The cytoplasm is largely concerned in the formation of spindle fibres and centrosomes, and such structures as the cell membrane, cilia, or flagella, the coenocentrum, nematoplasl~ or vibrioids and physodes are also products of its activity.
They are more easily seen, when the nucleus is about to undergo mitosis, at the ends of the spindle, where they form the centres towards which the radiating fibres in.
Coincident with these changes the nuclear membrane disappears and a spindle-shaped or barrelshaped group of threads makes its appearance in.
At each pole of this spindle figure there often occur fibres radiating in all directions into the cytoplasm, and sometimes a minute granular body, the centrosome, is also found there.
(2) Metaphase.The chromosomes pass to the equator of the spindle and b,ecome attached to the spindle-fibres in such a way that they form a radiating starthaped figureAster-when seen from the pole of the spindle.
(3) Anaphase.The longitudinal division of the chromosomes is completed by the time they have taken up their position in the nuclear plate, and the halves of the chromosomes then begin to move along the spindle-fibres to opposite poles of the spindle (fig.
The spindle figure is probably the expression of forces which are set up in the cell for the purpose of causing the separation of the daughter chromosomes.
Hartog has endeavoured to show that it can only he formed by a dual force, analagous to that of magnetism, the spindle-fibi es being comparable to the lines of force in a magnetic field and possibly due to electrical differences in the cell.
The spindle arises partly from the cytoplasm, partly from the nucleus, or it may be derived entirely from the nucleusintranuclear spindleas occurs in many of the lower plants (Fungi, &c.).
The formation of the spindle begins in the prophases of division.
A layer of delicate filamentous cytoplasmkinoplasmmay collect around the nucleus, or at its poles, out of which the spindle is formed.
As division proceeds, the filamentous nature of this cytoplasm becomes more prominent and the threads begin either to converge towards the poles of the nucleus, to form a bipolar spindle, or may converge towards, or radiate from, several different points, to form a multipolar spindle.
The wall of the nucleus breaks down, and the cytoplasmic spindle-fibres become mixed with those derived from the nuclear network.
The formation of the spindle differs in details in different plants.
The chromosomes now become attached to the spindle-fibres (fig.
In Fucus and allied forms the spindle-fibres between the daughter nuclei disappear early and the new cell-wall is formed in the cytoplasm.
F, Separation of the chromosomes into two groups G, Chromosomes grouped at opposite ends of the spindle to forn the daughter nuclei.
They are present from the beginning of the development of the cell-wail, and arise from the spindle fibres, all of which may be continued as connecting threads (endosperm of Tamus communis), or part of them may be overlaid by cellulose lamellae (endosperm of Lilium Martagon), or they may be all overlaid as in pollen mother-cells and pollen grains of Helleborus foetidus.
In length, actuating a universal joint on the first spindle of the register; it consisted of an air-tight thin metal tube with a coned fore-end, carrying flat metal vanes set at an angle.
4 the shoe H is secured to the taffrail, and the rotator in the water is hooked to the eye of the spindle M by the hook D.
Case A contains the wheelwork, and case E the spindle and steel ball FIG.
It represented the goddess, standing in the stiff archaic style, holding a spear in her right hand, in her left a distaff and spindle or a shield.
Dorsal papillae spindle-shaped or clubshaped.
After the division and cleavage of the chromosomes of the original nucleus have taken place they pass from the equator to the poles of the spindle, rearranging themselves close to the separated centrosomes to form daughter nuclei.
Present, that at one end of the spindle may be unusually large, the other of natural size, and they may vary in shape.
First they are round or oval in shape; later they become spindle shaped, arranging themselves in layers.
These become spindle shaped with their long axis more and more assuming a position at right angles to the vessels (fig.
These are spindle shaped and have long processes.
The "rod-and-disk" form of Sidney Young is a series of disks mounted on a central spindle and surrounded by a slightly wider tube.
Here the two elements, ovum and yolk-cells, are surrounded by a shell of operculate or of spindle-capped types.
Either (I) by the Mexican crusher or arrastra, in which the grinding is effected upon a bed of stone, over which heavy blocks of stone attached to cross arms are dragged by the rotation of the arms about a central spindle, or (2) by the Chilean mill or trapiche, also known as the edge-runner, where the grinding stones roll upon the floor, at the same time turning about a central upright - contrivances which are mainly used for the preparation of silver ores; but by far the largest proportion of the gold quartz of California, Australia and Africa is reduced by (3) the stamp mill, which is similar in principle to that used in Europe for the preparation of tin and other ores.
This ring runs between friction wheels and is provided with teeth on its inner periphery, and these teeth transmit motion to a pinion on a spindle having at its other end another pinion which, through an intermediate wheel, rotates the heliometer tube.
The transmission spindle, just mentioned, carries at its end a head, 74, which, if turned directly, gives the second speed.
All textile work was done by hand; the only devices known were the bark peeler and beater, the shredder, the flint-knife, the spindle, the rope-twister, the bodkin, the warp-beam and the most primitive harness.
Twining and spinning were done with the fingers of both hands, with the palm on the thigh, with the spindle and with the twister.
In Scott's sight, mark iv., there is a longitudinal level pivoted at one end and provided with a degree scale up to 4°; the level is moved by a spindle and micrometer screw reading to 2'.
The rocking-bar is moved by a rack g into which a pinion on a cross-spindle j gears; the cross-spindle is moved by means of a worm-wheel into which a worm on the longitudinal FIG.
Spindle of the hand-wheel gears; one end of the cross-spindle moves the range drum 2'.
AMOS BRONSON ALCOTT (1799-1888), American education alist and writer, born on Spindle Hill, in the town of Wolcott, New Haven county, Connecticut, on the 29th of November 1799.
No spindle-whorls were found, but there were many varieties of cloth, platted and woven, bundles of yarn and balls of string.
There also might be seen the flat circular temalacatl or " spindle-stone," where captives armed with wooden weapons were allowed the mockery of a gladiatorial fight against well-armed champions.
After the birth of a child, the tonalpouhqui or;sun-calculator drew its horoscope from the signs it was born under, and fixed the time for its solemn lustration or baptism, performed by the nurse with appropriate prayers to the gods, when a toy shield and bow were provided if it was a boy, or a toy spindle and distaff if it was a girl, and the child received its name.
Was of skins of woven aloe and palm fibre, but at the time of the conquest cotton was largely cultivated in the hot lands, spun with a spindle, and woven in a rudimentary loom without a shuttle into the mantles and breech-cloths of the men and the chemises and skirts of the women, garments often of fine texture and embroidered in colours.
The limbs of the U are further twisted together in a looser or tighter coil, the axis of which may be traversed by a "spindle" muscle arising from the posterior end of the body.
The spindle-muscle is seen overlying the rectum.
Thread-Work.Stone spindle whorls (103) are common in the prehistoric age; wooden ones were usual, of a cylindrical form (104) ~n the XIIth, and conical (105) in the XVIIIth Dynasty.
Is said to undergo division by mitosis essentially of the same character, with the formation of a spindle and the differentiation of chromosomes.
The method once exclusively used consists in mixing the raw materials with a large quantity of water in a wash mill, a machine having radial horizontal arms driven from a central vertical spindle and carrying harrows which stir up and intermix any soft material placed in the pit in which the apparatus revolves.
The Power Was Transmitted To The Paddles By Bevel Wheels F, G, Rotating A Spindle Passing Through A Stuffing Box In The Bottom Of The Calorimeter.
Formerly Lowell was called the " Spindle City " and the " Manchester of America," but it was long ago surpassed in the manufacture of textiles by Fall River and New Bedford: in 1905 the value of the cotton product of Lowell, $19,340,925, was less than 60% of the value of cotton goods made at Fall River.