Wehnelt discovered that the same effect could be produced by using instead of a carbon filament a platinum wire covered with the oxides of calcium or barium, which when incandescent have the property of copiously emitting negative ions.
Fleming invented in 1904 a detector called an oscillation valve or glow lamp detector made as follows: 1 A small carbon filament incandescent lamp has a platinum plate or cylinder placed in it surrounding or close to the filament.
Inner capsule, continuous with wall of the filament, f.
So extensible is viscous glass that it can be drawn out into a filament sufficiently fine and elastic to be woven into a fabric.
A vortex filament must close on itself, or end on a bounding surface, as seen when the tip of a spoon is drawn through the surface of water.
A girl with a small hand brush of twigs keeps stirring them in the water till the silk softens, and the outer loose fibres (floss) get entangled with the twigs and come off till the end of the main filament (maitre brin) is found.
If a series of such elements, all equally and longitudinally magnetized, were placed end to end with their unlike poles in contact, the external action of the filament thus formed would be reduced to that of the two extreme poles.
The same would be the case if the magnetization of the filament varied inversely as the area of its cross-section a in different parts.
Pa, Post-anal lobe of the female (compare the jointed filament in Thelyphonus, fig.
King patented filament electric lamps exhausted by the same methods.
An alternative method consisted in passing an electric current through a filament of the tetroxide in a vacuum.
In very many cases the pollen is carried to the stigma by elongation, curvature or some other movement of the filament, the style or stigma, or corolla or some other part of the flower, or by correlated movements of two or more parts.
Consequently, each primitive filament has a descending and an ascending ramus, and instead of each row forming a simple plate, the plate is double, consisting of a descending and an ascending lamella.
Complications follow upon this in other forms. Even in Mytilus and Arca a connexion is here and there formed between the ascending and descending rami of a filament by hollow extensible outgrowths called " interlamellar junctions " (il.
Nevertheless the filament is a complete tube formed of chitinous substance and clothed externally by ciliated epithelium, internally by endothelium and lacunar tissue - a form of connective tissue - as shown in fig.
In Anodonta, besides being thickened, the skeletal substance of the filament develops a specially dense, rod-like body on each side of each filament.
B,Diagram of the posterior face of a single complete filament with descending ramus and ascending ramus ending in a hook-like process;ep.,ep.,the ciliated junctions; il,j ., inter-lamellar junction.
Rudimentary cephalic eyes occur in the Mytilidae and in Avicula at the base of the first filament of the inner gill, each consisting of a I pigmented epithelial fossa containing a cuticular lens.
Such an oscillation valve was first used by Fleming as a receiver for wireless telegraph purposes in 1904 as follows: - In between the receiving antenna and the earth is placed the primary coil of an oscillation transformer; the secondary circuit of this transformer contains a galvanometer in series with it, and the two together are joined between the external negative terminal of the carbon filament of the above-described lamp and the insulated platinum plate.
The thallus in all cases consists of a branched filament of cells placed end to end, as in many of the Green Algae.
The poles at the ends of an infinitely thin uniform magnet, or magnetic filament, would act as definite centres of force.
Such a filament is called a simple magnetic solenoid, and the product aI is called the strength of the solenoid.
Paf, Post-anal segmented filament corresponding to the post-anal spine of Limulus.
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.
Patten in 1824; whilst in 1881 Rankine Kennedy resuscitated the idea for the purpose of exhausting filament electric lamps.
With a supply pressure of 200 volts a 5 c.p. carbon filament lamp takes only 0.1 ampere; hence unless a meter will begin to register with 1 1 - 6 - ampere it will fail to record the current consumed by a single small incandescent lamp. In a large supply system such failure would mean a serious loss of revenue.
The long connective of the single stamen is hinged to the short filament and has a shorter arm ending in a blunt process and a longer arm bearing a half-anther.
3, The same, when disturbed by the entrance of the proboscis of the bee in the direction of the arrow; f, filament; c, connective; s, the obstructing half of the anther.
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.
The four orders now retained exhibit successive stages in the modification of the ctenidia by reflection and concrescence of the filament, but other organs, such as the heart, adductors, renal organs, may not show corresponding stages.
Next follows the operation of cleaning, in which the silk is simply reeled from one bobbin to another, but on its way it passes through a slit which is sufficiently wide to pass the filament but stops the motion when a thick lump or nib is presented.
Edison in the United States, were engaged in struggling with the difficulties of producing a suitable carbon incandescence electric lamp. Edison constructed in 1879 a successful lamp of this type consisting of a vessel wholly of glass containing a carbon filament made by carbonizing paper or some other carbonizable material, the vessel being exhausted and the current led into the filament through platinum wires.
In all these cases, however, the end-cells of the filaments each give rise to a carpospore, and the aggregate of such sporiferous filaments is a cystocarp. Again, in the family of the Gelidiaceae, the single filament arising from the carpogonium grows back into the tissue and preys upon the cells of the axis and larger branches, after which the end-cells give rise to carpospores and a diffused cystocarp is formed.
The nucleus of the ooblastema filament dominates the FIG.
He has also seen Pleurococcus viridis dividing so as to form a filament, but has not succeeded in seeing the formation of zoospores as described by Chodat.
The experiment of Engelmann referred to deserves to be mentioned here, if only in illustration .of the use to which algae have been put in the study of physiological problems. Engelmann observed that certain bacteria were motile only in the presence of oxygen, and that they retained their motility in a microscopic preparation in the neighbourhood of an algal filament when they had come to rest elsewhere on account of the exhaustion of oxygen.
After the bacteria had all been brought to rest by being placed in the dark, he threw a spectrum upon the filament, and observed in what region the bacteria first regained their motility, owing to the liberation of oxygen in the process of carbon-assimilation.
19 a lateral surface either, in which case they are said to be free; when mucilage does occur on the lateral wall, it appears as the sheath surrounding either the single filament, or a sheaf of filaments of common origin.
The cells of the filament may be all alike, and growth may occur equally in all parts (Oscillatoriaceae); or certain cells (heterocysts) may become marked off by their larger size and the transparency of their contents; in which case growth may still be distributed equally throughout (Nostoc), or the filament may be attached where the heterocyst arises, and grow out at the opposite extremity into a fine hair (Rivulariaceae).
" True " branching arises only by the longitudinal division of a cell of a filament and the lateral outgrowth of one of the cells resulting from the division (Sirosiphonaceae).
Phormidium sp., single filament with hormogonium.
Among colonial Desmidiaceae, the break-up of the filament is a preliminary to this conjugation; otherwise the process is the same.