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Darwin, and when naturalists,. being convinced by him as they had not been by the transmutationists of fifty years' earlier date, were compelled to take an entirely new view of the significance of all attempts at framing a " natural " classification. Many zoologists—prominent among them in See also:

GREAT

Great See also:

BRITAIN (Gr. Hperavuml vi7vot, Bperravia; Lat. Britannia, rarely Britannia)

Britain being Huxley—had been repelled by the See also:

AIRY, SIR GEORGE BIDDELL (1801-1892)

airy fancies and assumptions of the " philosophical " morphologists. Ciassiii-The efforts of the best minds in See also:

ZOOLOGY (from Gr. Nov, a living thing, and ?byos, theory)

zoology had been cations directed for See also:

THIRTY

thirty years or more to ascertaining based on with increased accuracy and minuteness the struc- structure, microscopic and See also:

GROSS

gross, of all possible forms of lure. animals, and not only of the adult structure but of the steps of development of that structure in the growth of each See also:

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

kind of organism from the See also:

egg to maturity. Putting aside fantastic theories, these observers endeavoured to give in their classifications a strictly See also:

OBJECTIVE, or OBJECT GLASS

objective See also:

REPRESENTATION

representation of the facts of See also:

animal structure and of the structural relationships of animals to one another capable of demonstration. The See also:

groups within groups adopted for this purpose were necessarily wanting in symmetry: the whole See also:

SYSTEM

system presented a strangely irregular See also:

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

character. From See also:

time to time efforts were made by those who believed that the Creator must have followed a symmetrical system in his See also:

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

production of animals to force one or other artificial, neatly balanced See also:

SCHEME (Lat. schema, Gr. oxfjya, figure, form, from the root axe, seen in exeiv, to have, hold, to be of such shape, form, &c.)

scheme of classification upon the zoological See also:

WORLD

world. The last of these was that of See also:

Louis See also:

Agassiz (1807-1873), who, whilst See also:

SURVEYING

surveying all previous Agassiz. classifications, propounded a scheme of his own (See also:

ESSAY, ESSAYIST (Fr. essai, Late Lat. exagium, a weighing or balance; exigere, to examine; the term in general meaning any trial or effort)

Essay on Classification, 1859), in which, as well as in the criticisms he applies to other systems, the leading notion is that sub-kingdoms, classes, orders and families have a real existence, and that it is possible to ascertain and distinguish characters which are of class value, others which are only of ordinal value, and so on, so that the classes of one sub-kingdom should on See also:

paper, and in nature actually do, correspond in relative value to those of another sub-kingdom, and the orders of any one class similarly should be so taken as to be of equal Sub-Branch 2. Vermes. Class I. ANNELIDS.

Class IV. CESTOIDEA. „ II. HELMINTHS. ,, V. ROTATORIA. „ III. TURBELLARIA. value with those of another class, and have been actually so created. The whole position was changed by the acquiescence, which became universal, in the doctrine of Darwin. That doctrine took some few years to produce its effect, but it See also:

INFLUENCE (Late Lat. influentia, from influere, to flow in)

Influence became evident at once to those who accepted See also:

Dar-of Dar- winian winism that the natural classification of animals, doctrine after which collectors and anatomists, morphologists, on taxo- philosophers and embryologists had been so See also:

long now. striving, was nothing more nor less than a genea- logical See also:

tree, with breaks and gaps of various extent in its See also:

RECORD (Lat. recordari, to recall to mind, from cor, heart or mind)

record.

The facts of the relationships of animals to one another, which had been treated as the outcome of an inscrutable See also:

law by most zoologists and glibly explained by the transcendental morphologists, were amongst the most powerful arguments in support of Darwin's, theory, since they, together with all other vital phenomena, received a sufficient explanation through it. It is to be noted that, whilst the zoological system took the See also:

FORM (Lat. forma)

form of a genealogical tree, with See also:

main See also:

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

stem and numerous diverging branches, the actual form of that tree, its See also:

LIMITATION, STATUTES OF

limitation to a certain number of branches corresponding to a limited number of divergences in structure, came to be regarded as the necessary consequence of the operation of the physico-chemical See also:

LAWS

laws of the universe, and it was recognized that the ultimate explanation of that limitation is to be found only in the constitution of See also:

MATTER

matter itself. The first naturalist to put into See also:

PRACTICAL

practical form the conse- quences of the new theory, in so far as it affected zoological See also:

HAECKEL, ERNST HEINRICH (1834- )

Haeckel. classification, was See also:

ERNST, HEINRICH WILHELM (1814–1865)

Ernst Haeckel of See also:

JENA

Jena (b. 1834), who in 1866, seven years after the publication of Darwin's Origin of See also:

SPECIES

Species, published his suggestive Generelle Morphologic. Haeckel introduced into classification a number of terms intended to indicate the branchings of a genealogical tree. The whole "system " or scheme of classification was termed a genealogical tree (Stammbaum); the main branches were termed " phyla," their branchings " sub-phyla "; the great branches of the sub-phyla were termed " cladi," and the " cladi " divided into " classes," these into sub-classes, these into legions, legions into orders, orders into sub-orders, sub- orders into tribes, tribes into families, families into genera, genera into species. Additional branchings could be indicated by similar terms where necessary. There was no See also:

ATTEMPT (Lat. adtemptare, attentare, to try)

attempt in Haeckel's use of these terms to make them exactly or more than approximately equal in significance; such attempts were clearly futile and unimportant where the purpose was the See also:

EXHIBITION

exhibition of lines of descent, and where no natural equality of groups was to be expected ex hypothesi. Haeckel's classifica- tion of 1866 was only a first attempt. In the edition of the Natiirliche Schopfungsgeschichte published in 1868 he made a great advance in his genealogical classification, since he now introduced the results of the extraordinary activity in the study of See also:

EMBRYOLOGY

embryology which followed on the publication of the Origin Schopfungsgeschichte. Haeckel himself, with his See also:

PUPIL (Lat. pupillus, orphan, minor, dim. of pupus, boy, allied to puer, from root pm- or peu-, to beget, cf. "pupa," Lat. for " doll," the name given to the stage intervening between the larval and imaginal stages in certain insects)

pupil Miklucho-Maclay, had in the meantime made studies on the growth from the egg of See also:

SPONGES

Sponges—studies which resulted in the See also:

COMPLETE

complete separation of the unicellular or equicellular Protozoa from the Sponges, hitherto confounded with them. It is this introduction of the 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 of 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-structure and cell-development which, subsequently to the See also:

ESTABLISHMENT (0. Fr. establissement, Fr. etablissement, late Norm. Fr. establishement, from O. Fr. establir, Fr. etablir, Lat. stabilire, to make stable)

establishment of Darwinism, has most profoundly modified the views of systematists, and led in See also:

CONJUNCTION (from Lat. conjungere, to join together)

conjunction with the genealogical doctrine to the greatest activity in See also:

RESEARCH (O. Fr. recerche, from recercher, re- and cercer, mod. chercher, to search; Late Lat. circare, to go round in a circle, to explore)

research—an activity which culminated in the See also:

WORK

work (1873–1882) of F.

M. See also:

Balfour, and produced the profoundest modifications in classification. HaeckePs 1868 arrangement. Zoophyta. Vermes. See also:

MOLLUSCA

Mollusca. See also:

ECHINODERMA

Echinoderma. See also:

ARTHROPODA

Arthropoda. Vertebrata. In representing pictorially the groups of the animal kingdom as the branches of a tree, it becomes obvious that a distinction may be See also:

DRAWN

drawn, not merely between the individual main branches, but further a.s to the level at which they are given off from the main stem, so that one branch or set of branches may be marked off as be-longing to an earlier or See also:

LOWER

lower level than another set of branches; and the same See also:

plan may be adopted with regard to the See also:

CARIES

caries, classes and smaller branches. The See also:

TERM

term " grade " was introduced by See also:

Ray Lankester (" Notes on Embryology and Classification," in Quart. Journ.

Micr. Sci. 1877), to indicate this giving off of branches at a higher or lower, i.e. a later or earlier, level of a main stem.' The mechanism for the statement of the genealogical relationships of the groups of the animal kingdom was thus completed. Renewed study of every See also:

GROUP

group was the result of the See also:

ACCEPTANCE (Lat. acceptare, frequentative form of accipere, to receive)

acceptance of the genealogical See also:

IDEA (Gr. Ibia, connected with i&eiv, to see; cf. Lat. species from specere, to look at)

idea and of the recognition of the importance ' See also:

Sir See also:

Edwin Ray Lankester (b. 1847) was the eldest son of Edwin Lankester (1814–1874), a physician and naturalist (F.R.S. 1845), who became well known as a scientific writer and lecturer, editor of the Quarterly See also:

Journal of Microscopical See also:

SCIENCE (Lat. scientia, from scire; to learn, know)

Science from 1853 to 1871, and from 1862, in See also:

SUCCESSION (Lat. successio, from succedere, to follow after)

succession to See also:

Thomas See also:

WAKLEY, THOMAS (1795-1862)

Wakley, See also:

CORONER

coroner for Central See also:

Middlesex. Educated at St See also:

PALL

Pall's and both at See also:

DOWNING, SIR GEORGE

Downing See also:

COLLEGE (Collegium)

College, See also:

Cambridge, and See also:

Christ See also:

Church, See also:

Oxford, E. Ray Lankester obtained the See also:

Radcliffe Travelling Fellowship at Oxford in 187o, and became a See also:

FELLOW

fellow and lecturer at See also:

Exeter College in 1872. From 1874 to 1890 he was See also:

PROFESSOR (the Latin noun formed from the verb profiteri, to declare publicly, to acknowledge, profess)

professor of zoology and See also:

COMPARATIVE

comparative See also:

anatomy at University College, See also:

LONDON

London; and from 1891 to 1898 See also:

LINACRE (or LYNAKER), THOMAS (c. 146o-1524)

Linacre professor of comparative anatomy at Oxford. From 1898 to 1907 he was director of the Natural See also:

HISTORY

History See also:

DEPARTMENT (Fr. departement, from departir, to separate into parts)

Department of the See also:

BRITISH

British Museum. He was made K.C.B. in 1907. [Ed.

E. B.]. of Species. The pre-Darwinian systematists since the time of Von See also:

Baer had attached very great importance to embryological facts, holding that the stages in an animal's development were often more significant of its true See also:

AFFINITIES

affinities than its adult structure. Von Baer had gained unanimous support for his dictum, " See also:

Die Entwickelungsgeschichte ist der wahre Lichttrager See also:

FUR (connected with O. Fr. forre, a sheath or case; so " an outer covering ")

fur Untersuchungen uber organische Korper." Thus J. Miiller's studies on the larval forms of Echinoderms and the discoveries of See also:

Vaughan See also:

Thompson were appreciated. But it was only after Darwin that the cell-theory of See also:

SCHWANN, THEODOR (1810-1882)

Schwann was extended to the embryology of the animal kingdom generally, and that the knowledge of the development of an animal became a knowledge of the way in which the millions of cells of which its See also:

BODY

body is composed take their origin by fission from a smaller number of cells, and these at last from the single egg-cell. See also:

KOLLIKER, RUDOLPH ALBERT VON (1817-1905)

Kolliker (Development of Cephalopods, 1844), Remak (Development of the See also:

FROG

Frog, 1850), and others had laid the See also:

FOUNDATIONS

foundations of this knowledge in isolated examples; but it was See also:

KOVALEVSKY, SOPHIE (1850–1891)

Kovalevsky, by his accounts of the development of Ascidians and of See also:

AMPHIOXUS, or LANCELET

Amphioxus (1866), who really made zoologists see that a strict and complete cellular embryology of animals was as necessary and feasible a See also:

FACTOR (from Lat. facere, to make or do)

factor in the comprehension of their relationships as at the beginning of the See also:

CENTURY (from Lat. centuria, a division of a hundred men)

century the coarse anatomy had been shown to be by See also:

CUVIER, GEORGES LEOPOLD CHRETIEN FREDERIC DAGOBERT, BARON (1769-1832)

Cuvier. Kovalevsky's work appeared between the See also:

DATES

dates of the Generelle Morphologic and the Protozoa. Haeckel's second See also:

PEDIGREE

pedigree is as follows: Phyla. Clades. Classes.

Archezoa.

End of Article: PTEROPODA

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