In some cases the plastid disappears and the crystalline pigment only is left.
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.
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.
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.
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.
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.
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 ' 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.
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.
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.
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").
The pigment is also principally localized in this layer, although sometimes it is present even deeper down within the musculature.
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.
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.
In addition to its brilliance, vermilion is a pigment of great intensity and durability, remaining unaffected by acid fumes.
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.
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 composition of the pigment is quite similar to that of lapis lazuli; but the constitution of both is uncertain.
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.
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.
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.
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.
Trophic and nervous conditions sometimes cause localized deficiency of pigment which produces white areas in the skin.
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.