like a veil. It only disappeared by rubbing the eye for some time.
126.
Scherfer observes that the red colour, which is the consequence of a powerful impression of light, may last for some hours.
127.
As we can produce an appearance of light on the retina by pressure on the eyeball, so by a gentle pressure a red colour appears, thus corresponding with the after-image of an impression of light.
128.
Many sick persons, on awaking, see everything in the colour of the morning sky, as if through a red veil: so, if in the evening they doze and wake again, the same appearance presents itself. It remains for some minutes, and always disappears if the eye is rubbed a little. Red stars and balls sometimes accompany