In some cases the plastid disappears and the crystalline pigment only is left.
Starch grains may often be seen in contact with the pigment crystals.
It has been suggested by several botanists, with considerable plausibility, that the ultra-violet or chemical rays can be absorbed and utilized by the protoplasm without the intervention of any pigment such as chlorophyll.
The pigment is also principally localized in this layer, although sometimes it is present even deeper down within the musculature.
In addition to its brilliance, vermilion is a pigment of great intensity and durability, remaining unaffected by acid fumes.
As the mineral only yields from 2 to 3% of the pigment, it is not surprising to learn that the pigment used to be weighed up with gold.
The sulphur fires, and a fine blue pigment is obtained.
A kind of vulcanite which contains a large proportion of vermilion or other mineral pigment is used, under the name of dental rubber, for making artificial gums and supports for artificial teeth.
It is chiefly used as a pigment and in the manufacture of flint glass.
The vermilion-like pigment which occurs in commerce as "chromered" is a basic chromate, Pb2Cr05, prepared by treating recently precipitated normal chromate with a properly adjusted proportion of caustic soda, or by boiling it with normal (yellow) potassium chromate.
The action of the sun's rays stimulates the cells of the skin to increase the pigment as a protection to the underlying tissues, e.g.
This pigment is of a light yellow colour, and contains a fatty substance that reacts to the fat-staining reagents.
The ' haemoglobin may be transformed into haematoidin, a pigment that does not contain iron, or into a pigment which does contain iron, haemosiderin.
The haematoidin pigment may vary in colour from yellowish or orange-red to a ruby-red, and forms granular masses, rhombic prisms or acicular crystals.
The absorption of these rays implies that the pigment absorbs radiant energy from the sun, and gives us some explanation of its power of constructing the carbohydrates which has been mentioned as the special work of the apparatus.
The composition of the pigment is quite similar to that of lapis lazuli; but the constitution of both is uncertain.
Of greater practical importance is a basic carbonate, substantially 2PbCO 3 Pb(OH) 2, largely used as a white pigment under the name of "white lead."
Lead chromate, PbCrO 4, is prepared industrially as a yellow pigment, chrome yellow, by precipitating sugar of lead solution with potassium bichromate.
In hepatogenous pigmentation (icterus or jaundice) we have the iron-free pigment modified and transformed by the action of the liver cells into bile pigment (bilirubin).
Various solvents, such as benzene, alcohol and chloroform, will dissolve out the pigment, leaving the plastid colorless.
The working of it is not at all completely understood at present, nor can we say exactly what is the part played by the pigment and what is the rfile of the protoplasm of the plastid.
6); and it has been suggested that the association of these two is analogous to the association of the rods and cones of the animal eye with their pigment layer, the light absorbed by the red pigment-spot setting up changes which react upon the refractive granule and being transmitted to the flagellum bring about those modifications in its vibrations by which the direction of movement of the organism is regulated.
Commercially, barytes is used in the preparation of barium compounds, as a body for certain kinds of paper and cloth, and as a white pigment ("permanent white").
Most of the rubber now manufactured is not combined with sulphur when in the form of sheets, but is mechanically incorporated with about one-tenth of its weight of that substance by means of the mixing rollers - any required pigment or other matter, such as whiting or barium sulphate, being added.
They are lined by cells charged with a yellow or brown pigment, and besides their excretory functions they act as ducts through which the reproductive cells leave the body.
This pigment is of great antiquity; Theophrastus called it kibOhov, and prepared it by acting on lead with vinegar, and Pliny, who called it cerussa, obtained it by dissolving lead in vinegar and evaporating to dryness.
When carbon dioxide is passed into this solution the whole of the added oxide, and even part of the oxide of the normal salt, is precipitated as a basic carbonate chemically similar, but not quite equivalent as a pigment, to white lead.
(x 75 diam.) pigment from the liver by the normal channels be prevented, as by obstruction of the main bile ducts, the bile will accumulate until it regurgitates or is absorbed into the lymph and blood vessels, and is carried in a soluble state throughout the tissues, thus producing a general staining - an essential characteristic of jaundice.
Zn(OK)2] Zinc oxide is used in the arts as a white pigment (zinc white); it has not by any means the covering power of white lead, but offers the advantages of being non-poisonous and of not becoming discoloured in sulphuretted hydrogen.
It is used as a pigment (cadmium yellow), for it retains its colour in an atmosphere containing sulphuretted hydrogen; it melts at a white heat, and on cooling solidifies to a lemon-yellow micaceous mass.
Pigment-cells, which are con, Otolith.
In the Algae such a cell consists essentially of: (1) a mass of protoplasm provided with (2) a nucleus and (3) an assimilating apparatus consisting of a colored protoplasmic body, called a chromatophore, the pigment of which in the pure green forms is chlorophyll, and which may then be called a cliloroplast.
Gibbula, with jaws, three pairs of epipodial cirri without pigment spots at their bases, British.
Clay tablets and discs (so far in Crete only), but nothing of more perishable nature, such as skin, papyrus, &c.; engraved gems and gem impressions; legends written with pigment on pottery (rare); characters incised on stone or pottery.
The more highly organized species have often very numerous eyes (Amphiporus, Drepanophorus), which are provided with a spherical refracting anterior portion, with a cellular " vitreous body," with a layer of delicate radially arranged rods, with an outer sheath of dark pigment, and with a separate nerve-twig each, springing from a common or double pair of branches which leave the brain as n.
ULTRAMARINE, a blue pigment, consisting essentially of a double silicate of aluminium and sodium with some sulphides or sulphates, and occurring in nature as a proximate component of lapis lazuli.
As early at least as the ith century the art of extracting a blue pigment from lapis lazuli was practised, and from the beginning of the 16th century this pigment began to be imported into Europe from "over the sea," as azurrum ultramarinum.
A, Diagram of a retinula of the central eye of a scorpion consisting of five retina-cells (ret), with adherent branched pigment cells (pig).
The one-sided specialization and the peculiar metallic colouring of the lateral tail feathers mark them as the extreme terms of a degenerative series, whilst the symmetry, likeness of constituent parts inter se, and absence of specialized pigment, as well as the fact that they differ little from any average feather of birds in general, mark the contour feather as primitively simple, and as the starting-point from which the highly elaborated eye-painted tail feather has gradually evolved.
Exposed to air this mixture is oxidized to the pigment uranium red, U6(NH4)2S09, which is a fine blood-coloured amorphous powder.
Trophic and nervous conditions sometimes cause localized deficiency of pigment which produces white areas in the skin.
In this case the pigment-cells are endodermal, forming a cup of pigment in which the visual cones are embedded.
The root differs from the shoot in the characters of its surface tissues, in the absence of the green assimilative pigment chlorophyll, in the arrangement of its vascular system and in the mode of growth at the apex, all features which are in direct relation to its normally subterranean life and its fixative and absorptive functions.
If a solution of the pigment is placed in the path of a beam of light which is then allowed to fall on a prism, the resulting spectrum will be found to be modified.
Cp, Pigment cells.
Margarita, five to seven pairs of epipodial cirri with a pigment spot at base of each.
These dorsal eyes are very perfect in elaboration, possessing lens, retinal nerve-end cells, retinal pigment and optic nerve.
Besides these more highly differentiated organs of vision, more primitive eyes are present in others down to simple stellate pigment specks without any refracting apparatus.
Sodium uranate, Na2U207, is used as a pigment for painting on glass and porcelain under the name of uranium yellow.
The blood suffers first; its pigment is dissolved out and soaks into the surroundings, imparting to them the pink hue so diagnostic of commencing gangrene.
Where pigment was present within the cells (sarcoma), the attraction-spheres were represented by quite clear unpigmented areas, sometimes with a centrosome in their midst.
VERMILION, a scarlet pigment composed of mercuric sulphide, HgS.
Haemosiderin, an iron-containing pigment (probably an hydrated ferrous oxide), is found in more or less loose combination with protein substances in an amorphous form as brownish or black granules.
Within the cytoplasm are found manifestations of functional activity, in the form of digestive vacuoles, granules, fat, glycogen, pigment, and foreign bodies.
This pigment is usually intracellular, but may be found lying free in the intercellular substance, and is generally in the form of fine granules of a yellowish-brown or brown-black colour.
The Melian earth (yrl M0Xc6.3) was employed as a pigment by ancient artists.