The Compte rendu du Congres de Botanique et d'Horticidture de 1880, contains a valuable paper by Professor Ed. Peynaert on this subject. He shews that the influence varies with the class of colors. In what gardeners would call the Blood-leaved class, high vital power had as much to do with color as light. The half starved leaves of a purple hazel or blood-leaved beech, are very early green, and the leaves of these, the Blood-leaved beech, and others, get green as they approach the "sere" of autumn. Also, it is well known that when a blood-leaved tree is transplanted, and its vital powers necessarily interfered with for a season or two, it has much paler leaves than when it becomes well established. This little fact has great practical value, for those who would have the richest color from their blood-leaved trees should feed them well. Golden colored leaves, as Golden Poplar, Golden Catalpa, Golden Geranium, are favored by diminished light. Glaucous colors, such as in Cedrus Deodo-ra, some forms of Lawson Cypress, etc. are favored by light generally; he has found a variety of Begonia, "Louise Chretien," to be an exception.

In this the glaucous color is favored by shade.