As the powers of the telescope were gradually developed, it was found that the finest hairs or filaments of silk, or the thinnest silver wires that could be drawn, were much too thick for the refined purposes of the astronomer, as p p they entirely obliterated the image of a star in the more powerful telescopes.
(I) The polyp, when present, is without the strongly developed longitudinal retractor muscles, forming ridges (taeniolae) projecting into the digestive cavity, seen in the scyphistoma or scyphopolyp. (2) The medusa, when' present, has a velum and is hence said to be craspedote; the nervous system forms two continuous rings running above and below the velum; the margin of the umbrella is not lobed (except in Narcomedusae) but entire; there are characteristic differences in the sense-organs (see below, and Scyphomedusae); and gastral filaments (phacellae), subgenital pits, &c., are absent.
They may bear accessory filaments or tentilla (f'), covered thickly with batteries of nematocysts, to which these organisms owe their great powers of -offence and defence.
Each palpacle is a tactile filament, very extensile, without accessory filaments or nematocysts.
The base of the stem bears numerous cell-filaments (rhizoids) which fix the plant to the substratum upon which it is growing.
This is evident in the case~ of such plants as have a body consisting of filaments or plates of cells, and is little less conspicuous in those whose mass is but small, though the cells are evidently capable of computation in three dimensions.
In the first, which are called ectotropic, the fungal filaments form a thick felt or sheath round the root, either completely enclosing it or leaving the apex free.
The other type is called endctropic. The fungal filaments either penetrate the epidermis of the root, or enter it from the stem and ramify in the interior.
The organic compounds of the latter are absorbed by the protruding fungal filaments, which take the place of root-hairs, the tree ceasing to develop the latter.
These occur on the tips of tendrils and on the tentacles of Drosera; (2) sensitive papillae found on the irritable filaments of certain stamens; and (3) sensitive hairs or bristles on the leaves of Dionaea muscipula and Mimosa pudicaall of which are so constructed that any pressure exerted on them at once reacts on the protoplasm.
In Plotus, the snakebird, the pyloric chamber of the stomach is beset with a mass of hair-like stiff filaments which permit nothing but fluid to pass into the duodenum.
The prostomium has many long filaments which recall the gills of the Sabellids, &c. The nephridia are specialized into two series, as in the last-mentioned worms. (5) Spioniformia (including Chaetopterus, Spio, &c.) and (6) Scoleciformia (Arenicola, Chloraema, Sternaspis) are the remaining groups.
Curiously enough, however, they differ from the cephalic Molluscan eye in the fact that, as in the vertebrate eye, the filaments of the optic nerve penetrate the retina, and are connected with the re surfaces of the nerve-end cells nearer the lens instead of with the opposite end.
It stretches forward as far as the brain, and in Carinella is again continued in front of it, whereas in the Heteronemertines the innervation of the anterior extremity of the head, in front of the brain, takes the form of more definite and less numerous branching stems. The presence of this plexus in connexion with the central stems, sending out nervous filaments amongst the muscles, explains the absence, in Pro-, Mesoand Heteronemertines, of separate and distinct peripheral nerve stems springing from the central stems innervating the different organs and body-regions, the only exceptions being the L.N.
Tantalum has in recent years been turned to economic service, being employed, in the same manner as tungsten, for the production of the filaments employed in incandescent electric lighting.
An actual magnet may generally be regarded as a bundle of magnetic filaments, and those portions of the surface of the magnet where the filaments terminate, and socalled " free magnetism " appears, may be conveniently called poles or polar regions.
A more precise definition is the following: When the magnet is placed in a uniform field, the parallel forces acting on the positive poles of the constituent filaments, whether the filaments ' For the relations between magnetism and light see Magnetooptics.
Similarly, the forces acting in the opposite direction on the negative poles of the filaments have a resultant at another point S, which is called the south or negative pole.
Evergreen shrub with flattened leaf-like cladodes, native in the southerly portion of England and Wales; the small flowers are unisexual and borne on the face of the cladode; the male contains three stamens, the filaments of which are united to form a short stout column on which are seated the diverging cells of the anthers; in the female the ovary is enveloped by a fleshy staminal tube on which are borne three barren anthers.
The slender filaments of the stamens vary widely, often in the same flower; the anthers are linear to ovate in shape, attached at the back to the filament, and open lengthwise.
He supposed that the filaments of water which graze along the sides of the pipe lose a portion of their velocity; that the contiguous filaments, having on this account a greater velocity, rub upon the former, and suffer a diminution of their celerity; and that the other filaments are affected with similar retardations proportional to their distance from the axis of the pipe.
At a time when the Cartesian system of vortices universally prevailed, he found it necessary to investigate that hypothesis, and in the course of his investigations he showed that the velocity of any stratum of the vortex is an arithmetical mean between the velocities of the strata which enclose it; and from this it evidently follows that the velocity of a filament of water moving in a pipe is an arithmetical mean between the velocities of the filaments which surround it.
The shell is thick, and operculate in some forms; thin, and provided with filaments, in others; in the latter cases it may contain only a few yolk-granules suspended in an albumen-like substance.
The metal is manufactured, for use as filaments in electric lamps, by the action of sodium on sodium tantalofluoride.
The essence of his views is contained in the following passage, which he follows up with the conclusion "that one and the same kind of living filaments is and has been the cause of all organic life": "Would it be too bold to imagine that, in the great length of time since the earth began to exist, perhaps millions of ages before the commencement of the history of mankind, - would it be too bold to imagine that all warm-blooded animals have arisen from one living filament, which the great First Cause endued with animality, with the power of acquiring new parts, attended with new propensities, directed by irritations, sensations, volitions and associations, and thus possessing the faculty of continuing to improve by its own inherent activity, and of delivering down these improvements by generation to its posterity, world without end!"
FitzGerald) from a structure of tangled or interlaced vortex filaments pervading its substance, which might conceivably arrange themselves into a stable configuration and so resist deformation.
The species are numerous, and are distinguished one from another by the scales of the bulb being woolly or smooth on the inner surface, by the character of the flower-stalks, by the filaments being hairy or otherwise, and by other characters.
For instance, in many flowers the filaments are at first directed outwards so that self-pollination is not possible, but later incline towards the stigmas and pollinate them (e.g.
In Mirabilis Jalapa and others the filaments and style finally become intertwined, so that pollen is brought in contact with the stigma.
5); or the anthers are loosely fixed on long thread-like filaments as in grasses (fig.
Cardium belongs to the order of Lamellibranchia in which the gills present the maximum of complexity, the original vertical filaments of which they are composed being united by interfilamentar and interlamellar junctions.
The marginal tentacles may be very numerous or may be few in number or even absent altogether; and they may be simple filaments, or branched in a complicated manner.
These filaments are so fine and are set so closely together that they appear to form a continuous membrane until examined with a lens.
The microscope shows that the neighbouring filaments are held together by patches of cilia, called " ciliated junctions," which interlock with one another just as two brushes may be made to do.
II, A a portion of four filaments of a ctenidium of the sea-mussel (Mytilus) is represented, having precisely the same structure as those of Arca.
The filaments of the gill (ctenidium) of Mytilus and Arca thus form two closely set rows which depend from the axis of the gill like two parallel plates.
These are actually reflected at a sharp angle - doubled on themselves in fact - and thus form an additional row of filaments (see fig.
This is the condition seen in Arca and Mytilus, the so-called plates dividing upon the slightest touch into their constituent filaments, which are but loosely conjoined by their " ciliated junctions."
12) give place to solid permanent inter-filamentar junctions, so that the filaments are converted, as it were, into a trellis-work.
Then let us suppose that the inter-lamellar junctions already noted in Mytilus become very numerous, large and irregular; by them the two trellis-works of filaments would be united so as to leave only a sponge-like set of spaces between them.
Having entered by the apertures left in the trelliswork formed by the united gill-filaments (fig.
- View from the ventral (pedal) aspect of the animal of Arca noae, the mantle-flap and gill-filaments having been cut away.
In the drawing of Dreissensia the individual filaments f,f,f are cut across in one lamella at the A.
Section across the axis of a ctenidium with a pair of plates - flattened and shortened filaments - attached.
The filaments take on a secondary grouping, the surface of the lamella being thrown into a series of halfcylindrical ridges, each consisting of ten or twenty filaments; a filament of much greater strength and thickness than the others may be placed between each pair of groups.
- Filaments of the Ctenidium of Mytilus edulis.
In Arca this can be seen with far less trouble, for the filaments are more easily removed than are the consolidated lamellae formed by the filaments of Anodonta, and in Arca the free axes of the ctenidia are large and firm in texture (fig.
The gill axis d is seen lying in the sub-pallial chamber between the foot b and the mantle c. From it depend the gillfilaments or lamellae - formed by united filaments - drawn as black lines f.
A,Part of four filaments seen from the outer face in order to show the ciliated junctions c.j.
F, Constituent open between the filaments in filaments; trf, fibrous tissue of the irregular rows separated horitransverse inter-filamentar junczontally by the transverse intertions; v, blood-vessel ilj, Interfilmentar junctions.