Of Dark Leaves in Front of Transparent Ones.
When the leaves are interposed between the light and the eye, then that which is nearest to the eye will be the darkest, and the most distant will be the lightest, not being seen against the atmosphere; and this is seen in the leaves which are away from the centre of the tree, that is towards the light.
[Footnote: See Pl. XXVIII, No. 2, the lower sketch.]
434.