Fiber (anatomy)

“ When it is required to place into an instrument a fiber of any particular size, all that has to be done is to hold the frame of fibers toward a bright and distant light, and look at them through a low-angled prism. ”

“ The fibers of dyed black silk may be viewed with interest under the microscope. If a few threads of its warp are placed on a glass slide, and one or two drops of concentrated nitric acid placed in contact with them, the black color changes first to green, then to blue; a life-like motion is observed in all the fibers; they appear marked crosswise like the rings of an earthworm; the surface of each fiber appears loaded with particles of dyestuff; finally the fibers wholly dissolve in the acid. ”

“ In a general way, the nerve fibers resemble an electric cable wire with its central rod of copper, and its outer non-conducting layer of silk or gutta percha. Like the copper rod, the axis cylinder along which the nerve impulse travels is the essential part of a nerve fiber. ”

“ Fibers from these cells extend down through the brain and cord to the muscles, the fibers being collected into well-recognized bundles and the whole known as the motor tract. There may be one long fiber from a cell in the brain down through most of the cord or there may be a succession of shorter fibers that are not actually connected but are in close contact with each other. ”

“ Other observers also figure such fibers as extending centrad as nerve fibers. The axial fibers of the prism cells have each a dumbbell-shaped basal body at their entrance into the pigmented part of a cell. The evidence for a body of such shape in the pyramid cells was not conclusive, though a basal body for the axial fiber exists. The long pigment cells project or retract their pigment in light or darkness respectively and thus seem to serve to check the diffusion of light in the retina. ”

“ The bundle of nerve fibers which pass out together constitute a nerve, or, to speak more correctly, a nerve root. So far as yet observed no exception occurs; therefore we may safely assert that every nerve cell of the brain or spinal cord produces one nerve fiber and only one, and this fiber grows out from the nervous system into the tissues of the body. The fiber is single at its origin, but since we always find the peripheral fibers branching, we may add that the fiber is multiple at its termination. ”

“ There is no upper limit on the fiber diameter in the counting rules. Note that fiber width is measured at the widest compact section of the object. 1 fiber Although long fine fibrils may extend from the body of a fiber, these fibrils are considered part of the fiber if they seem to have originally been part of the bundle. Do not count If the object is ≤ 5 μm long, it is not counted. 1 fiber A fiber partially obscured by a particle is counted as one fiber. ”

“ Under the microscope, one of the specimens shows a single fiber, used as a tie at a position where a new bundle of fibers is added, weaving in and out of the old and new bundles. This gives the fibers much stronger binding than does twisting together alone. The twist is normally medium-hard to hard with an occasional crêpe twist.
Fur-wrapped cord, of which only fragments were recovered, consists of strips of hide with fur attached, about 1 cm. wide, wrapped around (S-twist) already prepared 2-ply agave fiber cord. No articles were found which had been constructed with fur-wrapped cord. ”

“ A quartz fiber of about the same size shows colors in the same way, but the tint is perfectly uniform on the fiber. If the color of the fiber is examined with a prism, the spectrum is found to consist of alternate bright and dark bands. Upon the screen are photographs taken by Mr. Briscoe, a student in the laboratory at South Kensington, of the spectra of some of these fibers at different angles of incidence. It will be seen that coarse fibers have more bands than fine, and that the number increases with the angle of incidence of the light. ”

“ Other Fibers While the fibers we have already discussed—Manila and Sisal—comprise by far the greater part of the raw material of cordage, we wish to mention in this chapter a fiber which, while now of comparatively slight importance, has the interesting feature of being a home product, and the cultivation of which at one time formed an industry of considerable magnitude in this country. ”

“ The fibre is decidedly inferior to flax and hemp in strength and tenacity; and, owing to a peculiarity in its microscopic structure, by which the walls of the separate cells composing the fibre vary much in thickness at different points, the single strands of fibre are of unequal strength. Recently prepared fibre is always stronger, more lustrous, softer and whiter than such as has been stored for some time—age and exposure rendering it brown in colour and harsh and brittle in quality. ”

“ Each fibre has a broad lumen and is very similar to hemp fibre. Examination of all these fibres, by the way, is best made in water as described under cotton.
Hemp is another bast fibre and as we have remarked it resembles the short fibres of flax; there is a broad lumen with an indistinct margin. ”

“ A coarse fiber may have a dozen or more, while such fibers as I find most useful have only two dark bands. Much finer ones exist, showing the colors of the first order with one dark band; and fibers so fine as to correspond to the white or even the gray of Newton's scale are easily produced.
Passing now from the most scientific test of the uniformity of these fibers, I shall next refer to one more homely. It is simply this: The common garden spider, except when very young, cannot climb up one of the same size as the web on which she displays such activity. ”

“ The lateral arrangement of the fibrils will, of course, be modified according whether a rod is circular, hexagonal, square, etc., in transverse section. It will also be remembered (p. 49) that Patten describes the retinal cells studied by him as composed of twin cells, and he gives the name retinophora to a pair. The system of fibers and fibrils in the rods he names a retinidium. Centrad the axial fibers are continued past the nucleus as a nerve fiber. ”

“ Under the action of the reagents the fibres composing this yarn, which must, of course, be suitably “teazed out” for mounting, are coloured a light blue, the centre, however, showing a yellow line, {37} marking the distribution in the interior canal of a non-cellulose fibre constituent. Should these effects not appear, it may be concluded that the acid requires to be strengthened. On the other hand, too great a concentration is equally to be avoided; it is evidenced by causing a distortion of the fibre, easily recognised by comparison with the fibre mounted in a neutral medium. ”

“ Now, if it is a remarkable fact that in a fully differentiated nervous network the constituent fibres are not improbably capable of vicarious action to almost any extent, much more remarkable does this fact become when we find that no two of these constituent nerve-fibres are histologically continuous with one another. Indeed, it seems to me we have here a fact as startling as it is novel. There can scarcely be any doubt that some influence is communicated from a stimulated fibre a to the adjacent fibre b at the point where these fibres come into close apposition. ”

“ On the contraction of the fibre a part of the spirit of animation becomes expended, and the fibre ceases to contract, though the stimulus continues to be applied; till in a certain time the fibre having received a supply of sensorial power is ready to contract again, if the stimulus continues to be applied. If the stimulus on the contrary be withdrawn, the same quantity of quiescent sensorial power becomes resident in the fibre as before its contraction; as appears from the readiness for action of the large locomotive muscles of the body in a short time after common exertion. ”

“ In the tissue, as in the cotton, every fibre appears to be endowed with the capacity of liberating energy in either of two very different ways; and whenever one part of the mass is made, by the appropriate stimulus, to liberate its energy in one of these two ways, all other parts of the mass do the same, and this no matter how far through the mass the liberating process may have to extend. ”

“ If the nerve-fibres were less independent, and if it were necessary that they should blend with and support each other, all accuracy of perception would be lost, and all information thus afforded would be pointless and confused. These silvery threads must, therefore, be spun out with an infinite degree of nicety. Imagine, for instance, the fibre which {158}connects the brain with some point on the foot,—its length cannot be less than one hundred thousand times greater than its diameter ”

“ This appearance is due, as the observations of Miss Alcock show, to alternate layers of connective tissue fibres arranged at right angles to each other, each fibre running a straight course and possessing its own nucleus. Although the fibres in each layer are packed close together, they are sufficiently apart to form with the fibres of the alternate layers a meshwork rather than a homogeneous structure, and thus the surface view of this layer shows a regular network of very fine spaces through which nerve-fibres and fluid pass. ”

“ The properties of matter which condition its adaptation to structural functions, first as a constituent of a living individual, and afterwards as a textile fibre, are homogeneous continuity of substance, with a high degree of interior cohesion, and associated with an irreducible minimum of elasticity or extensibility. The colloids show an infinite diversity of variations in these essential properties: certain of them, and notably cellulose (q.v.) ”

“ A description of each of the principal fibres is given, with the normal dimensions of the unbeaten fibres and the coloration given by the solutions specified. For general examination the lower powers of the microscope will be found most useful, the higher magnifications being employed for studying the markings and other characteristics of the fibres. The dimensions given of cotton, linen, and hemp fibres will not be met with in papers made from those materials, as in beating the lengths are shortened, and frequently the fibres are split longitudinally. ”

“ The matured fibres always collapse in the middle as described, and undergo no change in this respect when passing through all the various operations to which cotton is subject, from spinning to its conversion into pulp for paper-making.
Linen, or Flax Fibre, under the microscope, appears as hollow tubes, open at both ends, the fibres being smooth, and the inner tube very narrow, and joints, or septa, [10] appear at intervals, but are not furnished with hairy appendages as is the case with hemp. ”

“ The numerous filaments came to be known as protoplasmic processes; the other fibre was named, after its discoverer, the axis cylinder of Deiters. It was a natural inference, though not clearly demonstrable in the sections, that these filamentous processes are the connecting links between the different nerve cells and also the channels of communication between nerve cells and the periphery of the body. The white substance of brain and cord, apparently, is made up of such connecting fibres, thus bringing the different ganglion cells everywhere into communication one with another. ”

“ The fibre itself is not directly excitable by the outer agent which impresses the terminal organ. The optic fibres are unmoved by the direct rays of the sun; a cutaneous nerve-trunk may be touched with ice without feeling cold. ”

“ Thus the life of each fibre is insulated by this layer, which, like that of the whole organ, forms around it a kind of atmosphere, destined to defend and protect it, but which can, however, like the general layer, and even more than that, because the parts are nearer to each other, be the means of the communication of diseases from one fibre to another. ”

“ It must be said that the evidence we possess of chemical changes in the nerve-fibre is very meagre, no doubt because of their comparative insignificance. Still, small as the change is, it is sufficient to set off the highly unstable material in a muscular fibre and to produce chemical changes attended by the liberation, as we have seen, of mechanical energy. The change in a nerve-fibre can also produce changes in other organs. ”

“ All animal fibres are effectively dissolved by 10% solution of caustic potash or soda. The fabric or material is boiled in this solution for 10 minutes and exhaustively washed. Any residue will be vegetable or cellulose fibre. It must not be forgotten that the chemical properties of the fibre substances are modified more or less by association in combination with colouring matters and mordants. These may, in many cases, be removed by treatments which do not seriously modify the fibre substances. ”

“ Sharp action between the roll and the bed-plate will, no doubt, make speedy work of the fibre, but the result will be short particles of fibre only, which will not interlace to make a strong felt. Indeed, the action I refer to will reduce the long, strong fibre of linen to little better than that of wood or straw. ”

“ Fibers.—Like hairs, the various types of natural and artificial fibers can be distinguished from each other under the microscope. Like hairs too, individual fibers are not unique, but the expert usually can distinguish fibers from different fabrics. A major identifying characteristic of most fibers is color, and under the microscope many different shades of each color can be differentiated—for example, 50-100 shades of green or blue, and 25-30 shades of black. The microscopic appearance of three types of fibers—cotton, wool, and viscose—is illustrated in Commission Exhibit No. ”