Lamina

“ Whether the necessary forces are due to aerial pressures acting on the rear, or to forces directly impressed from without, is a matter of indifference. The conception of the lamina leads immediately to two schemes, according to which a primary wave may be supposed to be broken up. In the first of these the element dS, the effect of which is to be estimated, is supposed to execute its actual motion, while every other element of the plane lamina is maintained at rest. ”

“ The two projecting edges of the spirally-wound lamina, forming the arms, are provided with short incurved hairs or teeth, exactly like those on the lips. These project inward at right angles to the spiral line of junction between the two edges. The inner surface of the lamina supports two-celled, elongated papillæ, resembling those38 in the upper part of the neck, but differing slightly from them, according to Warming, in their footstalks being formed by prolongations of large epidermic cells; whereas the papillæ within the neck rest on small cells sunk amid the larger ones. ”

“ If the clay of an individual lamina be washed and carefully sifted, it will be found to be composed of grains of all shapes, sizes, and weights, down to the finest and most impalpable flour. It is impossible to believe that such a heterogeneous assemblage of grains could have been dropt into water without the particles being separated and sifted in their progress to the bottom. ”

“ The light proceeding from the cube was now circularly analysed, by means of the interposition of a lamina of mica of a proper thickness between the plate of Iceland spar and the analysing prism. The axis of this lamina lay so that the segments of the arcs were removed from the central point to the first and third quadrants. When the cube was yet unheated, its action was thus in direct opposition to its action in the first degree of its heating. ”

“ The tubes become filled up solidly much more commonly than do the parietal tubes; and the inner lamina, in such cases, is hardly distinct from the outer lamina. The denticuli often fail, or are present only on the lower sides of the septa; and very frequently the edge of the radius can only be said to be crenated. Notwithstanding these frequent anomalies, if a series of species and genera be taken, it is certain that there is, as might have been expected, a close relationship in internal structure, between the radii and the parietes. ”

“ New tubes are formed only at the basal edge of the outer lamina, by the bifurcation of the septa which form the tubes. In very young specimens there is only a single row of tubes; and in T. rosea this holds good throughout life: in this species (fig. 3 d) the tubes, in the single row, are large and quadrangular, and the outer lamina of shell is strengthened by numerous, small, internal, longitudinal plates. ”

“ Oil or grease, on the contrary, when applied directly upon wool, covers up these lamina or scales, thereby destroying their felting power, as is well known to all wool spinners, however little they may understand the real cause of its being so, further than the fact of giving to it a smooth gliding effect, so necessary for the object of their business. ”

“ The lamina, the outline of which is orbicular, cordate at the base, is shortly 5-to 7-lobed, with the lobes coarsely and irregularly dentate; it attains 4 to 41⁄2 feet in length and rather more in breadth. The first leaves in spring display before expanding the peculiar metallic red hue of copper.
The plant was discovered in South-eastern Tibet, where it is said to be often cultivated for the sake of its medicinal root; but it is supposed to grow in various parts of Western and North-western China, whence the supplies of rhubarb are derived. ”

“ In juveniles (Fig. 20) the pectoroabdominal seam contains no ligamentous tissue and is like the other interlaminal seams of the plastron. A lateral apex of the pectoral lamina projects upward behind the axillary scale on each side, in the position occupied by the apical scale of adults. Examination of a large series of specimens revealed that the apical scale of adults becomes separated from the lateral apex of the pectoral lamina at approximately the time when the hinge becomes functional as such. ”

“ They are, however, much fewer towards the base of the leaf, near the insertion of the petiole on the stem, but are not altogether absent. In the lamina they occur both in the parenchymatous tissue and also in the midrib (see fig. 4) , and are entirely surrounded by two or three layers of compressed colourless cells (see figs. 1 and 2) .
The upper epidermis is often arched outwards over the glands (see fig. 1) , but there are always at least two rows of cells between the epidermis and the compressed cells surrounding the gland, one of the rows being palisade cells. ”

“ Each molar consists of two laminae separated by a deep external fold, around the inner end of which the laminae are connected by a narrow bar. In the present condition of wear there is no indication of secondary furrows. The premolar is smaller than the molars. ”

“ The epidermal cells rest on a thick layer of most striking appearance (Fig. 141) , for it resembles, in an extraordinary degree, when examined superficially, a layer of chitin; it is called the laminated layer, and is characterized by the extreme regularity of the laminæ. 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. ”

“ It is deposited in fine, transparent, highly polished, brown- coloured laminae, possessing peculiar optical properties, on the inside of a vessel, in which cloth, first prepared with glue and then with lime, is made to revolve rapidly in water. It is much softer, more transparent, and contains more animal matter, than the natural incrustation at Ascension; but we here again see the strong tendency which carbonate of lime and animal matter evince to form a solid substance allied to shell. ”

“ Tar-acid resins for laminating.—The manufacture of laminated resin products is most economic when done on a large scale, in which case the impregnation of the paper or fabric becomes a continuous process, the material feeding from a roll through resin sirup and then through drying towers, where time and heat may be controlled. ”

“ Commonly the framework is so constructed that a number of trabeculae running parallel to one another are produced. This is for the purpose of especially strengthening the bone in that direction. This direction is in all cases found to be that in which the bone has to support its maximum strain while in position within the body. Usually the bone trabeculae are so narrow that there is no need for Haversian systems within them, and they therefore usually consist of a few laminae arranged parallel to the surface. These laminae include bone corpuscles as in the rest of the bone tissue. ”

“ Lamination.—If we apply to the dictionary for the word "lamination," we find that lamellar structure is the arrangements in thin plates or layers one over the other, usually having the end joints alternating, and it is a condition which allows of cleavage in one direction only. ”

“ While there is a general tendency in the group to mucilaginous degeneration of the cell-wall, in Laminaria digitata there are also glands secreting a plentiful mucilage. Secondary growth in thickness is effected by the tangential division of superficial cells. The most fundamental external differentiation is into holdfast and shoot. In Laminariaceae secondary cylindrical props arise obliquely from the base of the thallus. ”

“ To the latter we look for our yield of glue; to the fatty matter for the fat, and to the phosphates for the basis of fertilizers.
Bone cartilage is composed of carbon, hydrogen, oxygen and nitrogen, the percentage composition being practically constant, whether the cartilage be from an old or a young animal. The bones of the young are, however, much richer in cartilage than those of the old. This is reversed in the case of the inorganic or mineral matter, the old having the greatest yield of phosphates. ”

“ There are two modes of proceeding in forming the tissue, either of which may be adopted, as circumstances may render desirable. The first consists in coating a plate of glass with plain collodion, and upon this film applying a mixture of gelatine, sugar, coloring matter, and bichromate of potash. When this is dry, it is removed from the glass, and forms a pliant tissue, ready for exposure under a negative, after which it is mounted (exposed face down) on paper, either temporarily, by means of caoutchouc cement, or permanently, by means of albumen. ”

“ 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 fulling of flannels and broadcloths is effected by the felting principle. By the joint influence of the moisture and the pressure, certain of the fibres are brought into more intimate contact with each other; they adhere—not only the fibres, but; in a manner, the threads—and the cloth is taken from the mill shortened in all its dimensions; it has become a kind of felt, for the threads have disappeared, and it can be cut in every direction with very little or no unravelling; it is altogether a thicker, warmer, softer fibre. ”

“ Under the influence of moisture and pressure, aided by alkalis or acids, masses of wool thoroughly mat together, by the mutual interlocking of the fibres. It is thus that the shrinking and thickening of woollen textures under washing is accounted for, the capacity of wool cloth for felting or fulling being due to this condition of the fibre, possibly along with a certain shrinkage of the true fibre mass. The serrations are most numerous, acute, pointed and distinct in fine merino wools, as many as 2800 per in. ”

“ The thin upper-skin—the epidermis—which consists only of cellular tissue, and is of no special importance for the manufacture of glue. 2. The actual leather-skin, or corium, which consists of fibres of connective tissue and forms the actual object of the tanner as well as of the glue boiler. Underneath the corium lies the under-skin, which consists only of cellular tissue contaminated with particles of flesh and fat, which are detrimental to the manufacture of glue. Fig. 1 represents a section of the animal skin. O, is the epidermis, L, the corium, U, the under-skin. ”

“ A soft mass consists of about 50 parts of glue, 25 of wax or rosin, and 25 of glycerine. The glue is melted in the glycerine with the assistance of steam, and the wax or rosin added. The latter in melting mixes with the glue and glycerine, and finally the mineral color is added. The mass is poured in a liquid state into moulds of plaster of Paris, wood, or metal. The degree of hardness of the mass is increased by an addition of 30 to 35 per cent. of zinc white, or other mineral color, according to the color the article is to have. ”

“ Each corpuscle consists of 40 to 50 lamellae or coats, like the folds of an onion, thinner and closer to gether on approaching the centre. Each lamella is formed of an elastic material mixed with delicate con nective tissue fibres, and the inner surface of each is lined by a single continuous layer of endothelial cells. A double-contoured nerve fibre passes to each. ”

“ The powder of cocoa-nut shells, slate, of paper, plaster of Paris, of leather, clay, lime, fine sand, and many other substances, can all be combined with adhesives, acids, or chemical solvents in such a manner as to form what may be called generically cements, or substances, or pastes, which become hard. Any glue or gum, or liquid which will make two surfaces adhere, can be mixed with most organic or inorganic hard substances in powder so as to form a paste which, when dry, forms a solid, hard substance, because the grains of the powder are thereby cemented together. ”

“ The amputated limb of an animal being placed upon a table, let the operator hold with one hand the principal nerve, previously laid bare, and in the other let him hold a piece of zinc; let a small plate of lead or silver be then laid upon the table, at some distance from the limb, and a communication be formed, by means of water, between the [Pg 167] limb and the part of the table where the metal is lying. If the operator touch the piece of silver with the zinc, contractions will be produced in the limb the moment that the metals come into contact with each other. ”

“ Microscopic Structure—The wood of the root exhibits, in transverse section, concentric rings transversed by narrow medullary rays. Each ring contains a number of large vessels in its inner part, and more densely packed cells in its outer. The prevailing part of the wood consists of prosenchyme cells. Globular cells, loaded with yellow essential oil, are distributed among the woody prosenchyme. The latter as well as the medullary rays abounds in starch.
The bark is rich in oil-cells and also contains cells filled with mucilage ”

“ You will observe that the scales of the wool fibre are rather pointed than rounded at their free edges, and that at intervals we have a kind of composite and jagged-edged funnels, fitting into each other, and thus making up the covering of the cylindrical portion of the fibre. The sharpened, jagged edges enable these scales more easily to get under the opposing scales, and to penetrate inwards and downwards according to the pressure exerted. The free edges of the scales of wool are much longer and deeper than in the case of hair. ”