As one works with color in a practical or experimental way, one is impressed by two appare

ntly unrelated facts. Color as seen is a mobile, changeable thing (1)_____ to a large extent on the relationship of the color (2)_____ other colors (3)_____ simultaneously. It is not (4)_____ in its relation to the direct stimulus which (5)_____ it. On the other hand, the properties of surfaces that give (6)_____ to color do not seem to change greatly under a wide variety of illumination color, usually (but not always) looking much the same in artificial light as in daylight. Both of these effects seem to be (7)_____ in large part to the mechanism of color (8)_____.

When the eye is (9)_____ to a colored area, there is an immediate readjustment of the (10)_____ of the eye to color in and around the area (11)_____. This readjustment does not promptly affect the color seen but usually does affect the next area to which the (12)_____ is shifted. The longer the time of viewing, the higher the (13)_____, and the larger the area, the greater the effect will be (14)_____ its persistence in the (15)_____ viewing situation. As indicated by the work of Wright and Schouten, it appears that, at (16)_____ for a first approximation, full adaptation takes place over (17)_____ time if the adapting source is moderately bright and the eye has been in (18)_____ darkness just previously. Also, (19)_____ of the persistence of the effect if the eye is shifted around from one object to another, all of which are at similar brightness or have similar colors, the adaptation will tend to become (20)_____ over the whole eye.

A．liable

B．focusing

C．typical

D．depending