1068. Leaves are the most important of all vegetable organs, serving at once for respiration, digestion, and nutrition. If a plant is deprived of its leaves before the fruit has commenced ripening, the fruit will full off without arriving at maturity ; and a branch deprived of its leaves for a whole summer, will either die or not increase in size. Most of the chemical changes effected in the sap take place in the leaves under the influence of solar light. It is true that leaves appear to decompose water, without the agency of light, solely by their vital force ; but the functions of respiration, perspiration, and digestion cannot be fully performed without the aid of solar light, and unless they are, the plant cannot be in vigorous health.