Blanching, or etiolation, is effected by making plants grow in the dark, and the more completely the light is excluded the more entire is the absence of colour from the leaves and stems of the plants. The colouring matter of these is entirely dependent upon their power to decompose water and carbonic acid gas, a power they do not possess when light is absent. The effect of blanching is to render the parts more delicately flavoured, more pleasing to the eye, and more crisp, properties very desirable in sea kale, celery, rhubarb, endive, lettuces, etc. Wherever it can be accomplished, blanching pots should be employed, in preference to covering the plants with earth or other materials. The flavour is better, and decay is less liable to be induced. Lettuces and cabbages are usually whitened by tying the leaves over the heart or centre bud, but even in these instances the blanching pot operates much more effectually. In remote country places blanching pots may not be readily obtained; an equally useful aid is found by placing together two boards of a convenient length, so as to form as it were two sides of a triangle, or double pitched roof.