Images de page
PDF
ePub
[blocks in formation]

of Tolo. Salt is also abundant. Tin and copper speaking parts. She retired from the stage in 1874, are likewise worked.

and died at Paris, 12th February 1882. In 1883 the pop. of Celebes with adjacent islands Celestine, a mineral bearing the same relation was given as 926, 132, inclusive of 6949 Chinese and to Strontia (q.v.) that heavy spar bears to baryta. 2110 Europeans, but probably exclusive of the pop. It is essentially sulphate of strontia, SrOSOg, with of the two inner peninsulas. The Bugis (see Boni), occasional admixture of sulphate of baryta, carand Mangkassars of the south peninsula, tall, bonate of lime, oxide of iron, &c., in small proshapely, and comparatively fair, are the dominant i portions. It much resembles heavy spar, but is not native race, much disposed to trading and seafaring. quite equal to it in specific gravity ; is usually blue, The ‘Alfuros,' a collective name for the other often of a very beautiful indigo-blue; sometimes native tribes, are at a very low grade of culture. colourless, more rarely reddish or yellowish. Its Celebes was first visited in 1525 by a Portuguese crystallisation is rhombic, like that of heavy spar. expedition from the Moluccas. In 1607 the Dutch Most beautiful specimens of crystallised celestine began to trade with Celebes, and now claim the are found in Sicily. Celestine derives its name whole island, which they have divided into the from its colour. It is the source from which nitrate residencies of Macassar and Menado, a third divi. of strontia, employed in the manufacture of firesion round the north and west of the Gulf of Tolo

works, is derived. being included in the residence of the Ternate.

Celestine was the name of five popes, the first The total value of the exports in 1884 was £600,000,

of whom filled St Peter's chair in 422-432 (see of which coffee formed nearly a half; and the im.

POPE). The most notable was the Neapolitan ports in the same year, £465,714. The women of

Peter di Morrone, who after a long life of ascetic Celebes weave the sarang, or national garment, which, together with variegated mats, is largely

severities was much against his will elected pope as

Celestine V. in 1294, when he was nearly eighty exported. A 'high-road'skirts the coast of the south

years of age. He resigned his office after five peninsula from Mandale, 30 miles N. of Macassar,

months, the great refusal,' for making which he to Balang.Nifra, on the Gulf of Boni ; elsewhere

| is placed by Dante at the entrance of hell. He was are only ordinary roads and footpaths. The chief

imprisoned by his successor, Boniface VIII., and town is Macassar, with a sea-frontage of nearly 21 died in 1296. He was founder of the Celestines, miles. Menado, the capital of Minahassa district, and seat of a Dutch resident, is described as the

and was canonised in 1313. prettiest settlement in the whole of the Dutch East

Celestines, an order of hermits of St Damianus, Indies, and has a pop. of 2500. See Lahure. L'ile founded by Peter di Morrone about 1254, and conde Celebes (Paris, 1879).

firmed as a monkish order by Urban IV. in 1264

and by Gregory X. in 1274. They called themCelery (Apium), a widely distributed genus of

selves Celestines when their founder ascended the Umbelliferae. The common celery (A. graveolens)

papal chair. They follow the rule of St Benedict, is found wild in Britain and most parts of Europe, in ditches, brooks, &c., especially near the sea and

wear a white garment with black hood and scapu

lary, and live a purely contemplative life. In the in saline soils, and is acrid and uneatable. In cul. | 13th and 14th centuries the order spread rapidly tivation, however, abundant nutrition has greatly

through France, Italy, and Germany, but subsemollified its properties, and two principal forms

quently decayed, and is now almost extinct. The have arisen-one in which an abundant develop- French Celestines were secularised by order of Pope ment of parenchyma has taken place in the leaf. Pius VI. in 1776-78 ; so also were the Neapolitan stalks : the other in which it affects the root--while Celestines. these again possess their sub-yarieties. The former sort is the common celery of British gardens, where

Celibacy (from celebs, unmarried'), a state the familiar long blanched succulent stalks are

opposed to the first and strongest natural law (Gen. produced by transplanting the seedlings into richly i

i. 28), has from a variety of causes come to be remanured trenches, which are filled up as the plants !

| garded in certain religious systems as a condition grow, and finally raised into ridges over which little

: of the most sublime self-sacrifice. The perpetual more than the tops of the leaves appear; and a

celibacy of the priests of Isis, and the chastity

, of the vestal virgins, are familiar instances. But supply is thus insured throughout the whole winter. The other form is the turnip-rooted

| nowhere was this sentiment so strongly and widely

manifested as among the millions devoted to celery, or celeriac, and is now largely cultivated

the religion of Buddha. The theories of oriental on the Continent. Both forms are eaten uncooked alone, or in salads, or in soups, or as a boiled or

philosophers and the natural tendency of mystics

did not fail to influence the early Christian churches, stewed vegetable, and are pleasant and wholesome,

and led before long to the doctrine that virginity is although when used too freely or freqnently they are diuretic and aphrodisiac. Some authorities

a state in itself more excellent and more holy than identify celery, instead of the closely related Parsley i

i the married life, and to the discipline which, in the

Roman Church at least, imposed celibacy upon all (q.v.), as the Apium with which victors in the Isthmian and other games were crowned, and of

priests and sacred ministers. The Old Testament which the Greeks were also wont to twine their

is remarkably free from any tendency to exalt

| celibacy above matrimony. But although texts sepulchral garlands.

may be quoted on either side, the germs of the Celeste. MADAME, dancer, was born in Paris doctrine in question may be discovered in the New 6th August 1814 ( by her own account), more prob. Testament. "St Panl affirms it to be good for a ably three or four years earlier. A pupil at the man not to touch a woman,' and wishes that all ('onservatoire, she early showed remarkable talent. men were celibate like himself (1 Cor. vii. I, 7). She made her debut in 1827 at New York, and dur. (hrist himself speaks mysterious words in coming her residence in America married one Elliott, mendation of those who have made themselves who died early. At Liverpool in 1830 she played eunuchs for the kingdom of heaven's sake;' and Fenella in Masaniello; in 1831-33 she became the Lamb is followed on Mount Zion by 144,000 extremely popular in London. Her second visit to virgins, first-fruits unto God and unto the Lamb' America (1834-37) is said to have brought her (Rev. xiv. 1-5). £40,000. After her return she took part succes. The apostolic writings, however, while they sug. sively in the management of the Theatre Royal, gest the excellence of virginity in general, supply Liverpool, and the Adelphi and Lyceum in London. no ground for the law of clerical celibacy. In the Her imperfect English long confined her to non. I first epistle to Timothy, the deacon as well as

[merged small][ocr errors]

the keshop is told he must be the husband of children, and provided for them out of the property me wie, and rule his household and his children of the church. Avaricious princes and prelates well, and forbidding to marry' is reckoned made traffic of the concubinage of the lower clergy

ng the doctrines of devils." But a remote by levying a species of blackmail, under the name unction for the later discipline has been sought of fines, on the tacit understanding that the focaria, fue in the regulations of the Jewish priestor occupant of the priest's hearth, should not be brod The Mosaic law forbade priests to marry disturbed. At the time of the Council of Trent,

somen or barlots, and enjoined continence the Emperor Charles, in the expectation that some po all when preparing to offer sacrifice. Jerome relaxation would be made in the laws on the subare that the Christian priest should offer sacrifice ject, permitted in 1548, by the arrangement known July, and should therefore be perpetually con- as the Interim, married priests to retain their wives tanent; and Pope Siricius (385 A.D.) insists that until the council should come to a decision. The mariage was permitted to the priest of the old law Emperor Ferdinand a little later (1562) urged upon only because the sacerdotal order was then limited the same council the abrogation of celibacy. But to the tribe of Levi, but now that the tribal restric- the Catholic reaction was too strong, and the tion is removed, the license is abrogated also. council in November 1563 pronounced, If any one

The ecclesiastical legislation on celibacy was de shall say that clerks constítuted in holy orders, or veloped gradually and unequally in the several regulars who have solemnly professed chastity, are parts ot the church. In the 2d century it became a able to contract matrimony, or that, being conpions custom to make vows of chastity, and it was tracted, such matrimony is valid ... let him be thought becoming in the higher clergy to renounce anathema' matrimony : and although there are examples of It should be observed, however, that in the United bishops and priests in the first three centuries living Greek Church Rome tolerates a married clergywith their wives and begetting children, it has been i.e. a man already married may be ordained priest, cun$dently asserted that no instance can be quoted and continue to live with his wife, though conat a marriage contracted at this period after ordina- tinence is imposed upon him at certain times. It is tha. The obligations of the marriage contract the custom for the young candidate for orders to were, however, considered sacred ; and the Apostolic leave the seminary for a while to get a wife, and Canns impose the penalty of deposition on bishop, then return for ordination. If he should become priest, or deacon, who should separate from his wife a widower, he cannot of course marry again, and * under the pretence of piety." At the end of the no married priest can be made a bishop. The S and beginning of the 4th century, marriage after bishops are therefore, as a rule, taken from the ordination was prohibited by formal legislation. A monasteries. further and important step was taken in the year Since the Council of Trent, the observance of *8 by the Spanish council of Elvira, which decreed celibacy has been comparatively well maintained. that sacred ministers who were already married, This is especially true of those countries where the whold live in continence. At the Council of Micra Catholic community is mixed with or surrounded an attempt was made to impose this new rule upon by Protestant neighbours, and watched by a vigi. the whole church, but it was frustrated by the lant press. Away from the high-roads of civilisaopposition of a venerable monk, Paphnutius, him. tion, in Mexico, Brazil, and other parts, concubinage

l . celibate; and the law to this day has never has again become the rule, less openly perhaps, but

en accepted in the Eastern Church. In the West, quite as obstinately as in the middle ages. however, & series of synodal enactments and papal The moral loss or gain to the church from her dis. decrees established or renewed the more rigorous cipline in this matter is a question of controversy male But in no matter of ecclesiastical discipline which from time to time has been raised within her must the distinction between theory and practice | own communion. But the attention paid by biolobe more carefully observed. The clergy everywhere gists to the hereditary transmission of human inted the law, and resisted with considerable faculties and dispositions has recently exhibited DOREMA St Patrick, who tells us that his father. the effects of celibacy in a new light. Mr Galton end prandfather were in holy orders, when laying 'has remarked that the Roman Church has acted down rules in one of his Irish synods for the con- , as if she aimed at selecting the rudest por dart of his clergy, directs that their wives should . tion of the community to be alone the parent of keep their heads covered. In the province of future generations.' The policy which attracts men Milan, indeed, the marriage of priests continued to ' and women of gentle natures fitted for deeds of be perfectly legal. Discipline and usage varied in charity, meditation, or study to the unfruitful life daterent countries, but it may be safely said that of the cloister and the priesthood, appears from fre many centuries the celibacy of the uncloistered this point of view to be singularly unwise and ederty was little more than a pious fiction, until suicidal,' tending, as it must, though by impercep. Hildebrand, afterwards Gregory VII., by his great i tible degrees, to the deterioration of the race. To

influence and vigorous measures, secured a more the enforcing of this discipline in Spain, for ex. | sort observance of the rule.

· ample (coupled with the entting off of independent From the 19th century (first and second Lateran thinkers by the Inquisition), Mr Galton attributes roabrils ja great change took place in ecclesiastical much of the decadence of the country during the las The marriage of priests was now declared to last three centuries. In France, where the most be not only sinful but invalid. It became hence. ' promising lads of the village are successively picked formand difficult for any priest to justify his mar. | out by the parish priest for the bishop's seminary, mage on the plea that the prohibition of such the process of elimination must in the long run tell mariage was abrogated by custom, or not bind. | upon the general character of the population. In ing noder supposed exceptional circumstances. i small ('atholic communities, again, where the

Tor clerical consorts became no longer wives but priestly vocation is held in high esteem by the I carabines; and, further, the priest who went plucated classes, and where mixed marriages are

through the marriage ceremony was held to commit discountenanced, a similar result cannot fail to a tar inter crime than if he had contented himself occur. The controverial literature on the matter with simple fornication. Yet in spite of all this is abundant. The most complete treatment of the the law was to a large extent set at defiance. In subject, from the historical point of view, will be Thay uurta of Europe it was a common thing for 'found in Sacerdotal Celibacy in the Christian benefice to pass from inther to son. Influential | Church, by Henry C. Lea (Philadelphia, 1867). baboga obtained letters of legitimation for their | See also MONACHISM.

[ocr errors][merged small]

ese

Cell, a unit-mass of living matter, whether such as that of the nucleolus by Valentin (1836), rounded off by itself, as in the simplest plants or occurred in rapid succession during those years. animals and in the youngest stage of all organisms, Dujardin in 1835 described the sarcode or living or associated with other cells to form a higher matter of the Protozoan Foraminifera and of some unity. The great majority of the Protozoa and other cells, and thus emphasised, as Rösel von Protophyta are single cells, and all other organisms Rosenhof had done many years before (1755) in begin where the former leave off. From the double regard to the Proteus animalcule' or Amaba, the unity resulting from the fusion of two sex-cells the most important element to be considered in formhigher plants and animals develop by repeated ing a true conception of the cell. The importance division, and they may be therefore always resolved | of his description, of which he was apparently himinto more or less close combinations of variously self unconscious, had for some time the same fate

as that of his predecessor of almost a century before. Observations had in fact to accumulate before any generalisation became possible. The first definite steps towards a co-ordination of results was probably that of Johannes Müller, who in 1835 pointed out the resemblance between the cells of the vertebrate notochord and the elements

observed in plants. The cellular nature of the Fig. 1.- Dividing Egg-cell (after Gegenbaur). epidermis and the presence of nuclei therein was

next ascertained, and similar discoveries were made modified unit-masses. In most cases these in ) in regard to several other tissues. Up to 1838 dividualities of the simplest order are minute, and there was in fact a period of research in which cells their separateness is not to be discerned with the were observed rather than understood. unaided eye, but there are many instances among Establishment of the Cell-theory.--As early as the simplest plants and animals, as well as in the 1826 Turpin had maintained that plants were component elements of higher forms, where the formed by an agglomeration of cells. Professor unit-masses are relatively giant-cells and quite M.Kendrick well points out, what one would of visible without the use of the microscope. The course expect, that for some years before 1838 giant Amoeba Pelomyxa, the common 'sun-ani. botanists were beginning generally to recognise malcule Actinosphærium, the Alga Botrydium, the cellular composition and origin of plants. The and some of the cells (e.g. bast) of plants may be conclusion known as the cell-theory' was doubtnoted as illustrations of cells with considerable less vaguely present in many minds. Its definite dimensions. In the great majority of cases the statement was still awanting. In 1838, however, body of the cell includes a well-defined centre or Schleiden proved that a nucleated cell is the only nucleus; and the definition may therefore be original component of a plant embryo, and that the extended in the statement that a cell is a nucleated development of all tissues might be referred to such unit-mass of living matter or protoplasm.

| cells. In the following year Schwann published I. History.--In the article BIOLOGY it has been at Berlin his famous Microscopic Inrestigations on pointed out that a more and more penetrating the Accordance in the Structure and Growth of scrutiny alike of structure and of function led Plants and Animals (Trans. Sydenham Society, naturalists from organs to tissues, and from tissue 1847). In this classic work it was shown that all to cell. Some of the steps in this gradually organisms, plants and animals alike, are made up deepening analysis deserve fuller record.

of cells, and spring from cells. In composition and Discovery of Cells.- In the latter half of the 17th in origin there is unity. The generalisation century the simple microscope afforded to Malpighi familiarly known as the cell-theory was thus and Leeuwenhoek, to Hooke and Grew, what clearly established, and though now a commonwas literally a vision of a new world. In place and postulate of histology, it may fairly be applying their rough and simple instruments to the described in Agassiz's words as the greatest disstudy of the structure of plants and animals they covery in the natural sciences in modern times became pioneers in the investigation of the infinitely Following up the generalisations of Schwann and little. Leeuwenhoek (Phil. Trans. 1674) seems to Schleiden, come a host of researches by which the have been the first to observe, what are now so essential advance contained in the cell theory' was familiar, single-celled organisms. In the 18th cen. more and more fully confirmed. Cells were not tury Swammerdam and others continued with much only observed, their import was recognised. enthusiasm to describe the minute intricacies Neu Conception of the l'ell.- When the cell theory which their new eyes' revealed; Fontana (1784) was established, the general conception of the celi observed the kernel of the cell-the nucleus-and was far from being either accurate or complete. It some of the elements of the tissues; but the founda was usually described as a vesicle closed by a solid tion of scientific histology was not laid until the membrane, containing a liquid in which float a appearance in 1801 of the Anatomie Générale of nucleus and granular bodies. It was also the Bichat. In this epoch-making work organs were general opinion that such cells originated within a resolved into their component tissues, and their structureless ground substance. In two ways functions were interpreted as the sum-total of the these notions were speedily corrected. On the one properties of their constituent elements. Such a hand as regards the origin of cells, Prevost and conclusion was the utmost that could be reached Dumas (1824), Martin Barry (1838-9), Reichert with the appliances then at command,

(1840), Henle (1841), Kölliker (1846), Remak (1852), Early in this century, however, an improvement showed that in the case of the egy-cell, and in the in the appliances of observation furnished a fulcrum growth of tissues, each new cell arose by division for a new advance. Fraunhofer discovered the from a predecessor. This important conclusion principle of achromatic lenses (see LENS, MICRO. was most firmly established by Goodsir in 1845, SCOPE); these were combined into the compound and Virchow in 1858, who proved that in all cases, microscope, and a new era began. Fibres and normal and pathological alike, cells arose from pre

globules, lamina,' nuclei,' and even 'cells' existing cells, a fact expressed in the axiom omnis were described. In 1831 Robert Brown emphasised cellula « rellula. In the second place it gradually the normal presence of the nucleus discovered by became apparent that too much importance had Fontana, and made the first important advances in been attached to the cell wall and too little to the the study of the vegetable cell. Isolated discoveries, I contained substance. Referring details to the CELL

article PROTOPLASM, we may note some of the (6) General Substance of the Cell.-The cell is important steps. Dujardin (1835) described the much more than a mass of highly complex chemical narcode of Protozoa and other cells; Purkinje substance : it has an organised structure. (1) The ISO) emphasised the analogy between the protoplasm or living matter in the strictest sense *protoplasın' of the animal embryo and the is generally supposed to be an intimate mixture of

cambium of plant-cells ; Von Mohl (1846) em complex and highly unstable chemical compounds. phasised in the clearest way the importance of the Inspection under à microscope of such cells as protoplasm in the vegetable cell ; Ecker (1849) amabæ, white blood-corpuscles, ova, simple algae, cotnpared the contractile substance of muscles with or such as are readily seen in thin slices of growing that of the amoeba ; Donders also referred the con- | plant-shoots, in root-hairs, and transparent parts, tractility from the cell-wall to the contained will at once furnish an impression of the general material: Cohn suspected that the 'sarcode' of aspect of the substance of the cell. Not all that animal and the protoplasm of plant-cells must be one sees can of course deserve the name of proto

in the highest degree analogous substance;' and plasm, for apart from definite inclosures like starchw throughout another decade did botanists and grains and fat-globules, much of the remaining mologists unite in laying stress rather on the slightly clouded substance is hardly to be strictly living matter than on the wall of the cell, and in called 'protoplasm, but rather represents steps in hunting at the existence of one living substance as the ceaseless making and unmaking which form the physical basis alike of plants and animals. the fundamental rhythm of life. Keeping the This view found at length definite expression in definite inclosures and products for the moment 11, when Max Schultze defined the modern con- aside, we may briefly notice in general outline trption of the cell as a unit-mass of nucleated what has been with most conclusiveness observed protoplasm. Since then the protoplasmic move as to the structure of the general cell-substance or ment has dominated research, and we think not cytoplasm' as it is now frequently termed. All so much of the cell-containing protoplasm as of the observers agree that the structure is far removed protoplasın which constitutes and gives form to the from the homogeneous, though there is much dif. cell

ference of opinion as to the nature of the heteroIL Structure of the Cell.-While it is impossible geneity. In a large number of cases at least the to isolate the static from the dynamic aspects of substance of the cell has been resolved into two the cell, it will be convenient to discuss the two distinct portions--the one an intricate network,

parately, and to consider the cell at rest and knotted and interlaced in a manner baffling descripdral, apart from the cell active and alive. In tion; the other a clear substance, filling up the other words, the form, structure, or morphology interstices or meshes of the living net. Leydig, may be studied for literary clearness apart from the Frommann, and Heitzmann have been peculiarly functions, life, and physiology.

successful in unravelling this knotted structure in far General Form. The typical and primitive animal cells, and much the same has been recorded form of the cell is spherical. This is illustrated by by Strasburger and Schmitz as observable in some many of the simplest plants and animals which live plants. The reticulate structure is certainly more freely, and by young cells such as ova. But the doubtful in regard to vegetable cells, and even in typical form is in many, indeed in most cases, lost;' some animal cells what some have described as a and the forms assumed are as diverse as the network others have deemed only a minutely internal and external conditions of life. The cell , bubbled emulsion. may be irregular and protean, as in Amoebar, white But besides the real substance of the cell there blood-corpuscles, and many young eggs; or are to be seen products of various kinds formed wueezed into rectangular shape, as in much of the from the living matter. The cell may be packed substance of a leaf; or flattened into thinness, as in with starch, or laden with fat, or expanded with the outer lining of the lips; or oval and pointed, as mucus; it may contain colouring matter in various in swiftly moving Infusorians and Bacteria ; or forms, as in the familiar chlorophyll bodies of many morb branched, as in multipolar ganglion cells of plant-cells; its structure may include, as in some animals or the latex-containing cells of some plants. · Protozoa, definitely formed fibrils or yet firmer forThe typical spherical and self-contained form is mations of chitin and the like; and again there are that which would naturally be assumed by a com- ' concretions of retained waste and reserve products, plex coherent substance situated in a medium sometimes in the form of crystals. Not to be over. different from itself. The other forms are responses looked either is the fine dust-cloud' of minute to internal and external conditions. Under the granules which are seen suspended in the clearer broting Cell-rule below it will be shown how the matrix, and which apparently represent aggregarelative activity and passivity of the cell naturally tions of diverse chemical substances formed in the expresses itself in such extremes as a long-drawn building up and breaking down of the protoplasm. mai Infusorian and a rounded-off Gregarine, or in a As the outside of any mass is bound to be in differhighly nourished ovam and a mobile spermatozoon, ent conditions from the inside, it is natural to find Further, cells like entire animals, often show a the appearance of distinct physical and chemical tendency to become two-ended, to have poles very zones in the cell-substance. Thus in many Protozoa different from one another. Just as an animal may ! the outer portion, needlessly termed ectoplasm,' is have highly nourished head and a scantily often denser and more retractive than the more tomarished tail, so a cell may become distinctly fluid and internal stratum of the endoplasm. Or bipolar in form. In other cases the cell is altogether, this may go further, and we may have a sweated. plastie, expressing every impulse of internal change off limiting cuticle, or a definitely organised wall and every impact of external influence in some of cellulose in vegetable cells. The cuticle may Bolification of form. Or the state of nutrition of be further substantiated with secretions of horny, the living matter may cause alteration in the Hinty, limy, and other material. Even within whesion of the substance all over, or in particular the cell a stratified structure may be frequently places, and thus condition an outflowing, regular observed, and Berthold and others have recently or irregular, in given directions. Furthermore, ex emphasised the existence of such concentric layers, ternal pressure and limitation of growth may each characterised by its own special set of de

are off the cell into a parallelogram, or restrict posits. it to grow like a bast fibre in length alone and not Worthy of notice, too, are the various kinds of in brewith. In fact the conditions are most mani. bubbles or vacuole which occur in the cell.sob. fold, and the resultant forms likewise.

stance. These may be simply indefinite spaces,

[ocr errors][merged small]

containing some liquid not protoplasm, and includ. and active nature. In accordance with the growth ing salts and other substances in solution. In many of the cell it may occupy a position distinctly Protozoa they are 'food-vacuoles,' formed by the nearer one of the poles. Accumulations of fat or

mucus may push it passively to the side. Or it may actively change, in response to hidden forces of attraction between it and the surrounding protoplasm, in the case of some ova exhibiting a peculiar rotation, or else distinctly shifting its ground from the centre towards the periphery.

Structure.-In many cases, as Leydig especially has shown, the nucleus seems to lie in a nest of its

own, in a clear, space within the surrounding cell. Fig. 2.

substance. Nor is it in many cases at least deA, Embryonic cells from growing point of a root; B, older cells finitely insulated from the surrounding protoplasm, becoming vacuolated. (After Sachs.)

but is moored to the latter by strands which have

intimate relations with both. As of the entire cell, bubbles of water engulfed along with the food so of the nucleus it must be said that in the great particles, round which the protoplasm, shrinking majority of cases it is very far from being homofrom contact, often forms a definite contour. In geneous. According to Hertwig, Schleicher, Schmitz, other cases they are more permanent, and represent | Brass, and others, homogeneous nuclei may indeed minute reservoirs of secreted substance, cisterns of occur, but if they do they are rare, and it must by-products in the vital manufacture of the cell. always be remembered that the nucleus has its Finally they may be seats of special activity, where, history, and may be less complex at one time than perhaps, under the stimulus of irritant waste-pro- it is at another. To Flemming (1882) above all is ducts, the protoplasm exhibits spasmodic contrac. due the credit of having elucidated the complexity tions and expansions, and forms the so-called .con- of the nucleus, and the labyrinthine structure to tractile vacuoles,' which in alternate dilatation and which he showed the clue, and to which Frommann bursting often seem to serve to remove fluid from | (1867) had many years previously directed special the living matter to the exterior.

attention, has been studied and restudied by scores (c) Nucleus.-In the great majority of cells a of expert histologists during the last six years central body of definite composition and structure (1888). While their results disagree abundantly is present which appears to be essential to the life on minor points, two conclusions stand out clearly and reproduction of the unit-mass. In many cases -(1) that the nucleus has a structure like that of the nucleus is well concealed, but as more skilful the general cell, consisting of firmer framework staining has revealed its presence in many cells and of more fluid intermediate substance, and (2) which used to be described as non-nucleated, it is that apart from detailed difference there is throughrash to conclude too certainly as to its absence in out the world of cells a marvellous unity of strucany particular case. Thus some of the Monera, ture and process, in the nucleus in repose and in which were formerly defined as the simplest of the nucleus in action. simple animal organisms without even a nuclei, In the nucleus the following parts have to be dishave been shown to possess them, and the line of tinguished: (1) The readily stained firmer threaddivision separating Protozoa into Monera and work, (2) an intermediate clear substance filling Endoplastica has therefore been removed. Fur up the interstices, (3) definite and usually globular thermore, the researches of Gruber have shown that formations known as nucleoli, (4) various granules, in some of the higher Protozoa (ciliated Infusorians) and (5) a limiting membrane or nuclear wall. where the nucleus seems entirely absent, dex. These may be briefly touched upon in order. terous staining prove its diffused presence in (1) The Nuclear Framework (reticulum, trabecu. the form of numerous granules which take on the lar framework, &c.).- A mere statement of the characteristic nuclear dye. Yet in some cases, different descriptions given of this important part such as the young spores of some Protozoa, of the nucleus would carry us far beyond the limits the greatest care has not yet been successful in of this article. The most marked difference of proving the presence of the nucleus. In contrast opinion is this, that some describe the framework with these cases, many cells exist in which the as distinctly of the nature of a network, while nucleus is represented not by one, but by many others are as emphatic in calling it a much-coiled bodies—the so-called polynuclear state. A further band. A third party unite both views, and rereserve requires to be made, that it is to a large garding the nucleus as variable, describe a reti. extent an hypothesis that all such definite central culum at one time and a coiled filament at another. inclosures should be slumped together under the Thus, according to Flemming, Pfitzner, Retzius, one title of nucleus. It is rather probable that in Leydig, Van Beneden, &c., the nuclear framework this, as in other organic structures, we have to do is typically a reticulum ; according to Strasburger, with various degrees of development and definite. Balbiani, and Korschelt, a twisted ribbon is the ness.

only or most frequent form ; according to Brass In the form also of the nucleus numerous modi and Rabl, both types may equally occur. A further fications occur. In the majority of cases, indeed, complication has been emphasised by Zacharias, it is more or less spherical, but it may be elongated, Pfitzner, Carnoy, and others-this, namely, that curved, horseshoe-shaped, necklace-like, and even besides the readily stained threadwork noted above branched. In the young stages of some ova it is (the so-called chromatin), whether this be in the like the entire cell, somewhat plastic, and is pulled form of a reticulum (Pfitzner) or of a coiled ribbon in and out in ameboid movements. In special con (Carnoy), there exists another—not readily stained ditions, furthermore, the nucleus may exhibit — framework of achromatin. This had indeed been peculiar deformations. It is in fact a peculiarly recognised though not insisted on by the first series sensitive and all-important part of the cell, suffering of investigators. To sum up, it is now generally with it in degeneration, changing with it in growth allowed that the framework or threadwork of the and division.

nucleus may exist as a network or as a coil, and In position the nucleus is typically central, where that it is in a sense double, consisting of readily as the presiding genius of the cell it shares and stainable chromatin on the one hand, and unstainperhaps controls the general protoplasmic life. But able achromatin on the other. It need hardly be it frequently suffers displacement both of a passive added that as there is considerable diversity of

[graphic]
[graphic]
« PrécédentContinuer »