OCR
COLOURS IN RIPPLED WATER 111 of purple? The fact that the resulting colour appears to be independent of the colour of the seaweed and to arise from any dark bottom, would point to its being also an effect of contrast. Moreover the pinkish colour seems to be more noticeable when looking obliquely, so that one is inclined to put it down, as in the case of the cloud shadows, to the surface-reflected light becoming tinged with the complementary of the surrounding colour. But there is much to be said on both sides of this difficult and complicated question.