid to simply mycelial organization, mainly aquatic.

Phylum Chytridiomycota (89), true chytrids and related fungiBranch Amastigomycota (90). Flagellated zoospores absent, simple to advanced mycelial organization (but secondarily unicellular in

yeasts), mainly terrestrial.Phylum Zygomycota (87), conjugation fungiPhylum Ascomycota (87), sac fungiPhylum Basidiomycota (87), club fungi

Kingdom Animalia (91)Multicellular organisms with wall-less eucaryotic cells lacking plastids and photosynthetic pigments. Nutrition primarily ingestive with

digestion in an internal cavity, but some forms are absorptive and a number of groups lack an internal digestive cavity. Level of organiza-tion and tissue differentiation in higher forms far exceeding that of other kingdoms, with evolution of sensory-neuro-motor systems andmotility of the organism (or in sessile forms of its parts) based on contractile fibrils. Reproduction predominantly sexual, haploid stages otherthan the gametes almost lacking above the lowest phyla (92).Subkingdom Agnotozoa (93). Nutrition absorptive and ingestive by surface cells, internal digestive cavity and tissue differentiation lack-

ing. Minute, motile by cilia.Phylum Mesozoa, mesozoans

Subkingdom Parazoa (94). Nutrition primarily ingestive by individual cells lining internal water canals. Cell differentiation present buttissue differentiation lacking or very limited; cells with some motility but the organism nonmotile.

Phylum Porifera, spongesPhylum Archaeocyatha (extinct)

Subkingdom Eumetazoa (95). Advanced multicellular organization with tissue differentiation, other characteristics of the kingdom.Branch Radiata (96). Animals of radiate or biradiate symmetry.

Phylum Cnidaria, coelenteratesPhylum Ctenophora, comb jellies

Branch Bilateria (97). Animals of bilateral symmetry.Grade Acoelomata (98)

Phylum Platyhelminthes, flatwormsPhylum Nemertea or Rhynchocoela, ribbon worms

Grade Pseudocoelomata (98)Phylum Acanthocephala, spiny-headed wormsPhylum Aschelminthes, diverse pseudocoelomate wormsPhylum Entoprocta or Kamptozoa, pseudocoelomate polyzoans

Grade Coelomata (98)Subgrade Schizocoela (99)Phylum Bryozoa or Ectoprocta, coelomate, ectoproct polyzoansPhylum Brachiopoda, lamp shellsPhylum Phoronida, lophophorate, phoronid wormsPhylum Mollusca, molluscsPhylum Sipunculoidea, peanut wormsPhylum Echiuroidea, spoon wormsPhylum Annelida, segmented or annelid wormsPhylum Arthropoda, arthropods

Subgrade Enterocoela (99)Phylum Brachiata or Pogonophora, beard wormsPhylum Chaetognatha, arrow wormsPhylum Echinodermata, echinodermsPhylum Hemichordata, acorn wormsPhylum Chordata, chordates

10 JANUARY 1969 155

of the Monera and the eucaryotic pro-tists into different kingdoms. Suchseparation was suggested as a possibility(5), and has been carried out in Grant's(14) treatment. The resulting five-king-dom system is similar to that of Jahnand Jahn (8) who, however, groupedthe higher algae with the protists andrecognized a kingdom Archetista forthe viruses. It is convenient, and may bejustifiable, not to treat the virusesas organisms. The five-kingdom systemof this author and Grant (14) may thenbe formulated as in Table 1. For clarifi-cation of taxa above the level of phylum,definitions of these are stated, and(though rules of taxonomic priority donot apply to them) sources and partialsynonymies of names are given. Therelation of the kingdoms to levels of or-ganization and directions of evolutionaffected by nutrition is shown in Fig. 3.The system differs from that pre-

viously presented (5) in (i) separationof the Monera from the Protista at thekingdom level, (ii) recognition of fivephyla, at least, in the Monera, (iii)

suggestion of branches as groupingsbetween major subkingdoms and theirphyla, and (iv) treatment of the fungi.For the last, the logic of evolutionarylines characterized by type of flagella-tion and biochemical characters (49,54-59, 36) has been carried through ina manner paralleling that now widelyaccepted for major groups of algae (36,60-64).The lower true fungi (Phycomycetes)

are believed to include four evolutionarylines of separate deprivation from flagel-lated unicells. These lines (with theirtypes of flagellation, the orders of Phy-comycetes in many treatments of thisgroup which they comprise, and thephyla to which they are here assigned)are: (i) The true chytrid line, zoosporewith a single posterior whiplash or acro-neme (naked) flagellum, the orderChytridiales (of walled chytrid orga-nization), together with the Blasto-cladiales and Monoblepharidales (withsimple hyphae or mycelia) derived fromthem; phylum Chytridiomycota [phy-lum Opisthokonta of Copeland (3),

Fig. 2. The Copeland system, with relationships of phyla to kingdoms and levels oforganization. In the Protoctista the names not in parentheses are Copeland's phyla;some major groups of protoctists that Copeland includes in these are indicated in paren-theses. The Opisthokonta equal the Chytridiomycota, the Inophyta equal the Amasti-gomycota, and the Fungilli equal the Sporozoa of Table 1 and Fig. 3. Only majoranimal phyla are indicated. Alternative treatments of the Chlorophyta and Charophytaare indicated; these are included in the Metaphyta by Copeland (3), but in theProtoctista by other authors.

156

Uniflagellatae of Sparrow (49)]. (ii)Hyphochytridiales, zoospore with asingle anterior tinsel or pantoneme(plume-like) flagellum, limited to wall-less chytrid organization; phylumHyphochytridiomycota. (iii) Plasmodio-phorales, two anterior whiplash flagellaof unequal length, naked plasmodialorganization; phylum Plasmodiophoro-mycota. (iv) The biflagellate line, zoo-spores with one whiplash and one tin-sel flagellum, the walled, chytrid-likeLagenidiales and the more advanced,mycelial Saprolegniales, Leptomitales,and Peronosporales derived from them;phylum Oomycota [Biflagellatae ofSparrow (49)]. An additional group (v)comprises forms which lack flagella andhave mycelial organization and hyphalconjugation, Mucorales and Entomoph-thorales; phylum Zygomycota.

There is suggestion in biochemicalevidence, notably sharing of the amino-adipic pathway for lysine synthesis, thatthe Chytridiomycota may have been de-rived from flagellates related to theEuglenophyta and are related also to thehigher fungi (58, 36). It seems likelythat the Zygomycota are derived, withloss of flagellate swarmers and furtherevolution of mycelial organization, fromthe Chytridiomycota, and that thehigher fungi (Ascomycota, Basidiomy-cota) are derived from the Zygomycota.The Chytridiomycota, Zygomycota,Ascomycota, and Basidiomycota in con-sequence represent the main axis ofevolution into the higher fungi, corre-sponding to that of the Chlorophyta,Charophyta, Bryophyta, and Tracheo-phyta in the plants. Flagellation and bio-chemical evidence indicate that theOomycota are a separate evolutionaryline, and that they more likely origi-nated from colorless forms related tothe Chrysophyta (58, 59, 3, 36).The Oomycota and Chytridiomycota

both include progressions from chytridto mycelial organization. Although Iconsider chytrids to be protists, I haveplaced these transitional phyla in theFungi, in parallel with the Chlorophytain the Plantae. The main axis of fungalevolution, from Chytridiomycota toBasidiomycota, is designated the sub-kingdom Eumycota; whereas the bi-flagellate line of the Oomycota is sepa-rated from these into the subkingdomDimastigomycota (in parallel with treat-ment of the Rhodophyta and Phaeo-phyta in the plant kingdom). The twolines which do not achieve mycelialorganization, the Hyphochytridiomycotaand Plasmodiophoromycota [which to-

SCIENCE, VOL. 163

gether are the Archimycetes of Giiu-mann (65, 57)] become phyla ofprotists, adjacent to absorptive andspore-forming organisms regarded asprotozoans, the Sporozoa and Cnidospo-ridia. Other wall-less fungi, the slimemolds, probably include at least threeseparate evolutionary lines from the uni-cellular condition (66), the true slimemolds (Myxomycetales), cellular slimemolds (Acrasiales), and cell-net slimemolds (Labyrinthulales). These have, fortheir separate origin and different orga-nization, been treated as three phyla andgrouped in a polyphyletic subkingdomGymnomycota.

This treatment results in a consider-able elevation of taxa; groups which areorders and classes in most other classi-fications become phyla here, in somecases separated into different branchesand subkingdoms. Recognition of threephyla of slime molds and seven of chy-trid and mycelial fungi is not, however,undue taxonomic inflation. The rangeof forms comprised in the fungi is wide,and the evidence of independent originof various fungal and slime mold groupsis clear. It is suggested that true fungiand slime molds are not best treated astwo phyla, that their designation as suchis in part a consequence of the effort totreat these groups within the plant orthe protoctist kingdom, and that the ex-pansion of each into a number of phylais more reasonable.

I believe that this system better rep-resents broad relationships in regard toboth levels of organization and nutritivemodes affecting kinds of organizationthan the two-kingdom and Copelandsystems. The red and brown algae andthe fungi may seem better placed, theformer as the higher plants of the sea,the latter as the third major evolution-ary direction among higher organisms.The system may further have much ad-vantage over the two-kingdom systemand some over the Copeland system inthe coherence and definable characterof the kingdoms as units of classifica-tion.

Limitations of the Five-Kingdom System

1) The distinction of the unicellularversus the multicellular and multi-nucleate conditions becomes the line ofdivision and difficulty. The phylumChlorophyta includes intergrading uni-cellular, colonial-unicellular, and multi-cellular forms and consequently violatesthe definition either of the Plantae (in

10 JANUARY 1969

which it is placed here) or of the Pro-tista (in which it could with equal jus-tice be placed). The slime molds crossthe distinctions of the kingdoms in bothnutrition and organization, and offer afree choice of treatment as aberrantfungi, eccentric protists, or very peculiaranimals. The line from the unicellularto multicellular and multinucleateorganization has been crossed by a num-ber of independent phyletic lines. I sug-gest that the transition between the uni-cellular and multicellular-multinucleateconditions is a better conceptual divisionbetween lower and higher organismsthan degree of tissue differentiation. Thepractical difficulties with borderlinegroups are at least as great, and may begreater, when the separation is based onthe unicellular condition rather thandegree of tissue differentiation. There isroom for different judgments on themerits of the two lines of division.

2) The three higher kingdoms arepolyphyletic. The Rhodophyta and

Plantae

Phaeophyta are recognized to havecome from different unicellular ances-tors than the Chlorophyta; the resem-blance of these three groups as higherplants results from convergence. Thereis reason also to suspect that thesealgae supplement photosynthetic nutri-tion by absorption (67). Judged by thecriterion of monophyly, the Plantae astreated here may seem less a kingdomthan an alliance of separate groupswhich are multicellular and predomi-nantly photosynthetic. It is also truethat the Metazoa in its traditional formis polyphyletic, with separate derivationto be assumed for two and probably allthree of its subkingdoms. The kingdomFungi includes, as indicated, probablytwo convergent groups of chytrid andmycelial fungi and three of slime molds.

3) Even with the multicellular algaeand higher fungi excluded, the Protistais a grouping of diverse organisms ofdisparate directions of evolution. Neces-sarily, some protist phyla are more

Fungi Animalia

0el

Fig. 3. A five-kingdom system based on three levels of organization-the procaryotic(kingdom Monera), eucaryotic unicellular (kingdom Protista), and eucaryotic multi-cellular and multinucleate. On each level there is divergence in relation to threeprincipal modes of nutrition-the photosynthetic, absorptive, and ingestive. Ingestivenutrition is lacking in the Monera; and the three modes are continuous along numerousevolutionary lines in the Protista; but on the multicellular-multinucleate level the nutri-tive modes lead to the widely different kinds of organization which characterize thethree higher kingdoms-Plantae, Fungi, and Animalia. Evolutionary relations are muchsimplified, particularly in the Protista. Phyla are those of Table 1; but only major animalphyla are entered, and phyla of the bacteria are omitted. The Coelenterata comprisethe Cnidaria and Ctenophora; the Tentaculata comprise the Bryozoa, Brachiopoda, andPhoronida, and in some treatments the Entoprocta.

157

closely allied to phyla of the threehigher kingdoms than to some otherphyla of the protists. Yet the kingdomProtista is definable by a level of orga-nization (eucaryotic, unicellular); where-as the higher kingdoms are defined bykinds and evolutionary directions oforganization on the multicellular-multi-nucleate level. Such horizontal andvertical classification, horizontally sepa-rating an ancestral base-taxon from theseveral taxa as evolutionary lines de-rived from it, may be preferable todividing up the intergrading members ofthe ancestral taxon and assigning themto the descendent taxa (68). The pro-tists are a complex of variously inter-connected evolutionary lines, of manyevolutionary developments in paralleland convergence, and of phyla whichhave been difficult to delimit and someof which are doubtless polyphyletic. Somuch has been learned of detailedstructure and biochemical characteris-tics which suggests relationships andpermits grouping into phyla, that wemay hope there is much more under-standing of the protists to be gainedfrom further study. The protists as akingdom have seemed monophyletic;but the implications of possible inde-pendent acquisition of symbiotic algaewhich became chloroplasts, if this proc-ess is accepted, for origin of the king-dom and its phyla are still to be ex-plored (38).

Monophyly is a principal value of sys-tematics (68, 69), but like other valuesis not absolute and will not always befollowed to the sacrifice of other ob-jectives. I have chosen to base classi-fication on three levels of organization-the procaryotic, eucaryotic unicel-lular, and multicellular-multinucleate-and three principal directions of evolu-tion related to nutrition, which on themulticellular-multinucleate level are ex-pressed in the evolutionary divergencesof the three higher kingdoms. The threehigher kingdoms are polyphyletic inparallel fashions. Each includes a domi-nant evolutionary line to higher orga-nisms as its major subkingdom, andminor subkingdoms which are indepen-dent experiments in multicellular ormultinucleate organization in one of thethree nutritive directions. In each casethese minor subkingdoms are less widelysuccessful than the principal subking-dom, represent somewhat lower anddifferent organization from it, and mayto some degree depart from the typicalnutritive mode of the kingdom.

158

Conclusion and Summary

The proposals for revised broad clas-sification are consequences of greatlyincreased knowledge of the evolutionaryrelations of organisms since the timeof the early naturalists. There is ad-vantage in considering competing sys-tems of kingdoms of organisms. Noneof these systems can be wholly satisfac-tory; but it may in time be apparentwhich one best expresses the broad re-lationships of the living world. For thepresent, the systems deserve scrutiny byprofessional biologists to assess theirmerits and the bearing on them of in-formation available or still to be sought.The new systems also have value inteaching, for the additional interest andcoherence they can give to discussionsof the diversity of life. There is no un-equivocal answer to the choice of asystem of broad classification, but thequestion is well worth discussing.The division of the whole living world

into plant and animal kingdoms is aconsequence of a limited view of thatworld, based on familiarity with higherplants and animals. The two-kingdomsystem (i) imposes an unnatural divi-sion on the one-celled organisms, (ii)does not treat adequately the place anddistinctiveness of bacteria and higherfungi, and (iii) by its neglect of greatdifferences in levels of organization pro-duces kingdoms which are nearly unde-finable.Many of these difficulties are re-

solved in the system of Copeland,with four kingdoms: Monera (pro-caryotic cells-bacteria and blue-greenalgae), Protoctista (eucaryotic orga-nisms without advanced tissue differenti-ation-unicellular and multicellularalgae, protozoa, and fungi), Metaphyta(multicellular green plants), and Meta-zoa (multicellular animals). A five-kingdom system is proposed here, basedboth on levels of organization and ontypes of organization as evolved in re-lation to three principal means of nu-trition-photosynthesis, absorption, andingestion. The kingdoms are the Mon-era, Protista (unicellular eucaryoticorganisms), Plantae (multicellulargreen plants and higher algae), Fungi(multinucleate higher fungi), and Ani-malia (multicellular animals). Revisedbroad classifications deserve wide con-sideration, for they may better expressmajor relationships in the living worldand more effectively classify the phylathan the two-kingdom system.

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68. G. G. Simpson, Amer. Mutseumn Nat. Hist.Btull. 85, 1 (1945).

69. G. G. Simpson, Principles of Animal Tax-onomy (Columbia University Press, NewYork, 1961); P. H. Davis and V. H. Hey-wood, Principles of Angiosperm Taxonomtiy(Van Nostrand, Princeton, N.J., 1963).

70. Stamm Moneres, Haeckel (29) Monera (30,31), Kingdom Monera, Copeland (1);Kingdom Mychota, G. Enderlein, Bakterien-Cyklogenie (de Gruyter, Berlin, 1925); andCopeland (2, 3).

71. Branch Myxomonera and Mastigomoneraare new designations for divisions of theKingdom Monera as indicated; the divisions(but not the designations) following E. G.Pringsheim, Bacteriol. Rev. 13, 47 (1949);Stanier (12), and Hutchinson (15). E. C.Dougherty, J. Protozool. 4 (suppl.) 14(1957) has termed these two groups phylumSchizophyta. F. Cohn, Beitr. Biol. Pflanz. 1,3, 201 (1875); R. von Wettstein, Handbuchder systematischen Botanik (Deuticke, Leipzig& Wien, 1901-1908), and phylum Archephyta(29), but the suffix -phyta seems inappro-priate for bacterial groups.

72. In addition to the Cyanophyta (= Myxo-phyta), widely accepted as a phylum, threemajor bacterial groups, the classes Eubac-teriae, Myxobacteriae, and Spirochaetae ofStanier and van Niel (7, 19) are givenphylum status. The mycelial bacteria [ac-tinomycetes as defined by Stanier et al. (19)]are regarded as also deserving phylum statusas the Actinomycota, despite the occurrenceamong them (as in certain phyla of truefungi) of nonmycelial forms and the difficul-ty of the boundary between them and thegram-positive eubacteria.

73. Kingdom Protista, Haeckel (29-32) andothers (33, 20, 5, 14); Kingdom Protozoa,Owen (27).

74. The phyla of the Protista form a spectrumfrom primarily photosynthetic (Protophyta),through primarily absorptive and spore-form-ing (which may be designated Protomycota),to primarily ingestive or otherwise animal-like (Protozoa). The evolutionary continu-ities and overlap in nutritive adaptations ofthe phyla discourage suggestion of subking-doms or branches. An intermediate treatmentof protist phyla has been sought. The algalphyla follow the pattern set by Conard (6),Tippo (62), and others (17, 60). Chadefaud(11), F. E. Round, Brit. Phycol. Bull. 2,224 (1963), and T. Christensen, Alger(Munksgaard, Copenhagen, 1962, 1966) groupthe Chrysophyta, Pyrrophyta, and Phaeophytainto the phylum (or superphylum) Chromo-phycophyta or Chromophyta, and group theEuglenophyta, Chlorophyta, and Charophytainto the phylum Chlorophycophyta or Chloro-phyta s. 1. Some other authors [C. J. Alexo-poulos and H. C. Bold, Algae and Fungi(Macmillan, New York, 1967)] divide someof the algal phyla given into additionalphyla. Despite the continuities of the Zoo-mastigina and Sarcodina with one anotherand protophyte groups, recognition of thesetwo polyphyletic form-phyla of protozoanshas been preferred to combining them withthe Chrysophytes into the very diverse groupSarcomastigophora or Rhizofiagellata (15);B. M. Honigberg et al., 1. Protozool. 11,7 (1964).

75. New designations at the level of the phylumfor class Hyphochytridiomycetes or order

Hyphochytridiales and class Plasmodiophoro-mycetes or order Plasmodiophorales.

76. Linnaeus (25); subkingdom Metaphyta,Haeckel (29-32); kingdom Phytalia, Conard(6); Plantae, Simpson (20); Whittaker (5).

77. New subkingdom designations, phylumRhodophycophyta and Phaeophycophyta,Papenfuss (61); phyla and subkingdomsRhodophyta and Phaeophyta, Whittaker (5).

78. New designation, Whittaker (5), equalsphylum Chlorophyta of Conard (6); king-dom Plantae of Copeland (1-3).

79. With the phylum Chlorophyta defined toexclude the Charophyta, the term Chloro-phycophyta, Pappenfuss (61), Chadefaud(11) [Phycophyta, Conard, (6)], has beenapplied to the branch comprising both.

80. Haeckel (29-32), narrowed in content toinclude the land plants as indicated, thusnarrowed equals Embryophyta; A. Engler,Das Pflanzenreich (Engelmann, Weinheim,1900), vol. 1; Conard (6), Tippo (62), andCormophyta; S. Endlicher. Genera plantarumsecundum ordines naturales disposita (Beck,Vienna, 1836-1840).

81. H. C. Bold, Morphology of Plants (Harper,New York, 1957), separates the liverwortsand hornworts from the Bryophyta as phylumHepatophyta.

82. Division of the tracheophytes into severalphyla is preferred by some botanists (17,81).

83. Order Fungi, C. Linnaeus, Species plantarum(Salvius, Stockholm, 1753), vol. 2; phylumFungi, Martin (42); kingdom Fungi, Jahnand Jahn (8); Whittaker (5); Regnum My-cetoideum, E. Fries, Systema mycologicum(Mauritii, Lund, 1821-32); Kingdom Myce-talia, Conard (6).

84. New designation; subkingdom Myxomycota,Whittaker (5); division Myxomycota, Bold(81); Mycetozoen, A. de Bary, Bot. Zeitung,16, 357 (1858) and Z. Wiss. Zool. 10, 88(1859>; Myxomycetes of Haeckel (29) andothers; division Myxothallophyta, Engler (80);phylum Myxomycophyta, Tippo (62).

85. New designations at phylum level for classesor orders of slime molds (56, 66, 81). Afourth group of slime molds have been de-scribed as the Protostelida [L. S. Olive,Mycologia 59, 1 (1967)]. The group multinu-from strictly unicellular to simply multinu-cleate in both vegetative and spore-formingstages; nutrition is ingestive. I interpret theseas protists most closely allied to the Gym-nomycota (in parallel with the relation ofthe hyphochytrids and plasmodiophores tothe Eumycota), best placed in phylum Sar-codina.

86. New designation, Biflagellatae of Sparrow(49), phylum Dimastigomycetes of Moreau(55).

87. Equal classes Oomycetes, Zygomycetes,Ascomycetes, and Basidiomycetes of authors;the last two are divisions Ascomycota andBasidiomycota in Bold (81).

88. New designation; group Eumycetes, A. W.Eichler, Syllabus der Vorlesungen uberspecielle und medicinisch-pharmaceutischeBotanik (Borntraeger, Berlin, ed. 4, 1886),phylum Eumycophyta, Tippo (62), and sub-kingdom Eumycota, Whittaker (5), minus theDimastigomycota.

89. The phylum or class Phycomycetes, A. deBary, Vergleichende Morphologie und Bio-logie der Pilze, Mycetozoen und Bakterien(Engelmann, Leipzig, 1884) has been dividedinto five phyla, and given new designationson this level: The primitive Hyphochytridio-mycota and Plasmodiophoromycota, trans-ferred to the kingdom Protista, the advancedZygomycota, transferred to the branch Amas-tigomycota, the intermediate Oomycota,transferred to the subkingdom Dimastigomy-cota, and the Chytridiomycota. The branchcomprising only the last of these is heredesignated the Opisthomastigomycota [Uni-flagellatae, Sparrow (49); phylum Opistho-mastigomycetes, Moreau (55); phylumOpisthokonta, Copeland (3); class Chytri-diomycetes, Alexopoulos (56)].

90. New branch designation; phylum Carpomy-cetes, Bessey (47), plus Zygomycetes; phylumInophyta, Haeckel (29), Copeland (3).

91. Linnaeus (25), Metazoa of Haeckel (29-32),and others.

92. Division of the animal kingdom follows L.H. Hyman, The Invertebrates: Protozoa

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through Ctenophora (McGraw-Hill, NewYork, 1940) in most respects. Some authors[for example, R. E. Blackwelder, Classifica-tion of the Animal Kingdom (Southern Illi-nois University, Carbondale, 1963)] dividethe Aschelminthes into several phyla andseparate additional phyla from the Arthro-poda and Chordata.

93. Branch Mesozoa, Hyman (92); branchAgnotozoa, R. C. Moore, C. G. Lalicker,A. G. Fischer, Invertebrate Fossils (McGraw-

Hill, New York, 1952); subkingdom Agno-tozoa, Moore (9).

94. Phylum Parazoa, W. 3. Sollas, Quart. J.Microscop. Sc. 24, 603 (1884).

95. W. G. KUkenthal and T. Krumbach, Hand-buch der Zoologle (de Gruyter, Berlin,1923-5).

96. Animalia radiata of G. Cuvier, Le r#gneanimal distribu6 d'apr&s son organisation(Deterville & Crochard, Paris, 1816) withnarrowed content; grade Radiata, Hyman(92); phylum Coelenterata of authors.

97. Heteraxonia or Bilateria of B. Hatschek,Lehrbuch der Zoologie (Fischer, Jena, 1888);grade Bilateria of Hyman (92).

98. W. Schimkewitsch, Biol. Zentralbl. 11, 291(1891).

99. T. H. Huxley, Quart. J. Microscop. Sci. 15,52 (1875).

100. This is a contribution from the Departmentof Population and Environmental Biology,University of California, Irvine. I thankfriends at Irvine and elsewhere for com-ments.

NEWS AND COMMENT

National Data Bank: Its AdvocatesTry To Erase "Big Brother" Image

The computer, for all its promiseand achievements as a tool of moderntechnology, is viewed with distrust bymany people who have considered itsimplications for personal privacy. Theyare uneasy at the possibility that some-day, perhaps well before 1984, therewill exist a master computer center, aBig Brother, with voluminous and in-stantly retrievable data on every Ameri-can who has lived long enough to geta social security number, a traffic ticket,or even a birth certificate, or a reportcard from school. The fact that privatecredit-rating bureaus and insurance in-vestigators already have dossiers ontens of millions of Americans itselfgives substance to these fears and isbeginning to receive attention fromCongress. However, insofar as the com-puter and personal privacy is con-cerned, the question which has receivedthe most congressional attention todate is that of whether the United Statesgovernment should establish a statisti-cal data center or "national data bank."Such a data center-first proposed in

1965 by a committee of the Social Sci-ence Research Council, a nongovern-mental group, and later endorsed by agovernment task force-would be in-tended to serve, not investigators seek-ing information about individual per-sons, but, rather, scholars and otherusers of gross statistics. One of itsprincipal aims would be to help econ-omists, other social scientists, and gov-ernment specialists investigate majoreconomic and social problems, such as

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those of persistent unemployment andsocial disorganization in the big-cityslums.A score of federal agencies, such as

the Census Bureau, the Internal Reve-nue Service, and the Social SecurityAdministration, collect data of variouskinds. The national data center wouldstore the more statistically significantdata collected by these agencies, and, asrequired for special studies, data fromtwo or more agencies would be matchedup and integrated. In a study of thecauses of poverty, for example, it mightbe useful to have census data inte-grated with data obtained from the so-cial security and internal revenue sys-tems. Most social scientists who usefederal statistics extensively probablysupport the data-bank concept, thoughthere now appears to be a general beliefthat special efforts must be made to safe-guard privacy.

Fearing that establishment of such astatistical center might lead to abuses,the House Government Operations Com-mittee's Special Subcommittee on Inva-sion of Privacy held 3 days of hear-ings on the matter, in July 1966. Thesubcommittee, headed by RepresentativeCornelius Gallagher (D-N.J.), was con-cerned at some of the testimony of gov-ernment witnesses, who said the datacenter could not integrate or update datafrom the collecting agencies withoutknowing the identities of individual per-sons.

Last August, the Gallagher subcom-mittee issued a report recommending

that the "priority of privacy" be assertedin designing and setting up the databank. The subcommittee suggested,through a series of questions, that thedata center itself keep data largely inthe aggregate and keep none on identifi-able individuals. It recommended thatthe data bank not be set up in any exist-ing federal agency, but that it be placedunder its own supervisory commissionand removed as far as possible from thepolitical pressures of an incumbent ad-ministration.

These proposed safeguards reflectedfears expressed by the subcommittee'slead-off witness, Vance Packard, authorof The Naked Society, whom Gallaghercredits with being one of the first Ameri-cans to warn that the computer posesa threat to privacy. In Packard's judg-ment there is a real danger that the ef-ficiencies attainable through assemblingmore and more data in one place mayprove irresistible, with the result that adata center designed as an innocuoustool for statisticians would become akind of electronic Frankenstein's mon-ster. "My hunch," Packard said, "is thatBig Brother, if he ever comes to theseUnited States, may turn out to be not agreedy power seeker, but rather a relent-less bureaucrat obsessed with efficiency."

Although the Nixon administrationmight conceivably decide otherwise, theoutgoing Johnson administration hasconcluded that, in view of the wide-spread mistrust of the national data bankconcept, Congress should not be askedthis year for authority to establish thedata bank. According to Raymond T.Bowman, an assistant director of theBureau of the Budget who is responsiblefor coordinating all federal statisticalservices, the administration's decisionwas to continue the interagency reviewof tentative plans for a data bank andto have those plans reviewed also by anadvisory committee, its members to bemade up of such people as constitutionallawyers, computer experts, businessmensuppliers of statistical data, and statisticsusers (Gallagher would also have the

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