One of the most successful cold graperies near Philadelphia, is said to have every third section of lights made entirely of blue glass. It is an important fact worthy of the special notice of our florists, gardeners and amateur horticulturists, that colored glass docs affect very materially the growth of vegetation beneath. More than ten years ago, Mr. R. Hunt, Secretary of the Royal Polytechnic Society, England, said: " The light which permeates colored glass partakes to some considerable extent of the character of the ray which corresponds with the glass in color; thus blue glass admits the chemical rays to the exclusion, or nearly so, of all others; yellow glass admits only the formation of the luminous rays, while red glass cuts off all but the heating rays, which pass it freely. This affords us a very easy method of growing plants under the influence of any particular light which may be desired. The fact to which I wish to call particular attention is, that the yellow and red rays are destructive to germination, whereas under the influence of violet, indigo, or blue lights, the process is quickened in a most extraordinary manner; indeed, it will be found that at any period during the early life of a plant, its growth may be checked by exposing it to the action of red or yellow light".