While such minute and gradual variations are harmless for most optical purposes, sudden variations which generally take the form of striae or veins are fatal defects in all optical glass.
With changes of the pressures of the blood in arteries, veins or capillaries, and in the heart itself and its respective chambers, static changes are apt to follow in these parts; such as degeneration of the coats of the arteries, due either to the silent tooth of time, to persistent high blood pressures, or to the action of poisons such as lead or syphilis.
His face was livid, the veins standing out on his neck.
A moment later, veins of light threaded through dark low clouds.
It occurs in its matrix, either in or closely associated with fissure veins or disseminated through rock masses.