Among the terrors of our youth we well remember there were certain poisonous exhalations said to arise from plants and flowers if allowed to share our sleeping-room during the night, as though objects of loveliness when seen by daylight took advantage of the darkness to assume the qualities of the ghoul or the vampire. Well do we remember how maternal anxiety removed every portion of vegetable life from our bedroom, lest its gases should poison us before morning! This opinion, and the cognate one that plants in rooms are always injurious, is prevalent still, and it operates most unfavorably in the case of the bed-ridden, or the invalid, by depriving them of a chamber garden which would otherwise make time put off his leaden wings, and while away, in innocent amusement, many a lagging hour. Now we assure our readers that this is a popular superstition, and will endeavor to put them in possession of the grounds on which our statement is founded. In doing so, we do not put forth any opinions of our own, but the deductions of science, for the truth of which any one acquainted with vegetable physiology can vouch. Plants, in a growing state, absorb the oxygen gas of the atmosphere, and throw off carbonic acid; these are facts, and as oxygen is necessary to life and carbonic acid injurious to it, the conclusion has been jumped at that plants in apartments _must_ have a deleterious influence. But there is another fact equally irrefragable, _that plants feed on the carbonic acid of the atmosphere_, and are, indeed, the grand instruments employed in the laboratory of Nature for purifying it from the noxious exhalations of animal life. From the spacious forests to the blade of grass which forces itself up through the crevices of a street pavement, every portion of verdure is occupied in disinfecting the air. By means of solar light the carbonic acid, when taken in by the leaves, is decomposed, its carbon going to build up the structure of the plant and its disengaged oxygen returning to the air we breathe. It is true that this process is stopped in the darkness, and that then a very small portion of carbonic acid is evolved by plants; but as it is never necessary for a patient to sleep in a room with flowers, we need say nothing on that subject. Cleanliness, and other considerations, would suggest having a bedroom as free as possible during the night, and our object is answered if we show that vegetation is not injurious in the day. That it is, on the contrary, conducive to health, is a plain corollary of science.