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Rome, where he had the misfortune to be imprisoned | The fundamental form of the cell is spherical or on a charge of plundering the treasures in the castle lenticular; it is such in all young C., and is persista of St. Angelo during the siege of Rome. At length ent in those which occur in fluids, as, for example, he was liberated through the intercession of the the blood-corpuscles. Amongst other well-known Cardinal of Ferrara, for whom he executed, out of gratitude, a fine cup, and various other works. He now accompanied his deliverer to France, and entered the service of Francis I. ; but having incurred the displeasure of the ruling favourite, Madame d'Estampes, he returned to Florence-not, however, until, as usual, he had settled some matters with his

sword '—where, under the patronage of Cosmo de' Medici, he executed several fine works in metal and marble-among them, the celebrated bronze group of Perseus with the Head of Medusa,' which now decorates the market-place in Florence. Among other preserved works of C., the splendid shield in Windsor Castle may be noticed. In his 58th year, he commenced writing his autobiography, and died in 1570 or 1572.

CELLS, in Physiology.-1. ANIMAL CELLS.—On examining, under a high magnifying power, any of the constituents of the animal body, we perceive that the smallest parts which appear to the naked eye as fibres,.tubes, &c., are not ultimate elements in respect to form (morphotic elements), but that they contain, and are built up of certain extremely minute particles, which differ in different organs, but always have a similar appearance in the same organs. By far the most important of these microscopic forms, which are known by

fo histologists as simple elementary parts,' are the C., which not only form the starting-point of every animal and vegetable organism (the ovum in either kingdom of nature being simply a cell), but also either as C., or after having undergone certain

Fig. 2. modifications which will be presently described make up the tissues and organs of the perfect forms may be mentioned: a, the polygonal, as in animal. Indeed, some of the lowest plants (red pavement epithelium, or the pigment of the eye; b, snow, gory dew), and of the simplest forms of the conical or pyramidal, as in ciliated epithelium ; animal life (GREGORINÆ, &c., q. v.), appear to C, the cylindrical, as in cylinder epithelium; d, .consist of a single cell (see fig. 1).

the fusiform, or spindle-shaped, as in contractile fibre-C. ; e, the squamous, as epidermic scales; and f, the caudate, polar, or stellate, as the C. in the gray nervous tissue (see fig. 2).

With regard to size, the largest animal C.--excepting the unicellular organisms—are the yolk-C. of the ova of birds and amphibia, while the blood-C. of certain animals may be taken as representing the smallest cells. Average C. range from 0·005 to 0:01

of a line in diameter. Fig. 1.

The cell-membrane is usually transparent and

colourless, mostly smooth, and so thin as to.exhibit *a, simplest forms of independent vegetable organisms, or

unicellular plants; b, a gregorina-a unicellular animul only a single contour, rarely of any measurable organism.

thickness. No traces of structure can be detected

in it. The granular appearance which the membrane While in plants the elementary parts generally occasionally presents, is due to projections dependunite directly with one another, in animals they are ing on granules lving on the inside ; and it vanishes usually combined by an interstitial substance, which on the addition of water, which causes the cell to may be either solid or fluid, and is always derived be distended by endosmosis. See OSMOTIC ACTION. from the blood or general nutrient fluid. If this. C. which contain only fluid are rare (fat-C., interstitial substance take a part in the formation blood-C.); generally, besides fluid, they contain of the C., it is called a cytoblastema or a blastema, elementary granules and vesicles, and sometimes from kutos, a cell or vesicle, and blastema, germ-crystals. As a general rule, the number of these -substance; if it has nothing to do with their main morphotic elements increases with the age of the tenance, it is called the matrix. The cytoblastema cell; sometimes, however, this is not apparent, in is usually fluid, as in the blood, chyle, &c. ; while consequence of their being grouped in a single mass the matrix is solid, as in cartilage, bone, &c.

around the nucleus. In every cell, we can distinguish, if we use The nucleus is usually spherical or lenticular, sufficiently high magnifying powers, a membranous transparent, and either colourless or yellowish, and envelope, known as the cell-wall or membrane, and ranges from 0·002 to 0.004 of a line in diameter. certain contents. The latter are fluid or gelatinons, All nuclei are vesicles, as was originally maintained, and besides containing particles or granules, usually in 1841, by Schwann (Microscopical Researches exhibit a peculiar rounded body, the nucleus; which, into the Accordance in the Structure and Growth of again, contains in its interior a fluid and a still animals and Plants, Sydenham Society's translaomaller corpuscle, the nucleolus.

Ition, 1847, p. 173), who must be regarded as the

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founder of the cell-theory in its relation to animal endogenous. Cartilage-C. afford a good example or tissues, and as has since been confirmed by Kölliker this process. The nucleus and the contents of each and other later observers. The contents of the parent cell undergo division into two parts, so that

nucleus usually consist, the number of C. is successively doubled. This
with the exception of process is exhibited in fig. 4, where a represents
the nucleus, of a limpid
or slightly yellowish
fluid, from which water
and acetic acid precipi-
tate granular matter. In
general, only one nucleus
exists in each cell, except
when it is multiplying (a
process which we shall
presently explain); oc-
casionally, however, we
meet with several nuclei

-four, ten, or even
Fig. 3.

twenty (see fig. 3). a, cells with a single nucleus:

The nucleolus is b, a cell with two nuclei. round, sharply defined,

and often so small as to be almost immeasurable. Nucleoli are found in most nuclei so long as the latter are still young,

Fig. 4. and in many during their whole existence. As, however, nuclei exist in which no nucleolus can be

| the original cell; b, the same, beginning to divide; detected, we cannot regard the nucleolus as so essen

c, the same, shewing the complete division of the tial an element of the cell as the nucleus. Most

nucleus; d, the same, with the valves of the nucleus commonly a nucleus contains only one nucleolus;

separated, and the cavity of the cell subdivided; e, two are not unfrequently seen; more are rare.

a continuation of the same process, with cleavage

in a direction transverse to the first, so as to form a Our knowledge of the chemical composition of C. is very imperfect. That the cell-membrane is a

cluster of four C. ; and f, g, h, the production of a protein substance (q. v.)-at all events in young 10

longitudinal series of C., so as to produce filaments, C.-is obvious from its solubility in acetic acid

å by continuous cleavage in the same direction. The and in dilute caustic alkalies; and the membrane

mode in which the multiplication of the nucleus of the nucleus seems to have a similar composition; l.

on takes place cannot be definitely made out in all while there are chemical reasons for believing that ca

hot cases, but when clear observation is possible, the the nucleolus is composed of fat. In the contents

nucleoli first divide into two, and then separate. of most C. we usually find such substances as

A multiplication of C. by division has been proved occur in solution in the cytoblastema--viz., water,

to take place in the red blood-C. of the embryos albumen, fat, extractive matters, and salts; and in

of birds and mammals, and in the first colourless the C. of secreting organs, as, for instance, the

blood-C. of the tadpole, and very probably occurs liver and kidneys, we find the special secretions

extensively in many embryonic and adult tissues, of those glands; in the blood-C., we find hæmato

in which a self-multiplication of C. is certain, but crystalline, &c.

where no parent C. with secondary C. can be There are two perfectly distinct ways in which

detected. In fig. 5 are shewn the blood-C. of the C. can be generated: they may be developed independently of other C. in a plastic fluid (the cyto. blastema); or they may be developed from preexisting C. by cell-multiplication, the existing c. either producing secondary C. within themselves, or multiplying by division. In both these latter kinds of cell-development, the nucleus seems to be the centre of development of the young cells. In order that free or independent cell-develop

Fig. 5. ment shall take place, we must have a cytoblastema

Blood-corpuscles of the Chick, in the act of division. containing protein substances (probitbly fibrin), fat, and certain salts (e-pecially phosphates) in solution ; | chick dividing in this manner. In this and similar and very possibly the presence of the particles of cases we have an elongation of the cell, and the pre-existing C. may also be necessary, in which single nucleus becomes divided into two; the cell case free cell-developinent ceases to exist. The then suffers constriction in the middle, which prochyle and lymph corpuscles may be mentioned as ceeds till it finally separates into two parts, each examples of this mode of cell-formation. The steps of which contains a nucleus. This variety of cell. of the process are not very clearly made out, but formation affords a good illustration of the doubt we know that the nuclei are first formed, and that and difficulty connected with this class of investithe cell-membranes are developed around them. I gations. It was altogether unknown to Schwann Free cell-developinent is far less common in man when he published his great work in 1839, and was and the higher animals than cell-multiplication, and, first noticed and described by Remak in 1841, who, we believe, never occurs in the vegetable kingdom. however, subsequently retracted his published view, All pathological cell-formations—the C. in pus (q. v.), and did not again advocate it till Kölliker confirmed and in other morbid exudations--come, however, his observation, and declared it to be correct. under this head.

No satisfactory theory has been propounded with The development of C. within other C. is of very the view of explaining the development of cells, common occurrence. An original or parent cell Schwann compares the formation of C. with that produces two or more secondary or daughter of crystals, but it must be recollected that the C., and the process of formation is said to be molecular attraction concerned in the formation of

HO

CELLS.

C is so far peculiar, that-1. It never produces , indiscriminately; but they have the power of taking geometrical solids, but even in the nucleus and up one constituent, and rejecting another, and thus nucleolus determines a globular form; 2. That it exhibit a selective faculty. aggregates not homogeneous, but chemically differ- The cell having thus become filled from without, eut substances; and 3. That the final result of its we have next to inquire into the changes which action--namely, the cell-is extremely limited in take place in the membrane and in the contents. size, while a crystal may be of a comparatively inde- As regards the former, the membranes of most C. finite maguitude.

not only become denser and more solid with The growth of C. requires some notice. Growth age, but they undergo changes in their chemical probably occurs in all Č., although not in all to the constitution. Thus, in the horny tissues, the young same extent. It is most obvious in those which are C. are easily soluble in alkalies and acids, while formed directly round a nucleus, since in these the older C. of the same nature are scarcely affected zvembranes which at first closely invest the nucleus, by these re-agents; again, in cartilage-C., the in time become distended and enlarged, and werely membrane not only becomes firmer with age, and remain in contact with the nucleus at one point. thickens as ossification proceeds, but is changed Growth may take place either in surface or in thick- into a tissue yielding gelatine or glue on boiling, ness. The former is most commonly general-viz., which subsequently beconies impregnated with salts in all those cases where C. increase without alter- of lime (phosphate and carbonate). See BONE. ing their form; but is sometimes partial-viz., in The function of secretion is mainly carried on by those cases in which the cell deviates considerably changes in the contents of the cells. Thus, mucus from the primary globular form. The latter occurs is formed in the epithelial c. of the mucous men

to a certain degree in all C., but branes, pepsin in those of the gastric glands, bile in some kinds to a far greater in the C. of the liver, and sepia in the C. of the extent than in others. In fig. 6, link-bag of the cuttle-fish. In tbese cases, the C. two cartilage-C., magnified 350 do not separate mucus, pepsin, &c., from the blood, diameters, are shewn, in which the but merely the materials from which they elaborate walls are much thickened; in these substances. In other cases, as for instance, in addition to their nucleus, each the C. of the kidney, the function of these minute contains a clear drop of fat. The organisms is not to manufacture new products, but

nuclei and nucleoli also take part merely to separate certain substances (urea, uric Fig. 6. to a certain extent in the growth acid, &c.) from the blood, which, if not immediately

of the cells. Schwann gives the removed from the general circulation, would speedily following general explanation of the process of accumulate, and act as a deadly poison. That these growth. He considers that the molecules of the C. merely separate the urea from the blood, and do cell-membrane exert an attractive influence on the not form it in their interior, is proved by the fact fluid which surrounds them, and deposit its newly that, if the kidneys of an animal were extirpated, formed particles amongst themselves. If the depo- the urea and other urinary constituents may speedily sition take place between the molecules already be found in large quantity in the blood. present in the substance of the membrane, the cell Excretion takes place by the bursting or plution becomes distended; if it take place only in one or of the distended secreting cell, usually into the more definite directions, the membrane becomes | duct of a secreting gland. The reader who desires thickened.

further information on the functions of the C. in Having now traced the cell to the period of its relation to secretion and excretion, is especially refull growth, we are prepared to consider the ferred to an admirable memoir by Professor Goodprocesses which occur in the interior of this minute sir, ‘On Secreting Structures,' published in John and organic structure, or, in other words, the physiology Ilarry D. S. Goodsir's Anatomical and Pathological of cells. To enter satisfactorily into this subject, we | Researches, 1845. onght to have an exact knowledge of the chemical In conclusion, we must notice the metamorphoses composition of the contents of different cells. All of cells. The ovum itself is, as we have already that we know of the contents of C. generally is, as mentioned, merely a nucleated cell; after impreg. we have already stated, that they usually consist nation, a number of secondary C. are formed within of a moderately concentrated solution of protein it, by a process of cleavage or segmentation. See matters, with alkaline and earthy salts, and dissolved articles GENERATION and Ovum. Some of the C. or suspended fat-particles; and that besides these which occur in the ovum in its early stages soon ingredients many C contain either a great prepon- coalesce with others to form the higher elementarv derance of one of these constituents, to the almost parts, which we shall shortly enumerate; others, entire exclusion of others, or are found to contain without entering into combinations, more or less altogether new substances. Thus, there are C. with change their previous nature, as the horny plates much protein matters, as the nerve-C., and with of the epidermis and nails; while others, again, unmuch fåt, like the fat-C. ; while there are other C. dergo no change of form throughout the period of which specially contain hæmatine (the red colouring their existence. matter of the blood), pigment, biliary and urinary The permanent C. are arranged by Kölliker constituents, mucus, milk, sugar, &c.

|(Manual of Human Histology, translated by Busk The main cell-processes occurring in these vari- and Huxler, 1853, vol. i. p. 47) under the following ously constituted C. are absorption, secretion, and heads: excretion. These depend principally, if not entirelv, 1. True Cells, which have in no essential respect upon chemical and physical laws, and are to a great altered their cellular character. These occur in extent amenable to micro chemical observation. the epidermis and the epithelium; in the blood,

Absorption, or the appropriation of matters from chyle, and lymph; in the glandular secretions, in withont, is most manifest in those C. which at the fatty tissue, in the gray nervous substance, in first have little or no contents save the nucleus. the glands (liver, spleen, &c.), and the cartilages. Although endosmose must be taken into account as Their varieties of form and contents have been a condition of absorption, C. must not be regarded already noticed. Regarding their modes of occurmerely as vesicles provided with indifferent porous rence, some are either isolated in fluids or in solid membranes; for the filling of C. does not take tissues; others are united by apposition, without any place by their admitting every kind of matter | intervening structure, into a cellular parenchyma:

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CELLSCELLULAR TISSUE.

while others, again, are conjoined by an intercel., Both the cell-wall and the contents differ from the lular substance of some kind.

corresponding parts in animal cells. In all young C. 2. Metamorphosed Cells. To these belong-The the wall is membranous, freely permeable by water, horny scales : flattened, polygonal, or fusiform; 1 elastic, and flexible. In many cases it retains these their membrane being fused into one mass with properties, whilst in others it becomes much moditheir contents. They occur in the epidermis, the fied, as the cell grows older. It consists mainly of laminated parement epithelium, and the hair and CELLULOSE (q. v.). As the vital and chemical phenonails. The contractile fibre-C.: fusiform, slightly mena exhibited by plants depend primarily upon flattened, considerably elongated C., whose mem- operations in the interior of the cell, the careful brane, with its soft, solid contents, is changed into study of the cell contents is of the highest importa contractile substance. They occur in the smooth ance. Of these contents, the most important are or involuntary muscles. The tubules of the crystal- the primordial utricle, with the protoplasm, the line lens of the eye: very elongated C., with viscid, nucleus, chlorophyll corpuscles, and starch granules. albuminous contents. The prisms of the enamel of The primordial utricle is a layer of substance of the teeth : greatly elongated, prismatic, and strongly mucilaginous consistence (coloured yellow by iodine), calcified cells. The bone-C. : thickened C. (with lining the entire wall of the young cell, but often canaliculi, or minute branching canals) which have disappearing at a comparatively early period. The coalesced with the matrix of the bones. The trans- protoplasm is a tough mucilaginous and frequently versely striated muscular C.: large polygonal C. granular fluid, which fills up the space in the interior whose contents have become metamorphosed into a of the cell not occupied by the nucleus. The nucleus transversely striated or striped tissue, such as is or cytoblast is a globular or lenticular body, idenfound in voluntary muscular fibre. From these tical in its character with the substance of the C. are formed all the different fibres, net-works, primordial utricle, and occurring in the protoplasm membranes, tubes, &c. ; in short, all the higher of most young cells. Little is known with certainty elementary parts of which the animal body is com- regarding the chlorophyll corpuscles, except that, posed.

under the influence of solar light, green colouring For further information on C. and cell-develop- matter is developed from them. Of the starch ment, the reader is referred, in addition to the granules, which are very commonly found in the works quoted in this article, to Leydig, Lehrbuch cell contents, we need not speak, as they are suffider Histologie des Menschen und der Thiere, 1857 ; ciently described in the article STARCH. and to Frey, Histologie und Histochernie des In addition to the above organised structures, we Menschen, 1859; while he will find full details on must mention as frequent constituents of the cellmorbid cell-development (the developnient and contents, fluid colouring matters, essential and fixed growth of C. in tubercle, cancer, and other morbid oils, resins, sugar, dextrine, gum, alkaloids, and deposits) in Vogel's Pathological Anatomy of the nineral or organic salts, which are not unfrequently Human Body, translated by Day, 1847 ; and in found in a crystalline form, when they are termed Wedl's Pathological Histology, translated (for the raphides. Sydenham Society) by Busk, 1855.

1 There are two modes of cell-derelopment in the II. VEGETABLE CELLS.-In the vegetable, as in the vegetable kingdom--viz. (1.) Cell-division, where two animal kingdom, the primary form of the cell is that or more new cells fill the cavity of the parent cell, of a sphere. They are, however, interfering influ- and adhere to its membranes, appearing to divide it ences, wbich usually alter or modify the primary into compartments; and (2.) Free cell-formationform, of which the most important are, (1.) Special not to be confounded with a process of the same directions assumed in the development, in obedience name which is supposed to occur in the animal to a law regulating the structure of the tissue in kingdom-in which the whole or part of the cellwhich the cell occurs; and (2.) Obstructions to the contents become detached from the cell-wall and expansion of the cell in certain directions from the resolved into new loose C., which ultimately pressure of surrounding cells.

escape from the parent cell. The former mode The most common forins referrible to the law of universally occurs in the formation of the C. by development are, (1.) the spherical or fundamental which growth is effected; the latter occurs only in form; (2.) The cylindrical, in which there is a ten- the production of C. connected with reproduction. dency to elongation in the direction of a vertical For further information, we must refer the reader axis; and (3.) The tubular, in which there is an | to Von Mohl's Principles of the Anatomy and excess of development in the direction of the two Physiology of the Vegetable Cell, translated by Hentransverse axes.

frey, London, 1852. The secondary modifications of these forms are CEʼLLULAR TI'SSUE. This is the old term numerous. Thus, in lax tissues, the spherical form for a widely diffused animal texture, which has also may become an irregular spheroid, running out into received the names of areolar, reticula, filamentous, lobed, and even stellate forms, as may be seen in the and connective tissue. If we make a cut through pith of rushes and the stems of various aquatic the skin, and proceed to raise it, we see that it is plants. Again, in seeds, the hard part of fruits, &c., loosely connected with the subjacent parts by a soft, the mutual pressure of the C. converts the spherical filamentous, elastic substance, which, when free from into polyhedral forms, of which the dodecahedron- fat, has a white fleecy aspect. This is the tissue in giving a hexagonal section, and arising from equal question. It is also found underneath the serous and pressure in all directions is the niost common, mucous membranes which are spread over internal although cubic and many other forms occasionally surfaces, and serves to attach these membranes occur.

to the parts which they line. We likewise find it The inagnitude of the vegetable C, is very varied. lying between the muscles, the blood-vessels, nerves, In flax, the liber-cells have been found 1, or even &c., occupying the interspaces between the different { of an inch in length, and the cylindrical C. of organs, and often investing each of them with a some of the Confervæ are more than an inch long- special sheath. While it thus connects and insulates although their transverse diameter is very minute- entire organs, it at the same time performs a similar whilst, on the other hand, the spores of Fungi are function in regard to the minute parts of which each C. of a diameter of zoon of an inch. The average organ is made up. Thus, for instance, in muscular diameter of the C. in the parenchymatous tissues tissue, it enters between the fibres of the muscle, is about tóg of an inch.

1 uniting them into bundles; and similarly, it enters

CELLULAR TISSUE_CELSUS.

into glands, &c. This is termed penetrating or vessels are now known to be fomed by the cougaparenchymal cellular tissue.

tion and union of ce.ls, the distinctio: berneen vascular and cellular tissue is not generally regarded as affording a good bisis for primary divisions in the classification of plants.

CELLULOSE is the term applied to the carbohydrate, C121130010, which forms the mass of the cell-membraries of all plants. It is one of a class of compounds intimately connected in their chemical constitution, but presenting remarkable plıysical differences. Without entering into chemical details, we may mention the following points of

difference between it and the chemically allied Cellular Tissue in Muriform Cellular Tissue substances--sugar, dextrine, and starch. Sugar and a Leaf. in Wood or Bark. | dextrine are soluble in cold water, and occur in

the cell sap in solution; starch is insoluble in cold It is not only one of the most general and most water, but softens into a mucilage in boiling water, extensively distributed of the tissues, but it is land is found in granules in the cell-contents; while continuous through the whole organism, and may be C. is insoluble in cold or boiling water, and, as far as traced without interruption from any one region of is at present known, is very slightly soluble in the the body to any other. It is in consequence of this strong mineral acids, its only perfect solvent being a continuity that dropsical fluids, air, &c., effused into solution of oxide of copper in ammonia. the C. T., may spread far from the spot where they The occurrence of C. in an organism was formerly were first introduced.

regarded as a certain proof that the latter belonged On examining a fragment of this tissue, when to the vegetable kingdom. It has, however, been stretched out, we see with the naked eve that it shewn to be a constituent of the lower animals. presents the appearance of a multitude of fine, soft, | Although C. forms a large proportion of the food colourless, elastic threads, like spun glass; inter- of herbivorous animals, it is supposed to pass buixed with these are delicate films or laminæ, cross- through the intestinal canal unchanged, and not to ing one another in all directions, and leaving open contribute directly to nutrition. spaces, or areolæ; hence the name of areolar tissue. CELSUS, an Epicurean philosopher, but tinged

A small quantity of colourless transparent fluid with Platonism, lived in the 2d c. after Christ, and is always present in this tissue; when abnormally wrote, after 150 A. D., under the title Logos Alethes increased, it gives rise to the form of general dropsy (the True World), the first considerable polemic J.nown as anasarca. The microscopic characters of against Christianity. The book itself has perished; C. T. are briefly noticed in the article TISSUES, but considerable fragments have been preserved as ANIMAL.

quotations given by Origen in his answer, Contra CELLULAR TISSU E, in Botany, is any Celsum, in eight books. In the fragments—which vegetable tissue formed of cohering cells alone, and are very interesting, as shewing the views of a in which there are no vessels. It is often called heathen philosopher in regard to Christianity-C., parenchyma (Gr. something spread out), although an with wit and acuteness, but without depth or attempt has been made to restrict that term to one earnestness of thought, prefers against the new kind of it, with cells of a particular form, and terms religion charges of unphilosophicalness and blind of Greek derivation have been multiplied for other credulity; and especially endeavours to convict kinds. The cells of C. T. vary much, both in form Christians of self-contradiction in their spiritual and size (see CELLS); but particular forms and sizes doctrine contrasted with their anthropomorphic are characteristic of particular kinds or particular representations of Deity; in their religions arrogance parts of plants. The products of the vital activity | contrasted with their confession of sinfulness; and of plants are formed in the interior of cells, or by in their views of the necessity of redemption. He secretion from the inner side of their walls. Vessels also reproaches Christians with their party divisions being formed from cells, it is not easy to fix the and ever-varying opinions. With regard to his own limits between C. T. and Vascular l'issue (q. v.). positive doctrines, he speaks of evil as necessary Some kinds of plants, however, are entirely con and eternal, as an essential property of the material posed of C. T. (see next article); all consist of it in world (hyle); sin as something that can never be the earliest stages of their growth; none are at entirely removed, and least of all, through a vicaany time destitute of it. Fluids are transmitted rious sacrifice. He charges Christians with having from cell to cell, through the mass of C. T., passing wilfully altered their sacred writings. through the walls of the cells where there are no CELSUS, AULUS CORNELIUS, a Latin physician openings that can be detected by the microscope. and writer, who flourished probably in the reign of The soft and succulent parts of plants, which it Augustus. He was called the Roman Hippocrates. is the care of the gardener to cherish and increase, because he generally followed the great Father of consist chiefly of cellular tissue.

Medicine,' and introduced the Hippocratic system CELLULA'RÉS, in Botany, a designation applied among the Romans. C. wrote not only on medicine, to those plants which consist entirely of Cellular but also on rhetoric, history, philosophy, the art of Tissue (q. v.), without proper vessels of any kind. war, and agriculture. His style is succinct and clear, C., thus defined, are a sub-class of acotyledonous but full of Græcisms. The only great work of his plants, containing the orders of Lichens, Fungi, and which survives, is the De Medicinâ, which is divided Algæ. In the system of De Candolle, however, the into eight books. The portions relating to surgery name C. was given to the second grand division of are exceedingly interesting and valuable, because plants, the first being called Vasculares, and the C. has there given an account of the opinions and distinction between them being the presence or observations of the Alexandrian school of medicine. absence of vessels, the C, including all acotyledonous The first edition of the De Medicinâ appeared at or cryptogamous plants. But ferns and mosses are Florence in 1478. Co's works have been translated not destitute of vessels ; so that this system is not into several modern languages. A translation into strictly accurate with regard to them: whilst, as all English was made by Dr. Grieve, London, 1756.

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