ALGAE  . The Latin word alga seems to have been the See also:

• EQUIVALENT

equivalent of the See also:

• ENGLISH

English word " seaweed " and probably stood for any or all of the See also:

• SPECIES

species of See also:

• PLANTS

plants which See also:

• FORM (Lat. forma)

form the ciassltt- wrack " of a seashore . When the word " Algae " cation . came to be employed in botanical See also:

• CLASSIFICATION (Lat. classis, a class, probably from the root cal-, cla-, as in Gr. icaMce, clamor)

classification as the name of a class, an arbitrary See also:

• LIMITATION, STATUTES OF

limitation had to be set to its signification, and this was not always in keeping with its See also:

• ORIGINAL

original meaning . The See also:

• ABSENCE (Lat. absentia)

absence of differentiation into See also:

• ROOT (late O.E. rot, adopted from Scand., cf. Norw. and Swed. rot, Dan. rod; the true O.E. word was wyrt, plant, represented in Ger. Wurz or Wurzel; the ultimate root is the same in both words, and is seen in Lat. radix)
• ROOT, ELIHU (1845– )

root, See also:

• STEM (O. Eng. staefn, stemn, cf. Du. stain, Ger. Stamm, &c., probably related to " staff ")

stem and See also:

• LEAF (O. Eng. leaf, cf. Dutch loof, Ger. Laub, Swed. lof, &c.; possibly to be referred to the root seen in Gr. Ma-eta, to peel, strip)

leaf which prevails among seaweeds, seems, for example, to have led See also:

• LINNAEUS

Linnaeus to employ the See also:

• TERM

term in the Genera Plantarum for a sub-class of Cryptogamia, the members of which presented this See also:

• CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character in a greater or less degree . Of the fifteen genera included by Linnaeus among algae, not more than six—viz . See also:

• CHANT (derived through the Fr. from the Lat. cantare, to sing; an old form is " chaunt ")

Chant, Fucus, Ulva and Conferva, and in See also:

• PART

part Tremella and Byssus—would to-See also:

• DAY (O. Eng. dreg, Ger. Tag; according to the New English Dictionary, " in no way related to the Lat. dies")
• DAY, JOHN (1574-1640?)
• DAY, THOMAS (1748-1789)

day, in any sense in which the term is employed, be regarded as algae . The excluded genera are distributed among the liverworts, See also:

• LICHENS

lichens and See also:

• FUNGI (p1. of Lat. fungus, a mushroom)

fungi; but notwithstanding the See also:

• GREAT

great advance in knowledge since the See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

time of Linnaeus, the difficulty of deciding what limits to assign to the See also:

• GROUP

group to be designated Algae still remains . It arises from the fact that algae, as generally understood, do not constitute a homogeneous group, suggesting a descent from a See also:

• COMMON

common stock . Among them there exist, as will be seen hereafter, many well-marked but isolated natural See also:

• GROUPS
• GROUPS, THEORY

groups, and their inclusion in the larger group is generally See also:

• FELT (cognate with Ger. Filz, Du. vilt, Swed. and Dan. fill; the root is unknown; the word has given Med. Lat. filtrum, " filter ")

felt to be a See also:

• MATTER

matter of convenience rather than the expression of a belief in their See also:

• CLOSE
• CLOSE (from Lat. clausum, shut)
• CLOSE, MAXWELL HENRY (1822-1903)

close inter-relationship . Efforts are therefore continually being made by successive writers to exclude certain outlying sub-groups, and to reserve the term Algae for a central group reconstituted on a more natural basis within narrower limits . It is perhaps desirable, in an See also:

• ARTICLE (from Lat. articulus, a joint)

article like this, to treat of algae in the widest possible sense in which the term may be used, anindication being at the same time given of the narrower senses in which it has been proposed to employ it .

Interpreted in this way, the See also:

• PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place of algae in the See also:

• VEGETABLE

vegetable See also:

• KINGDOM

kingdom may be shown by means of a table: Cryptogamia The Vegetable See also:

• BRYOPHYTA

Bryophyta Kingdom See also:

• PTERIDOPHYTA (Gr. 1ripts, fern, and d,vrde plant)

Pteridophyta Phanerogamia I See also:

• GYMNOSPERMS

Gymnosperms See also:

• ANGIOSPERMS

Angiosperms Algae in this wide sense may be briefly described as the aggregate of those simpler forms of plant See also:

• LIFE

life usually devoid, like the See also:

• REST (O. Eng. rest, reste, bed, cognate with other Teutonic forms, e.g. Ger. Rast, Riiste, rest, and probably Gothic Rasta, league, i.e. resting or stopping place)

rest of the Thallophyta, of differentiation into root, stem and leaf; but, unlike other Thallophyta, possessed of a colouring matter; by means of which they are enabled, in the presence of sunlight, to make use of the carbonic See also:

• ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid See also:

• GAS

gas of the See also:

• ATMOSPHERE (Gr. fir µ6r, vapour; orkaipa, a sphere)

atmosphere as a source of See also:

• CARBON (symbol C, atomic weight 12)

carbon . It is true that certain Bryophyta (Marchantiaceae, Anthoceroteae) possess a thalloid structure similar to that of Thallophyta, and are at the same time possessed of the colouring matter of the See also:

• GREEN, A
• GREEN, ALEXANDER HENRY (1832—1896)
• GREEN, DUFF (1791—1875)
• GREEN, JOHN RICHARD (1837—1883)
• GREEN, MATTHEW (1696-1737)
• GREEN, THOMAS HILL (1836-1882)
• GREEN, VALENTINE (1739–1813)
• GREEN, WILLIAM HENRY (.1825–1900)

Green Algae . Their life-See also:

• CYCLE
• CYCLE (Gr. KUK)^os, a circle)

cycle, however, the structure of the reproductive See also:

• ORGANS

organs and their whole organization proclaim them to be Bryophyta (q.v.) . On the other See also:

• HAND
• HAND (a word common to Teutonic languages; cf. Ger. Hand, Goth. handus)
• HAND, FERDINAND GOTTHELF (1786-185r)

hand, certain undoubted animals (See also:

• STENTOR

Stentor, See also:

• HYDRA
• HYDRA (or SDRA, NIDRA, IDERO, &c.; anc. Hydrea)
• HYDRA (watersnake)

Hydra, Bonellia) are provided with a green colouring matter by means of which they make use of atmospheric carbonic acid . A more important See also:

• CONSIDERATION (from Lat. considerare, to look at closely, examine, generally taken to be from con-, and the base seen in sidus, sideris, a star, the word being supposed to be originally an astrological or astronomical term)

consideration is the occasional absence of this See also:

• COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour in species, ,or groups of species, with, in other respects, algal See also:

• AFFINITIES

affinities . Such aberrant forms are to be regarded in the same See also:

• LIGHT

light as Cuscuta and Orobanchaceae, for example, among Phanerogams . As these non-green plants do not cease to be classed with other Phanerogams, so must the forms in question be retained among algae . In all cases the loss of the colouring matter is associated with an incapacity to take up carbon from so See also:

• SIMPLE

simple a See also:

• COMPOUND
• COMPOUND (from Lat. componere, to combine or put together)

compound as carbonic acid . It might be mentioned here that the whole group of the Fungi (q.v.),with its many thousands of species, is now generally regarded as having been derived from algae, and the See also:

• SYSTEM

system of classification of fungi devised by Brefeld is based upon this belief . The similarity of the morphological characters of one group of fungi to those of certain algae has earned for it the name Phycomycetes or alga fungi . Further discussion of the See also:

• GENERAL
• GENERAL (Lat. generalis, of or relating to a genus, kind or class)

general characters of algae will be deferred in See also:

• ORDER
• ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
• ORDER, HOLY

order to take a brief survey of the subdivisions of the group . For this purpose there will be adopted the classification of algae into four sub-groups, founded on the nature of the colouring matters See also:

• PRESENT

present in the plant: I .

CYANOPHYCEAE, or See also:

• BLUE (common in different forms to most European languages)

Blue-green Algae . II . CHLOROPHYCEAE, or Green Algae . IV . RHODOPHYCEAE, or Red Algae . The merits and demerits of this system will appear during the description of the characters of the members of the several subdivisions . I . CYANOPHYCEAE.—ThiS group derives its name from the circumstance that the cells contain in addition to the green colouring matter, See also:

• CHLOROPHYLL (from Gr. XAwpos, green, 4bXXov, a leaf)

chlorophyll, a blue-green colouring matter to which Sub-ivisions the term phycocyanin has been applied . To the See also:

• EYE
• EYE (O. Eng. edge, Ger. Auge; derived from an Indo-European root also seen in Lat. oc-ulus, the organ of vision (q.v.)

eye, however, members of this group present a greater variety d. of colour than those of any other—yellow, See also:

• BROWN
• BROWN, CHARLES BROCKDEN (1771-181o)
• BROWN, FORD MADOX (1821-1893)
• BROWN, FRANCIS (1849- )
• BROWN, GEORGE (1818-188o)
• BROWN, HENRY KIRKE (1814-1886)
• BROWN, JACOB (1775–1828)
• BROWN, JOHN (1715–1766)
• BROWN, JOHN (1722-1787)
• BROWN, JOHN (1735–1788)
• BROWN, JOHN (1784–1858)
• BROWN, JOHN (1800-1859)
• BROWN, JOHN (1810—1882)
• BROWN, JOHN GEORGE (1831— )
• BROWN, ROBERT (1773-1858)
• BROWN, SAMUEL MORISON (1817—1856)
• BROWN, SIR GEORGE (1790-1865)
• BROWN, SIR JOHN (1816-1896)
• BROWN, SIR WILLIAM, BART
• BROWN, THOMAS (1663-1704)
• BROWN, THOMAS (1778-1820)
• BROWN, THOMAS EDWARD (1830-1897)
• BROWN, WILLIAM LAURENCE (1755–1830)

brown, See also:

• OLIVE (Olea europaea)

olive, red, See also:

• PURPLE

purple, See also:

• VIOLET

violet and See also:

• VARIATIONS
• VARIATIONS, CALCULUS
• VARIATIONS, CALCULUS OF

variations of all these being known . They undoubtedly represent the lowest grade of algal life, and their See also:

• DISTRIBUTION (Lat. distribuere, to deal out)

distribution rivals that of the Green Algae . They occur in the See also:

• SEA (in O. Eng. sae, a common Teutonic word; cf. Ger. See, Dutch Zee, &c.; the ultimate source is uncertain)
• SEA, COMMAND OF THE

sea, in fresh See also:

• WATER

water, on moist See also:

• EARTH
• EARTH (a word common to Teutonic languages, cf. Ger. Erde, Dutch aarde, Swed. and Dan. jord; outside Teutonic it appears only in the Gr. 'pq'e, on the ground; it has been connected by some etymologists with the Aryan root ar-, to plough, which is seen in
• EARTH, FIGURE OF
• EARTH, FIGURE OF THE

earth, on See also:

• DAMP

damp rocks and on the bark of trees . Certain species are regularly found in the intercellular spaces of higher plants; such are species of Nostoc in the thallus of Anthoceros, the leaves of Azolla and the roots of Cycads .

Many of them enter into the structure of the See also:

• LICHEN (lichen ruber)

lichen-thallus, as the so-called gonidia . It is remarkable that species belonging to the Oscillatoriaceae are known to flourish in hot springs, the temperature of which rises as high as 85°C . The thallus may be unicellular or multicellular . When unicellular, it may consist of isolated cells, but more commonly the cells are held together in a common jelly (Chroococcaceae) derived from the See also:

• OUTER

outer layers of the See also:

• CELL (from Lat. cella, probably from an Indo-European kal —seen in Lat. celare, to hide; another suggestion connects the word with Lat. cera, wax, taking the original meaning to refer to the honeycomb)

cell-See also:

• WALL (O. Eng. weal, weall, Mid. Eng. wal, wane, adapted from Lat. vallum, rampart; the original O. Eng. word for a wall was wag or tenth)
• WALL, RICHARD (1694-1778)

wall . The multicellular species consist of filaments, branched or unbranched, which arise by the repeated divisions of the cells in parallel planes, no formation of See also:

• MUCILAGE (from Late Lat. mucilago, a mouldy juice, from mucere, to be mouldy)

mucilage occurring in the dividing walls . Such filaments may not give rise to mucilage on the Myxomycetes Thallophyta Fungi Algae lateral See also:

• SURFACE

surface either, in which See also:

• CASE
• CASE, JOHN (d. 1600)

case they are said to be See also:

• FREE

free; when mucilage does occur on the lateral wall, it appears as the sheath surrounding either the single filament, or a sheaf of filaments of common origin . The mucilage may also form an embedding sub-stance similar to that of Chroococcaceae, in which the filaments See also:

• LIE, JONAS LAURITZ EDEMIL (1833—1908)
• LIE, MARIUS SOPHUS (1842–1899)

lie parallel or radiate from a common centre (Rivulariaceae) . The cells of the filament may be all alike, and growth may occur equally in all parts (Oscillatoriaceae) ; or certain cells (heterocysts) may become marked off by their larger See also:

• SIZE

size and the transparency of their contents; in which case growth may still be distributed equally throughout (Nostoc), or the filament may be attached where the heterocyst arises, and grow out at the opposite extremity into a See also:

• FINE

fine See also:

• HAIR (a word common to Teutonic languages)

hair (Rivulariaceae) . An See also:

• AFRICAN

African form (Camptothrix), devoid of heterocysts and hair-like at both extremities, has recently been described . Branching has been described as " false " and " true." The former arises when a filament in a sheath, either in consequence of growth in length beyond the capacity of the sheath to accommodate it, A . Gloeocapsa sp., See also:

• COLONY (Lat. colonia, from colonus, a cultivator)

colony in muci- D . Nostoc sp., See also:

• YOUNG
• YOUNG, A
• YOUNG, ARTHUR (1741-1820)
• YOUNG, BRIGHAM (1801-1877)
• YOUNG, CHARLES MAYNE (1777–1856)
• YOUNG, EDWARD (1683–1765)
• YOUNG, JAMES (1811-1883)
• YOUNG, THOMAS (1773-1829)

young colony-fila- lage .

ment with heterocysts . B . Phormidium sp., single fila- E . Scytonemasp.,false branching . ment with hormogonium . F . Rivularia sp . C . Microcoleus sp., several fila- G . Stigonema sp., with hormo- ments in common sheath . gonium and true branching . H .

Spirulina sp . (From Engler and Prantl, Pfaneenlamiiien, by permission of Wilhelm Engelman.) or because of the decay of a cell, becomes interrupted by breaking, and the free ends slip past one another . " True " branching arises only by the See also:

• LONGITUDINAL

longitudinal See also:

• DIVISION (from Lat. dividere, to break up into parts, separate)

division of a cell of a filament and the lateral outgrowth of one of the cells resulting from the division (Sirosiphonaceae) . The nature of the contents of the cells of Cyanophyceae has given rise to considerable controversy . The cells are for the most part exceedingly See also:

• MINUTE
• MINUTE (Lat. minutes, small; minuere, to make less)

minute, and are not easy to free from their colouring matters, so that investigation has been attended with great difficulty . Occupying as these algae do perhaps the lowest grade of plant life, it is a matter of See also:

• INTEREST

interest to ascertain whether a See also:

• NUCLEUS (Lat. for the kernal of a nut, nux, the stone of fruit)

nucleus or chromatophore is differentiated in their cells, or whether the functions and properties of these bodies are diffused through the whole protoplast . It is certain that the centre of the cell, which is usually non-vacuolated, is occupied by See also:

• PROTOPLASM

protoplasm of different properties from the peripheral region; and A . See also:

• FISCHER
• FISCHER, EMIL (1852– )
• FISCHER, ERNST KUNO BERTHOLD (1824–1907)

Fischer has further established the fact that the peripheral See also:

• MASS (O.E. maesse; Fr. messe; Ger. Messe; Ital. messa; from eccl. Lat. missa)
• MASS, IN

mass, which is a hollow See also:

• SPHERE (Gr. vclsa?pa, a ball or globe)

sphere in spherical cells, and either a hollow See also:

• CYLINDER (Gr. KvAwSpos, from KvXivaety, to roll)

cylinder or See also:

• BARREL (a word of uncertain origin common to Romance languages; the Celtic forms, as in the Gaelic baraill, are derived from the English)

barrel-shaped See also:

• BODY

body in filamentous forms, must be regarded as the single chromatophore of the Cyanophyceous cell . But what precisely is the nature of the central mass is still uncertain . Some investigators, such as R . Hegler, F . G .

See also:

• KOHL

Kohl and E . W . Olive, claim that this body is a true nucleus comparablewith that of the higher plants . It is said to undergo division by a mitosis essentially of the same character, with the formation of a spindle and the differentiation of chromosomes . It is further stated by Olive that the chromosomes undergo longitudinal fission, and that for the same species the same number of chromosomes appear at each division . H . See also:

• WAGER (derived, through Fr. wagier, gagier, from Lat. vadiunz, a pledge)

Wager speaks with greater reserve, acknowledging, however, the central body to be a nucleus of a rudimentary type, but devoid of nuclear membrane and nucleolus . He thinks it may possibly originate in the vacuolization of the central region, and the See also:

• ACCUMULATION (from Lat. accumulare, to heap up)

accumulation of chromatin granules therein . He finds no spindle See also:

• FIBRES
• FIBRES (or FIBERS, in American spelling; from Lat. fibra, apparently connected either with filum, thread, or findere, to split)

fibres or true chromosomes, and considers the division See also:

• DIRECT

direct, not indirect . With reference to the existence of.a chromatophore, he with others finds the colouring matter localized in granules in the peripheral region, but does not consider these individually or in the aggregate as chromatophores . Among other contents of the cell, fatty substances and See also:

• TANNIN, or TANNIC ACID

tannin are known . A curious See also:

• ADAPTATION (from Lat. adaptare. to fit to)

adaptation seems to occur in certain floating forms, in the presence of a gas-vacuole, which may be made to vary its See also:

• VOLUME

volume with varying pressure .

There is See also:

• EVIDENCE (Lat. evidentia, evideri, to appear clearly)

evidence that the dividing wall of filamentous forms is deeply pitted, as is found to be the case in red algae . See also:

• REPRODUCTION

Reproduction is chiefly effected by the vegetative method . Asexual reproductive cells are not infrequent, but sexual reproduction even in its initial stages is unknown . Nor is motility by means of See also:

• CILIA (plural of Lat. cilium, eyelash)

cilia known in the group . In the unicellular forms, cell-division involves multiplication of the plant . In all the multicellular plants of this group which have been adequately investigated, vegetative multiplication by means of what are known as hormogonia has been found to occur . These are See also:

• SHORT, FRANCIS JOB (1857– )

short segments of filaments consisting of. a few cells which disengage themselves from the See also:

• AMBIENT (from Lat. ambi, on both sides, and ire, to go)

ambient jelly, if it be present, in virtue of a See also:

• PECULIAR

peculiar creeping See also:

• MOVEMENT

movement which they possess at this See also:

• STAGE (Fr. 6/age; from Lat. stare, to stand)

stage . After a time they come to rest and give rise to new colonies, True reproduction of the asexual See also:

• KIND (O. E. ge-cynde, from the same root as is seen in " kin," supra)

kind occurs, however, in the formation of sporangia, particularly in the Chamaesiphonaceae . Here the contents of certain cells break up endogenously into a great number of spores, which are distributed as a fine dust . Resting spores are also known . In these cases, certain cells of a colony of unicellular plants or of the filaments of multicellular plants enlarge greatly and thicken their wall . When unfavourable See also:

• EXTERNAL

external conditions supervene and the See also:

• ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary cells become atrophied, these cells persist and reproduce the plant with the return of more favourable conditions .

The Oscillatoriaceae are capable of a peculiar oscillatory movement, which has earned for them their name, and which enables them to move through considerable distances . It is not clear how the movement is effected, though it has frequently been the subject of careful investigation . With the Cyanophyceae must be included, as their nearest See also:

• ALLIES, THOMAS WILLIAM (1813-1903)

allies, the Bacteriaceae (see See also:

• BACTERIOLOGY

BACTERIOLOGY) . Notwithstanding the absence of chlorophyll, and the consequent parasitic or saprophytic See also:

• HABIT (through the French from Lat. habitus, from habere, to have, hold, or, in a reflective sense, to be in a certain condition; in many of the English senses the French use habitude, not habit)

habit, Bacteriaceae agree in so many morphological features with Cyanophyceae that the See also:

• AFFINITY (Lat. affinitas, relationship by marriage, from offinis, bordering on, related to; finis, border, boundary)
• AFFINITY, CHEMICAL

affinity can hardly be doubted . A See also:

• CENSUS (from Lat. censere, to estimate or assess; connected by some with centum, i.e. a count by hundreds)

census of the Cyanophyceae with their two See also:

• MAIN (from the Aryan root which appears in " may " and " might," and Lat. magnus, great)
• MAIN (Lat. Moenus)

main groups is given below: 1 . Coccogoneae—2 families, 29 genera, 253 species . 2 . Hormogoneae—6 families, 59 genera, 701 species . (Engler and Prantl's Pflanzenfamilien, 1900.) II . CHLOROPHYCEAE.—This group includes those algae in which the green colouring matter, chlorophyll, is not accompanied by a second colouring matter, as it is in other groups . It consists of three subdivisions—Conjugatae, Euchlorophyceae and Characeae . Of these the first and last are relatively small and sharply defined families, distinguished from the second See also:

• FAMILY

family, which forms the bulk of the group, by characters so diverse that their inclusion with them in one larger group can only be justified on the ground of convenience .

Chlorophyceae include both marine and See also:

• FRESHWATER

freshwater plants . Euchlorophyceae in their turn have been until recently regarded as made up of the three See also:

• SERIES (a Latin word from serere, to join)

series of families—Protococcales, Confervales and Siphonales . As, the result of See also:

• RECENT

recent investigations by two See also:

• SWEDISH

Swedish algologists, Bohlin and See also:

• LUTHER, MARTIN (1483-1546)

Luther, it has been proposed to make a re-classification of a far-reaching nature . Algae are with-See also:

• DRAWN

drawn from each of the three series enumerated above and consolidated into an entirely new group . In these algae, the colouring matter is said to be yellowish-green, not strictly green, and contained in numerous small discoid chromatophores which are devoid of pyrenoids . The products of assimilation are stored up in the form of a fatty substance and not See also:

• STARCH

starch . A certain inequality in the character of the two cilia of the zoospores of some of the members of the group has earned for it the See also:

• TITLE (0. Fr. title, mod. titre, from Lat. titulus)

title Heterokontae, from the See also:

• GREEK
• GREEK, ETRUSCAN AND

Greek Kovros, a punting-See also:

• POLE (FAMILY)
• POLE, REGINALD (1500-1558)
• POLE, RICHARD DE LA (d. 1525)
• POLE, WILLIAM (1814—1900)

pole . In consonance with this name, its authors propose to re-name the Conjugatae Akontae and Oedogoniaceae with a chaplet of cilia become Stephanokontae, and the algae remaining over in the three series from which the Heterokontae and Stephanokontae are withdrawn become Isokontae . Conjugatae, Protococcales and Characeae are exclusively freshwater; Confervales and See also:

• SIPHON, or SYPHON (Lat. sipho; Gr. vi4xov, a tube)

Siphon-See also:

• ALES (ALEsIus), ALEXANDER (1500-1565)

ales are both freshwater and marine, but the latter group attains its greatest development in the sea . . Some Chlorophyceae are terrestrial in habit, usually growing on a damp substratum, however . Trentepohlia grows on rocks and can survive considerable See also:

• DESICCATION (from the Lat. desiccare, to dry up)

desiccation . Phycopeltis grows on the surface of leaves, Phyllobium and Phyllosiphon in their tissues .

Gomontia is a See also:

• SHELL
• SHELL (O. Eng. scell, scyll, cf. Du. sceel, shell, Goth. skalja, tile; the word means originally a thin flake,. cf. Swed. skalja, to peel off; it is allied to " scale " and " skill," from a root meaning to cleave, divide, separate)

shell-See also:

• BORING

boring alga, Dermatophyton grows on the See also:

• CARAPACE (a Fr. word, from the Span. carapacho, a shield or armour)

carapace of the See also:

• TORTOISE

tortoise and Trichophilus in the hairs of the See also:

• SLOTH

sloth . Certain Protococcales and Confervales exist as the gonidia of the lichenthallus . The thallus is of more varied structure in this group than in any other . In the simplest case it may consist of a single cell, which may remain free during the whole of the greater part of its existence, or be loosely aggregated together within a common mucilage, or be held together by the See also:

• ADHESION (from Lat. adhaerere, to adhere)

adhesion of the cell-walls at the surface of contact . These aggregations or colonies, as they are termed, may assume the form of a See also:

• PLATE

plate, a See also:

• RING (O.E. hring; a word common to Teutonic languages; and probably cognate with the Lat. circus, Gr. KtpKOS or KpLKOS, Skt'. chakra, wheel, circle, cf. also " harangue "); in art, a band of circular shape of varying sizes, made of any material and used f

ring, a solid sphere, a hollow sphere, a perforate sphere, a closed See also:

• NET

net, or a simple or branched filament . It is not easy in all cases to draw a distinction between a colony of plants and a multicellular individual . In a Volvox sphere, for example, there is a marked protoplasmic continuity between all the cells of the colony . The Ulvaceae, the thallus of which consists of laminae, one or more cells thick, or hollow tubes, probably represent a still more advanced stage in the passage of a colony into a multi-cellular plant . Here there is some amount of localization of growth and distinction of parts . It is only in such cases as Volvox and Ulvaceae that there is any pretension to the formation of a true parenchyma within the limits of the Chlorophyceae . In the whole series of the Confervales, the thallus consists of filaments branched or unbranched, attached at one extremity, and growing almost wholly at the free end . The branches end in fine hairs in Chaetophoraceae .

In Coleochaetaceae the branches are often welded into a plate, simulating a parenchyma . In all Conjugatae and most Protococcales, and in the bulk of the Confervales, the thallus consists of a cell or cells, the protoplast of which contains a single nucleus . I a H ydrodictyaceae, Cladophoraceae, Sphaeropleaceae and Gomontiaceae this is no longer the case . Instead of a single relatively large A . Chlamydomonas sp., unicellular; chr . ,chromatophore ; p.,pyrenoid; n., nucleus; p.v., pulsating vacuoles; e.s., eyespot . B1 . Volvox sp., with a, antheridia, and o, oogonia . B2 . Volvox sp., surface view of a single cell showing connexions . C . Pandorina sp., a i6-celled colony .

D . Hydrodictyon, a single mesh surrounded by 6 cells . E . Microspora sp., showing H-pieces in the wall . F . Entoderma sp., endophytic in Ectocarpus . G . Coleochaete sp., growing as a plate . H . Oedogonium sp., intercalated growth by insertion of new piece(a) leaving caps . K . Struvea sp., showing branches forming a net-See also:

• WORK

work .

L . Caulerpa sp., showing portion'of See also:

• AXIS (Lat. for " axle ")

axis with leaf-like and root-like appendages . M, . Chara sp., axis with leaf-like appendages and a See also:

• BRANCH (from the Fr. branche, late Lat. branca, an animal's paw)

branch . M2 . Chara sp., apical region . N . Botrydium, a simple siphonaceous alga with root-like See also:

• ATTACHMENT

attachment . O . Acetabularia Mediterranea, See also:

• MUSHROOM

mushroom-like calcareous siphonaceous alga . (A, C, E, F, G, H, K, L, Ms, M2 from Engler and Prantl, Pflanzenfamilien,by permission of Wilhelm Engelmann; B1, N from Vines, Students' See also:

• TEXT (Lat. textum, woven fabric, from texere, to weave)

Text See also:

• BOOK

Book of See also:

• BOTANY (from Gr. l3or6v17, plant; ,66vicety, to graze)

Botany, by permission of See also:

• SWAN (A. S. swan and swan, Icel. svanr, Du. zwaart, Ger. Schwan)
• SWAN, J
• SWAN, JOHN MACALLAN (1847-1910)
• SWAN, SIR JOSEPH WILSON (1828– )

Swan Sonnenschein and Co.; 132, D . 0 from Oltmanns, Morpholozie u .

Biologie der Algen, by permission of Gustav Fischer.) nucleus, each cell is found to contain many small nuclei, and is spoken of as a coenocyte . This character becomes still more pronounced in the large group of the Siphonales . Valoniaceae and Dasycladaceae are partially septate, but elsewhere no See also:

• CELLULOSE

cellulose partitions.occur, and the thallus is more or less the continuous See also:

• TUBE (Lat. tuba)

tube from which the group is named . Yet the siphonaceous algae may assume great variety of form and reach a high degree of differentiation . Protosiphon and Botrydium, on the one hand, are minute vesicles attached to muddy surfaces by rhizoids; Caulerpa, on the other, presents a remarkable instance of the way in which much the same external See also:

• MORPHOLOGY, (Gr. yopdsil, form)

morphology as that of cormophytes has been reached by a totally different See also:

• INTERNAL

internal. structure . Many Siphonales are encrusted with See also:

• LIME
• LIME (O. Eng. lim, Lat. limes, mud, from linere, to smear)

lime like Corallina among Red Algae . Penicillus is See also:

• BRUSH (from Fr. brosse, which, like the English word, means both the undergrowth of a wood and the instrument; if the word in both these meanings is ultimately the same, then the origin is from a bundle of brushwood used as a brush or broom, but this is h
• BRUSH, GEORGE DE FOREST (1855– )

brush-like, Halimeda and Cymopolia are jointed, Acetabularia has much the same external form as an See also:

• EXPANDED

expanded Coprinus, Neomeris simulates the fertile shoot of Equisetum with its densely packed whorled branches, and in Microdictyon, See also:

• ANADYOMENE ('AvaSvoj v )

Anadyomene, Struvea and Boodlea the branches, spreading in one "See also:

• PLANE

plane, become See also:

• BOUND, or BOUNDARY (from O. Fr. bonde, Med. Lat. bodena or butina, a frontier line)

bound together in a more or less close network . Characeae are separated from other Chlorophyceae by a See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

long See also:

• INTERVAL

interval, and present the highest degree of differentiation of parts known among Green Algae . Attached to the bottom of pools by means of rhizoids, the thallus of Characeae grows upwards by means of an apical cell, giving off whorled appendages at See also:

• REGULAR

regular intervals . The appendages have a limited growth ; but in connexion with each whorl there arise, singly or in pairs, branches which have the same unlimited growth as the main axis . There is thus a close approach to the external morphology of the higher plants . The streaming of the protoplasm, known elsewhere among Chlorophyceae, is a conspicuous feature of the cells of Characeae .

The Chlorophyceae excel all other groups of algae in the magnitude and variety of form of the chlorophyll-bodies . In Ulva and Mesocarpus the chromatophore is a single plate, which in the latter genus places its edge towards the incident light; in Spirogyra they are See also:

• SPIRAL

spiral bands embedded in the primordial utricle; in Zygnema they are a pair of stellate masses, the rays of which branch peripherally; in Oedogonium they are longitudinally-disposed anastomosing bands; in Desmids plates with irregular margins; in Cladophora polyhedral plates; in Vaucheria minute elliptical bodies occurring in immense See also:

• NUMBERS, BOOK OF
• NUMBERS, PARTITION OF

numbers . Embedded in the chromatophore, much in the same way as the nucleus is embedded in the cytoplasm, are the pyrenoids . Unknown in Cyanophyceae and Phoeophyceae, known only in Bangiaceae and Nemalion among Rhodophyceae, they are of frequent occurrence among Chlorophyceae, excepting Characeae . Sometimes several pyrenoids occur in each chloroplast, as in Mesocarpus and Spirogyra; sometimes only an occasional chloroplast contains pyrenoid at all, as in Cladophora . The pyrenoid seems to be of proteid nature and gelatinous consistency, and to arise as a new formation or by division of pre-existing pyrenoids . When carbon-assimilation is active, starch-granules See also:

• CROWD, CROUTH, CROWTH

crowd upon the surface of the pyrenoid and completely obscure it from view . See also:

• SPECIAL

Special See also:

• PROVISION (Lat. provisio)

provision for vegetative multiplication is not common among Chlorophyceae . Valonia and Caulerpa among Siphonales detach portions of their thallus, which are capable of See also:

• INDEPENDENT

independent growth . In Caulerpa no other means of multiplication is as yet known . In Characeae no fewer than four methods of vegetative reproduction have been described, and the facility with which buds and branches are in these cases detached has been adduced as an evidence of affinity with Bryophyta, which, as a class, are distinguished by their ready resort to vegetative reproduction . With regard to true reproduction, which is characterized by the formation of special cells, the group Euchlorophyceae is characterized by the See also:

• PRODUCTION (Lat. productionem, from producere, to pro-duce)

production of zoospores (Gr .

Nov, See also:

• ANIMAL
• ANIMAL (Lat. animalis, from anima, breath, soul)

animal, o,ropa, See also:

• SEED (from the root seen in Lat. serere, to sow)

seed) ; that is to say, cells capable of motility through the agency of cilia . Such ciliary See also:

• MOTION (Lat. motio, from movere, to move)
• MOTION, LAWS OF

motion is known in the adult See also:

• CONDITION (Lat. condicio, from condicere, to agree upon, arrange; not connected with conditio, from condere, conditum, to put together)

condition of the cells of Volvocaceae, but where this is not the case the reproductive cells are endowed with motility for a brief See also:

• PERIOD
• PERIOD (Gr. irepioSos, a going or way round, circuit, aepi, round, and &Sis, way, road)

period . The zoospore is usually a pyriform mass of naked protoplasm, the beaked end of which where the cilia arise is devoid of colouring matter . A reddish-brown body, known as the eyespot, is usually situated near the limits of the hyaline portion, and in the protoplasm contractile vacuoles similar to those of See also:

• LOWER

lower animals have been occasionally detected . The movement of the zoospore is effected by the lashing of the cilia and is in the direction of the See also:

• BEAK (early forms beke and becke, from Fr. bec, late Lat. beccus, supposed to be a Gaulish word; the Celtic bec and beq, however, are taken from the English)

beak, while the zoospore slowly rotates on its long axis at the same time . Usually two cilia are present; in Bolrydium and Hydrodictyon only one is present; in certain species of Cladophora four; in Dasydadus a chaplet, and in Oedogonium a ring of many cilia . The so-called zoospore of Vaucheria is a coenocyte covered over with paired cilia corresponding in position to nuclei lying below . In all other cases, zoospores are uninucleate bodies . Zoospores arise in cells of ordinary size and form termed zoosporangia . In unicellular forms (Sphaerella) the thallus becomes transformed into a zoosporangium at the reproductive stage . In the zoosporangia of Oedogonium, Tetraspora and Coleochaete the See also:

• CON

con-tents become transformed into a single zoospore . In most cases repeated division seems to take place, and the final number is re-presented by some See also:

• POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

power of two .

In coenocytic forms the zoospores would seem to arise simultaneously, probably because many nuclei are already present . The See also:

• ESCAPE (in mid. Eng. eschape or escape, from the O. Fr. eschapper, modern echapper, and escaper, low Lat. escapium, from ex, out of, and cappa, cape, cloak; cf. for the sense development the Gr. iichueoOat, literally to put off one's clothes, hence to sli

escape of zoospores is effected by the degeneration of the sporangial wall (Chaetophora), or by a See also:

• PORE

pore (Cladophora), a slit (Pediastrum), or a circular fracture (Oedogonium) . Zoospores are of two kinds: (r) Those which come to rest and germinate to form a new plant; these are asexual and are zoospores proper . (2) Those which are unable to germinate of themselves, but fuse with another cell, the product giving rise to a new individual; these are sexual and are zoogametes (Gr . Noe, animal, and yapkens, yauern, See also:

• HUSBAND

husband, wife) . When two similar zoogametes fuse, the See also:

• PROCESS

process is conjugation, and the product a zygospore (Gr . Oyav, yoke) . Usually, however, only one of the fusing cells is a zoogamete, the other gamete being a much larger resting cell . In such a case the zoogamete is male, is called an antherozoid or spermatozoid, and arises in an antheridium; the larger gamete is an oosphere and arises in an oogonium . The See also:

• FUSION

fusion is now known as fertilization, and the product is an oospore . Reproduction by conjugation is also known as isogamy, by fertilization as oogamy . When zoospores come to rest, a new cell is formed and germination ensues at once .

When zygospores and oospores are produced a new cell-wall is also formed, but a long period of rest ensues . All investigation goes to show that an essential part of sexual See also:

• UNION
• UNION (known locally as Union Hill and officially as Town of Union)

union is the fusion of the two nuclei concerned . It is interesting to know, on the authority of Oltmanns, that when the oosphere is forming in the oogonium of Vaucheria, there is a retrocession of all the included nuclei but one . That the antherozoid of Vaucheria contains a single nucleus had been inferred before . From a comparison of those Euchlorophyceae which have been most closely investigated, it appears probable that sexual reproductive cells have in the course of See also:

• EVOLUTION

evolution arisen as the result of specialization among asexual reproductive cells, and that in turn oogamous reproduction has arisen as the result of differentiation of the two conjugating cells into the smaller male gamete and the larger male gamete . It would further appear that oogamousreproduction has arisen independently in each of the three main groups of Euchlorophyceae, viz . Protococcales, Siphonales and Confervales . Thus among Volvocaceae. a family of Protococcales while in some of the genera (Chloraster, Sphondylomorum) no sexual union has as yet been observed, in others (Pandorina, Chlorogonium, Stephanosphaera, Sphaerella) conjugation of similar gametes takes place, in others still (Phacotus, Eudorina, Volvox) the union is of the nature of fertilization . No other family of Protococcales has advanced beyond the stage of isogamous reproduction . Again, among Siphon-ales only one family (Vaucheriaceae) has reached the stage of oogamy, although an incipient heterogamy is said to occur in two other families (Codiaceae, Bryopsidaceae) . Elsewhere among Siphonales, in those cases where reproductive cells are known, the reproduction is either isogamous or asexual . Among Confervales there is no family in which sexual reproduction—isogamy or oogamy—is not known to occur among some of the component species, and as many as four families (Cylindrocapsaceae, Sphaeropleaceae, Oedogoniaceae, Coleochaetaceae) are oogamous .

On these, as well as other grounds, Confervales are regarded as having attained to the highest See also:

• RANK (O.Fr. rant or rent, mod. rang, generally connected with the O.E. and O.H.G. bring, a ring)

rank among Euchlorophyceae . Although the phenomena attending isogamous and oogamous reproduction respectively are essentially the same in all cases, slight variations in both instances appear in different families, attributable doubtless to the independent origin of the process in different groups . Thus, although isogamy consists in typical cases of a union of naked motile gametes by a fusion which begins at the beaked ends, and results in the formation of an immotile spherical zygote surrounded by a cell-wall, in Leptosira it is noticeable that the fusion begins at the See also:

• BLUNT, JOHN HENRY (1823–1884)
• BLUNT, JOHN JAMES (1794–1855)
• BLUNT, WILFRID SCAWEN (184o— )

blunt end; in a species of Chlamydomonas the two gametes are each included in a cell-wall before fusion; and in many cases the zygote retains for some time its motility with the See also:

• DOUBLE
• DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Er. duble, from Lat. duplus, twice as much)

double number of cilia . Again, in oogamous reproduction, while in general only one oosphere is differentiated in the oogonium, in Sphaero plea several oospheres arise in each oogonium; and while the oospheres usually See also:

• CONTRACT
• CONTRACT (Lat. contract us, from contrahere, to draw together, to bind)

contract away from the oogonial wall, acquiring for themselves a new cell-wall after fertilization, in Coleochaete the oosphere remains throughout in contact with the oogonial wall . The oosphere is in all cases fertilized while still within the oogonium, the antherozoids being admitted by means of a pore . There is usually distinguishable upon the surface of the oosphere an See also:

• AREA

area free from chlorophyll, known as the receptive spot, at which the fusion with the antherozoid takes place; and in many cases, before fertilization, a small mucilaginous mass has been observed to See also:

• SEPARATE

separate itself off from the oosphere at this point and to escape through the pore . In Coleochaete the oogonial wall is drawn out into a considerable tube, which is provided with an apical pore, and this tube has a somewhat similar See also:

• APPEARANCE (from Lat. apparere, to appear)

appearance to the imperforate trichogyne of Florideae to be hereafter described . In certain species of Oedogonium minute male plantlets, known as See also:

• DWARF (A.S. dweorg, D. dwerg, Icel. dvergr)

dwarf See also:

• MALES

males, become attached to the See also:

• FEMALE

female plant in the See also:

• NEIGHBOUR (O. Eng. neahgebiir, from Walt, " nigh," " near ")

neighbour-See also:

• HOOD,
• HOOD, JOHN BELL (1831–1879)
• HOOD, SAMUEL HOOD, VISCOUNT (1724–1816)
• HOOD, SIR SAMUEL (1762-1814)
• HOOD, THOMAS (1799-1845)
• HOOD, TOM (1835–1874)

hood of the oogonia, thus facilitating fertilization . Indeed the genus Oedogonium exhibits a high degree of specialization in its reproductive system, considering that its thallus has not advanced beyond the stage of an unbranched filament . Many Euchlorophyceae are endowed with both asexual and sexual reproduction . Such are Coleochaete, Oedogonium, Cylindrocapsa, Ulothrix, Vaucheria, Volvox, &c . In others only the asexual method is yet known .

When a species resorts to both methods, it is generally found that the asexual method prevails in the See also:

• EARLY
• EARLY, JUBAL ANDERSON (1816-1894)

early part of the vegetative period and the sexual towards the close of that period . This is in consonance with the facts already mentioned that zoo-spores germinate forthwith, and that the sexually-produced cell or zygote enters upon a period of rest . It is known that zoogametes, which usually conjugate, may, when conjugation fails, germinate directly (Sphaerella) . In rare cases the oosphere has been known to germinate without fertilization (Oedogonium, Cylindrocapsa) . The germination of a zygospore or oospore is effected by the rupture of an outer cuticularized exosporium; then the cell may protrude an inner wall, the endosporium, and grow out into the new plant (Vaucheria), or the contents may break up into a first brood of zoospores . It is held that in Coleochaete a parenchyma results from the division of the oospore, from each cell of which a zoospore arises . Reproduction is also effected among Euchlorophyceae by means .of aplanospores and akinetes . Aplanospores would seem to represent zoospores arrested in their development; without reaching the stage of motility, they germinate within the sporangium . Akinetes are ordinary thallus cells, which on See also:

• ACCOUNT
• ACCOUNT (through O. Fr. acont, Late Lat. comptum, cornputare, to calculate)

account of their acquisition of a thick wall are capable of surviving unfavourable conditions . Both aplanospores and akinetes may germinate with or without the formation of zoospores at the initial stage . Among Conjugatae reproduction is effected solely by means of conjugation of what are literally aplanospores . Among those Desmidiaceae which live a free life, two plants become surrounded by a common mucilage, in which they lie either parallel (Closterium) or crosswise (Cosmarium) .

Gaps then appear in the apposed surfaces, usually at the See also:

• ISTHMUS (Gr.io0pbs, neck)

isthmus; the entire protoplasts either pass out to melt into one another clear of the old walls, or partly pass out and fuse without See also:

• COMPLETE

complete detachment from the old walls . Among colonial Desmidiaceae, the break-up of the filament is a preliminary to this conjugation; otherwise the process is the same . The zygospore becomes surrounded with its own wall, consisting finally of three layers, the outer of which is furnished with spicular prominences of various forms . In Zygnemaceae there is no See also:

• DISSOLUTION (from Lat. dissolvere, to break up into parts)

dissolution of the filaments, but the whole contents of one cell pass over by means of a conjugation-tube into the cavity of a cell of a neighbouring filament, where the zygospore is formed by the fusion of the two A . Spirogyra sp., in conjugation . E3 . Coleochaete sp., zoospore . B . Zoospore of Pandorina . B2 3 a, F12 3 . Protosiphon, conjugation of stages of conjugation. zoogametes . C .

Ulothrix sp., zoospores escap- G . Derbesia sp., zoospore with See also:

• ING

ing . C23, stages of con- chaplet of cilia . jugation . Ht . Chara sp., oogonium and Di . Oedogonium sp., oogonium antheridium at a See also:

• NODE (Lat. nodus, a loop)

node on at moment of fertilization a lateral appendage. with dwarf male attached . H2 . Chara sp., antherozoid . D2 . Oedogonium sp., zoospore K . Vaucheria sp., oogonium and with See also:

• CROWN

crown of cilia. antheridium before fertiliz- Et .

Coleochaete sp., with anthe- ation . ridia and an oogonium . K2 . Vaucheria sp., after fertiliza- E2 . Coleochaete sp., fertilized See also:

• EGG (O.E. aeg, cf. Ger. Ei, Swed. aegg, and prob. Gr. u,ov, Lat. ovum)
• EGG, AUGUSTUS LEOPOLD (1816-1863)

egg tion . with investment of filaments . (A from See also:

• COOKE, GEORGE FREDERICK (1756–1811)
• COOKE, JAY (1821–1905)
• COOKE, ROSE TERRY (1827-1892)

Cooke, See also:

• BRITISH

British Freshwater Algae, by permission of Kegan See also:

• PAUL
• PAUL (PAULUS)

Paul, See also:

• TRENCH, RICHARD CHENEVIX (1807-1886)

Trench, Trubner and Co.; C, E, F, G, H, K from Engler and Prantl, by permission of WilhelmEngelmann; B, from Vines, by permission of Swan Sonnenschein and Co.; B2, D from Oltmanns, by permission of Gustav Fischer.) protoplasts . In these cases the activity of one of the gametes, and the passivity of the other, is regarded as evidence of incipient See also:

• SEX (Lat. sexes; possibly connected with secure, to cut)

sex . In Sirogonium there is cell-division in the See also:

• PARENT, SIMON NAPOLEON (1855– )

parent-cell See also:

• PRIOR (from Lat. prior—former, and hence superior, through O. Fr. priour)
• PRIOR, MATTHEW (1664-1721)

prior to conjugation; and as two segments are cut off in the case of the active gamete, and only one in the case of the passive gamete, there is a corresponding difference of size, marking another step in the sexual differentiation . In Zygogonium, although no cell-division takes place, the gametes consist of a portion only of the contents of a cell, and this is regularly the case in Mesocarpaceae, which occupy the highest grade among Conjugatae . Some Zygnemaceae and Mesocarpaceae form either a short conjugating tube, or none at all, but the filaments approach each other by a See also:

• KNEE (O. E. cneow, a word common to Indo-European languages, cf. Ger. Knie, Fr. genou, Span. hinojo, Lat. genu, Gr. ybvv, Sansk. janu)

knee-like See also:

• BEND

bend, and the zygospore is formed at the point of contact, often being partially contained within the walls of the parent-cell . It would seem that in some cases the nuclei of the gametes remain distinct in the zygospore for a considerable time after conjugation .

It is probable that in all cases nuclear fusion takes place sooner or later . In Zygnemaceae and Mesocarpaceae the zygospore, after a period of rest, germinates, to form a new filamentous colony; in Desmidiaceae its contents See also:

• DIVIDE

divide on germination, and thus give rise to two or more Desmids . Gametes which fail to conjugate sometimes assume the appearance of zygospores and germinate in due course . They are known as azygospores . The reproduction of Characeae is characterized by a pronounced oogamy, the reproductive organs being the most highly differentiated among Chlorophyceae . The antheridia and oogonia are formed at the nodes of the appendages . The oogonium, seated on a stalk cell, is surrounded by an investment consisting of five spirally-See also:

• WOUND (O. Eng. wund,connected with a Teutonic verb, meaning to strive, fight, suffer, seen in O. Eng. winnan, whence Eng. " win ")

wound cells, from the projecting ends of which segments are cut off, constituting the so-called stigma . The oosphere is not differentiated within the wall of the oogonium, but certain cells known as wendungszellen, the significance of which has given rise to much See also:

• SPECULATION

speculation, are cut off from the basal portion of the parent-cell during its development . The antheridia are spherical See also:

• ORANGE
• ORANGE (Citrus Aurantium)
• ORANGE, HOUSE OF

orange-coloured bodies of very complex structure . The antherozoid is a spirally-coiled See also:

• THREAD (0. Eng. praed, literally, that which is twisted, prawan, to twist, to throw, cf. " throwster," a silk-winder, Ger. drehen, to twist, turn, Du. draad, Ger. Draht, thread, wire)

thread of protoplasm, furnished at one end with a pair of cilia . It much more resembles the antherozoids of Bryophyta and certain Pteridophyta than any known among other algae . The fertilized egg charged with See also:

• FOOD
• FOOD (like the verb " to feed," from a Teutonic root, whence O. Eng. foda; cf. " fodder "; connected with Gr. lrareicOae, to feed)

food reserves rests for a considerable period, surrounded by its cortex, the whole having assumed a reddish-brown colour .

On germination it gives rise to a See also:

• ROW, JOHN (c. 1525—1580)

row of cells in which short (nodal) and long (inter-nodal) cells alternate . From the first node arise rhizoids; from the second a lateral bud, which becomes the new plant . This peculiar product of germination, which intervenes between the oospore and the adult form, is the proembryo . It will be remembered that in M usci, the asexual spore somewhat similarly gives rise to a protonema, from which the adult plant is produced as a lateral bud . The See also:

• PRO

pro-embryonic branches of Characeae, one of the means of vegetative reproduction already referred to, are so called because they repeat the characters of the proembryo . Before leaving the Chlorophyceae, it should be mentioned that the genus Volvox has been included by some zoologists (Biitschli, for example) among See also:

• FLAGELLATA

Flagellata; on the other hand, certain green Flagellata, such as Euglena, are included by some botanists (for example, See also:

• VAN

van Tieghem) among unicellular plants . A similar uncertainty exists with reference to certain groups of Phaeophyceae, and the matter will thus arise again . A census of the Chlorophyceae is furnished below: I . Confervoideae—12 families, 77 genera, 1021 species . 2 . Siphoneae 9 families, 26 genera, 271 species . 3 .

Protococcoideae—2 families, 90 genera, 342 species . 4 . Conjugateae—2 families, 33 genera, 1296 species . (De Toni's Sylloge Algarum, 1889.) 5 . Characeae—2 families, 6 genera, 181 species . (Engler and Prantl's Pflanzenfamilien, 1897.) Euphaeophyceae are almost exclusively marine, growing on rocks and stones on the See also:

• COAST (from Lat. costa, a rib, side)

coast, or epiphytic upon other algae . In tidal seas they range from the limits of high water to some distance beyond the See also:

• LOW, SETH (1850- )
• LOW, WILL HICOK (1853- )

low-water See also:

• LINE

line . On the British coasts zones are observable in passing from high to low water See also:

• MARK
• MARK, CARL (1858– )
• MARK, GOSPEL OF ST
• MARK, ST

mark, characterized by the prevalence of different species, thus :—Pelvetia canaliculata, Fucus platycarpus, Fucus vesiculosus, Ascophyllum nodosum, Fucus serratus, Laminaria digitata . Some species are minute filamentous plants, requiring the See also:

• MICROSCOPE (Gr. µucp6s, small, asenreiv, to %view)

microscope for their detection; others, like Lessonia, are of considerable bulk, or, like Macrocystis, of enormous length . In Fucaceae, Dictyotacea, and in Laminariaceae and Sphacelariaceae, among Phaeosporeae, the thallus consists of a true parenchyma; elsewhere it consists of free filaments, or filaments so compacted together, as in Cutleriaceae and Desniarestiaceae, as to form a false parenchyma . In Fucaceae and Laminariaceae the inner See also:

• TISSUE (Fr. tissu, tissue, participle of tisser, Lat. texere, to weave)

tissue is differentiated into a conducting system . In Laminariaceae the inflation of the ends of conducting cells gives rise to the so-called outline of the oosphere have recently been described as accompanying fertilization in Halidrys .

Probably the See also:

• ACT (Lat. actus, actum)

act of fertilization in plants has nowhere been observed in such detail as in Fucaceae . Dictyotaceae resemble Fucaceae in their pronounced oogamy . They differ, however, in being also asexually reproduced . The asexual cells are immotile spores arising in fours in sporangia from superficial cells of the thallus . In Dictyota the oospheres arise singly in oogonia, crowded together in sori on the surface of the female plant . The antheridia have a similar origin and grouping on the male plant . Until the recent See also:

• DISCOVERY

discovery by See also:

• WILLIAMS
• WILLIAMS, JOHN (1582-1650)
• WILLIAMS, JOHN (1796-1839)
• WILLIAMS, ROGER (c. 1604–1684)
• WILLIAMS, ROWLAND (1817-1870)
• WILLIAMS, SIR WILLIAM FENWICK

Williams of motility, by means of a single cilium, of the antherozoids of Dictyota and Taonia, they were believed to be immotile bodies, like the male cells of red seaweeds . In Dictyota the unfertilized oosphere is found to be capable of under-going a limited number of divisions, but the body thus formed appears to See also:

• ATROPHY (Gr. It- priv., rpo4, nourishment)

atrophy sooner or later . Of the small family of the Tilopteridaceae our knowledge is as yet inadequate, but they probably present the only case of pronounced oogamy among Phaeosporeae . They are filamentous forms, exhibiting, however, a tendency to division in more than 'one plane, even in the vegetative parts . The discovery by Brebner of the specific identity of Haplospora globosa and Scaphospora speciosa marks an important step in the advance of our knowledge of the group . .Three kinds of reproductive organs are known: first, sporangia, which each give rise to a single tetra-, or multi-nucleate non-motile, probably asexual spore; second, plurilocular sporangia, which are probably antheridia, generating antherozoids; and third, sporangia, which are probably oogonia, giving rise to single uninucleate non-motile oospheres .

No process of fertilization has as yet been observed . The Cutleriaceae exhibit a heterogamy in which the female sexual cell is not highly specialized, as it is in the groups already described . From each locule of a plurilocular sporangium there is set free an oosphere, which, being furnished with a pair of cilia, swarms for a time . In similar organs on separate plants the much smaller antherozoids arise . Fertilization has been observed at See also:

• NAPLES
• NAPLES (Ital. Napoli, and Lat. Neapolis)
• NAPLES, KINGDOM OF

Naples; but it apparently depends on See also:

• CLIMATIC

climatic conditions, as at See also:

• PLYMOUTH
• PLYMOUTH, EARLS OF

Plymouth the oospheres have been observed to germinate parthenogenetically . The asexual organs in the case of Cutleria multifida arise on a crustaceous form, Aglaozonia reptans, formerly considered to be a distinct species . They are unilocular, each producing a small number of zoospores . The See also:

• POSSESSION
• POSSESSION (Lat. possessio, possidere, to possess)

possession of two kinds of reproductive organs, unilocular and plurilocular sporangia, is general among the rest of the Phaeosporeae . Bornet,however, called See also:

• ATTENTION (from Lat. ad-tendo, await, expect; the condition of being " stretched " or " tense ")

attention in 1871 to the fact that two kinds of plurilocular sporangia occurred in certain species of the genus Ectocarpus—somewhat transparent organs of an orange tint producing small zoospores, and also more opaque organs of a darker colour producing relatively larger zoospores . On the discovery of another such species by F . H . Buffham, Batters in 1892 separated the three. species, Ectocar pus See also:

• SECUNDUS, JOHANNES
• SECUNDUS, PUBLIUS POMPONIUS

secundus, E. fenestratus, E .

Lebelii, together with the new species, in& a genus, Giffordia, characterized by the possession of two kinds of plurilocular sporangia . The suspicion that a distinction of sex accompanied this difference of structure has been justified by the discovery by Sauvageau of undoubted fertilization in Giffordia secunda and G. fenestrata . The conjugation of similar gametes, arising from distinct plurilocular sporangia, was observed by Berthold in Ectocarpus siliculosus and Scytosiphon lomentarius in 188o; and these observations have been recently confirmed in the case of the former species by Sauvageau, and in the case of the latter by Kuckuck . In these cases, however, the potential gametes may, failing conjugation, germinate directly, like the zoospores derived from unilocular sporangia . The assertion of Areschoug that conjugation occurs among zoospores derived from unilocular sporangia, in the case of Dictyosiphon hippuroides, is no doubt to be ascribed to See also:

• ERROR (Lat. error, from errare, to wander, to err)

error of observation . It would thus seem that the explanation of the existence of two kinds of sporangia, unilocular and plurilocular, among Phaeosporeae, lies in the fact that unilocular sporangia are for asexual reproduction, and that plurilocular sporangia are gametangia—potential or actual . It must, however, be remembered that so important a generalization is as yet supported upon a somewhat narrow See also:

• BASE

base of observation . More-over, for the important family of the Laminariaceae only unilocular sporangia are known to occur; and for many species of other families, only one or other kind, and in some cases neither kind, has hitherto been observed . . The four species—Ectocar pus siliculosus, Giffordia secunda, Cutleria multifida and Haplospora globosa—may be taken to represent, within the Phaeosporeae, successive steps in the advance from isogamy to oogamy . The Peridiniaceae have been included among Flagellata under the title of See also:

• DINOFLAGELLATA

Dinoflagellata . The See also:

• MAJORITY (Fr. majorite; Med. Lat. majoritas; Lat. major, greater)

majority of the species belong to the sea, but many are found in fresh water . The thallus is somewhat spherical and unicellular, exhibiting a distinction between anterior and posterior extremities, .and dorsal and ventral surfaces .

The wall consists of a basis of cellulose, and in some cases readily breaks up into a definite number of plates, fitting into one another like the plates of the carapace of a tortoise; it is, moreover, often finely sculptured or coarsely ridged and flanged . Two grooves are a See also:

• CONSTANT, BENJAMIN (1845-1902)

constant feature of the family, one See also:

• RUNNING

running transversely and another longitudinally . In these grooves lie two cilia, attached at the point of See also:

• MEETING (from " to meet," to come together, assemble, 0. Eng. metals ; cf. Du. moeten, Swed. mota, Goth. gamotjan, &c., derivatives of the Teut. word for a meeting, seen in O. Eng. Wit, moot, an assembly of the people; cf. witanagemot)

meeting on the dorsal surface . The protoplast is uninucleate and vacuolate, and contains chromatophores of a brownish colour . It is not clear that 590 See also:

• TRUMPET (Fr. trompette, clairon; Ger. ,Trompete, Klarino, Trummet; Ital. tromba, trombetta, clarino)
• TRUMPET, SPEAKING AND HEARING

trumpet-hyphae . In Nereocyslis and Macrocystis a See also:

• ZONE (Gr. 'WV77, a girdle, from 'wvvLvay to gird)

zone of tubes occurs, which present the appearance of See also:

• SIEVE (O.E. sife, older sibi, cf. Dutch zeef, Ger. Sieb; from the subst. comes O.E. siftan, to sift)

sieve-tubes even. to the eventual obliteration of the perforations by a callus . While there is a general tendency in the group to mucilaginous degeneration of the cell-wall, in Laminaria digitata there are also glands secreting a plentiful mucilage . Secondary growth in thickness is effected by the tangential division of superficial cells . The most fundamental external differentiation is into holdfast and shoot . In Laminariaceae secondary cylindrical props arise obliquely from the base of the thallus . In epiphytic forms the rhizoids of the epiphyte often penetrate into the tissue of the See also:

• HOST

host, and certain epiphytes are not known to occur excepting in connexion with a certain host; but tq what extent, if any, there is a partial See also:

• PARASITISM

parasitism in these cases has not been ascertained . In filamentous forms there is a differentiation into branches of limited and branches of unlimited growth (Sphace laria) .

In Laminariaceae there is a distinction of stipe and blade . The blade is centrally-ribbed in Alaria and laterally-ribbed in Macrocystis . It is among the Sargassaceae that the greatest amount of external differentiation, rivalling that of the higher leafy plants, is reached . A characteristic feature of the more massive species is the occurrence of See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air-vesicles in their tissues . In Fucus vesiculosus they arise in lateral pai