Filament

“ As the cell elongates, the axial filament grows out, the nebenkern approaches it, and a junction is effected in such a way that the axial filament runs over the surface of the nebenkern. (Figs. 18, 27, 28, and 30.) At first the nebenkern is still almost round, but it begins to elongate and the dark inner ball sends out a protrusion to the nucleus, and sometimes back to the point of separation between the external envelope and the axial filament. The outside ring disappears and the dark mass moves down the axial filament. (Fig. 31.) ”

“ The protoplasm of the cells has a few small granules scattered through it, and is colored uniformly of a pale blue-green. No nucleus can be seen.
If the filament is broken, there may generally be detected a delicate, colorless sheath that surrounds it, and extends beyond the end cells (Fig. 6, c) . The filament increases in length by the individual cells undergoing division, this always taking place at right angles to the axis of the filament. New filaments are produced simply by the older ones breaking into a number of pieces, each of which rapidly grows to full size. ”

“ The principles of its action and the method of calibration are the same. The pyrometers of Morse, and of L. F. C. Holborn and F. Kurlbaum depend on the employment of a glow lamp filament as standard of comparison, the current through which is adjusted to make the intrinsic brilliancy of the filament equal to that of the source. When this adjustment is made the filament becomes invisible against the image of the source as background, and the temperature of the source may be determined from an observation of the current required. ”

“ A phenomenon similar to one we have already seen in cell-division among plants now shows itself. The nucleus becomes broken up into a number of filaments, which lie together in a bundle, each filament stretching from pole to pole of the spindle. Exactly in its central point every filament shows a knot-like enlargement, and from the close approximation of the knots there results a thick zone of protoplasm in the equator of the spindle. ”

“ If the distance between two adjacent filaments be considerable, the curve will simply meet the filament at the angle α already referred to; but if they be sufficiently near together, we shall have a continuous catenary curve forming a hanging loop between one filament and the other. And when this is so, and the radial filaments are more or less symmetrically interspaced, we may have a beautiful system of honeycomb-like depressions over the surface of the organism, each cell of the honeycomb having a strictly defined geometric configuration. ”

“ The incandescent bulbs which illuminate our buildings consist of a fine, hairlike thread inclosed in a glass bulb from which the air has been removed. When an electric current is sent through the delicate filament, it meets a strong resistance. The heat developed in overcoming the resistance is so great that it makes the filament a glowing mass. The absence of air prevents the filament from burning, and it merely glows and radiates the light. ”

“ The filament forms the body of the hair, and the bulb the root. The large hairs have their root, and even part of the filament, enclosed in a small membraneous vessel or capsule. The size of this [Pg 29] sheath is proportionate to the size of the root, being always rather larger, that the root may not be too much confined, and that some space may remain between it and the capsule. The root or bulb has two parts, the one external, the other internal. The external is a pellicle composed of small laminæ; the internal is a glutinous fluid, in which some fibres are united ”

“ The shunt-circuit extends from the place through a galvanometer to the filament. His specifications disclose that the vacuous space within the globe is a conductor of current between the plate anode and the filament; that the strength of the current in the filament-to-plate circuit through the vacuum depends upon the degree of incandescence at the filament; and that the plate anode is preferably connected to the positive side of the current supply. The claims of the patent are for the combination of the filament, plate and interconnecting circuit, including the galvanometer. ”

“ An experiment may serve as an illustration and as a means of bringing out other features of interest. Some time ago I showed that a lamp filament or wire mounted in a bulb and connected to one of the terminals of a high tension secondary coil is set spinning, the top of the filament generally describing a circle. This vibration was very energetic when the air in the bulb was at ordinary pressure and became less energetic when the air in the bulb was strongly compressed. ”

“ Thousands of operatives are constantly employed in forming up these threads by hand, adding filament by filament to the thread as required, while watching the unwinding from the cocoon of many miles of filament in order to produce a single pound of the raw silk thread, making up the thread unaided by any mechanical device beyond a simple reel on which the thread is wound as finished, and a basin of heated water in which the cocoons are placed. ”

“ The rotational streaming continues until the entire filament is wound up, which in exceptional cases may make four or five coils inside the animal.
The mouth has considerable grasping power. This is shown in Figure 32 where a filament of Oscillatoria was bent upon itself by the mouth and then rolled up in the body by the endoplasm in the same manner as a single filament. The mere viscosity of the endoplasm would be insufficient to bring about the bending of the filament. For the sake of comparison it should be added that a similar grasping power is also present in paramecium. ”

“ In my last letter I told how electrons are boiled out of a heated filament. The hotter the filament the more electrons are emitted each second. If the temperature is kept steady, or constant as we say, then there are emitted each second just the same number of electrons. When the filament is enclosed in a vessel or glass bulb these electrons which get free from it cannot go very far away. ”

“ Fasten a small yellow bead anther on each end of the wire filaments, by bending the end of the wire over the bead with pincers. Fold the filament wires in half.
4. To make the pistil and stem,—
(a) Cut a piece of heavy wire six inches long—to form the stem.
(b) On one end, fasten a large yellow bead to form the stigma. Cut a piece of fine wire eight inches long. One inch below the stigma bead, hold the folded filament wires in a little bundle around the stem wire, and wind with the fine eight inch wire—to form the ovary. The heavy wire between the stigma and the ovary represents the style. ”

“ The long filaments of the penumbra may be used in a similar way, flexible as they are, and rooted, as it were, at one end, while the other sways in the currents of the solar atmosphere, yielding to it as freely as the grasses to the water, or a streamer to the air; and the analogy is noteworthy in this: that one end of the filament is commonly made fast, while the other is left free. ”

“ In the modern incandescent lamp the filament is generally constructed by preparing first of all a form of soluble cellulose. Carefully purified cotton-wool is dissolved in some solvent, such as a solution of zinc chloride, and the viscous material so formed is forced by hydraulic pressure through a die. The long thread thus obtained, when hardened, is a semi-transparent substance resembling cat-gut, and when carefully carbonized at a high temperature gives a very dense and elastic form of carbon filament. ”

“ The usual type of vacuum tube consists of an evacuated glass vessel in which are enclosed three elements, the filament, the plate, and the grid. When the tube is in operation an electron current flows between the filament which is heated by an auxiliary source of power and the plat, the magnitude of this current being controlled by the grid. ”

“ This baking of the bamboo produces a tough fiber of carbon. Various forms of thread have been carbonized and used. Filaments are now made by pressing finely pulverized carbon, with a binding material, through small dies. The filaments are made of such sizes and lengths that will adapt them to the particular current with which they are to be used. The longer the filament, the greater its resistance, and the greater the voltage necessary to push the current through it. ”

“ Here we are, we got our option on the perfect filament, and all we want's canadium. Nobody knows there's more canadium in the world than will go on the edge of a sixpence except me and you. Nobody has an idee the perfect filament's more than just a bit of theorising. Fifty tons of quap and we'd turn that bit of theorising into somethin'——. ”

“ If we suppose the filament AB surrounded by other filaments moving with not very different velocities, the frictional or viscous resistance on its surface will be small enough to be neglected, and if the fluid is incompressible no internal work is done in change of volume. Then the work done by external forces will be equal to the kinetic energy produced in the time considered.
The normal pressures on the surface of the mass (excluding the ends A, B) are at each point normal to the direction of motion, and do no work. ”

“ Sections of the filaments are prepared by cutting in a microtome, the filaments being previously agglutinated into a stiff bundle by means of any of the usual stiffening solutions, and after drying, embedded in wax in the usual way. Sections of fresh stems and tissues are cut with a “section” razor.
Having prepared the objects, their examination under the microscope necessarily divides itself into:— (1) the determination of external features; (2) the diagnosis of chemical composition. The fibres themselves will be individually considered in regard to microscopic features. ”

“ Each rod is surrounded by a layer of pigment that prevents light from passing from one to another, and the optic nerve passing into the base of the compound structure sends a sensitive filament into each one. ”

“ Occasionally there may be found indications of the characteristic clamp-connections in the septate filaments; a small semicircular branch, which is given off from a mycelium immediately above a transverse wall, bends round to fuse with the filament just below the septum, thus serving as a small loop-line connecting the cell-cavity above and below a cross wall. ”

“ The other movement is one of direct progression. A filament will, after a period of quiescence, begin to move forward, end on as it were, and having advanced a certain distance will, without any discoverable cause, suddenly reverse the direction and retrograde. It is a very interesting sight sometimes to watch these minute organisms in their advance across the field of the microscope, I have seen in O. tenuis the two or three end cells waving backwards and forwards slowly and deliberately as though the filament were feeling its way across the field of view. ”

“ In some instances, as in Tamarix gallica, Peganum Harmala, and Campanula, the base of the filament is much dilated, and ends suddenly in a narrow thread-like portion. In these cases the base may give off lateral stipulary processes, as in Allium and Alyssum calycinum. ”

“ Every filament of the cotton will be laid hold of by each set of teeth, when their surfaces are thus drawn over each other; the teeth of a will pull them in a forward direction, while those of b will tend to retain them, or to pull them backwards. The loops or doublings will, by both movements, be opened or drawn out, so that the flocks will be converted into rows of parallel filaments, lying alongside or before each other. Each tooth will secure to itself one or more of them, and by the friction of its sides, as well as the hooks of its points, will draw them to their utmost elongation. ”

“ It has been found necessary for instance to suspend the anode in gimbals during the making of the tube seal owing to its great weight, and special devices have been made to hold the filament grid assembly in place while it is being sealed in, otherwise the strains produced by its weight cause cracking of the seal. ”

“ Each filament is capable of being suddenly protruded, thus becoming a free whip-like appendage, and these are so numerous as to be very effectual in seizing and holding the living beings on which the animal feeds. ”

“ If we inclose an incandescent bulb in a tight box with a round hole in one side of it, every spot on the incandescent filament will be giving off light in every direction, but all the light will be cut off by the box except that which happens to have the direction which takes it out through the hole. ”

“ If a screen is placed in front of the hole, all these cones of light will strike on it, and it will be illuminated in a pattern which is made up of all the cones from all the incandescent spots which make up the filament, but these will overlap so much that one cannot be told from another. ”

“ It was essential that the vessel containing the filament should be entirely of glass; that the current should be conveyed in and out this by means of platinum wires hermetically sealed through the glass; and that the glass globe must be as thoroughly exhausted as possible. This last requirement proved a difficult one for a time, but by improved methods it finally became possible to produce almost a perfect vacuum in the bulbs, with a corresponding increase in the efficiency of the lamps. ”

“ The toughness of these [178] filaments, considering that each is finer than the thinnest strand of silk, is remarkable. Their strength, however, may be easily accounted for, when we know that each is composed in reality of innumerable delicate threads, bound together by a subtle gelatinous fluid. This phenomenon may be made out quite distinctly with a common hand lens, if the following simple experiment be adopted: Make a Mussel construct its thread in such a way that the disc of each is planted on the face of the glass. ”