76 PBANTOM FLOWERS. 



carbonic acid, goes on. The leaves must not only be 

 exposed to the light, but their color must be green. 

 Such plants as have been grown in the dark are in- 

 variably feeble and destitute of strength and substance, 

 but they are also without color. This is owing to the 

 deficiency of carbon ; for while they may absorb car- 

 bonic acid from the air, the absence of sunshine pre- 

 vents them from separating it. When the leaves lose 

 their natural green color, it is evidence of disease. 

 The plant has in great measure lost its power of 

 digesting its food, and remedies must be resorted to 

 to remove the cause. The books abound in instances 

 of all descriptions of plants being thus affected, while 

 the remedial agencies are happily quite as numerous, 

 and in many cases entirely successful. 



Such are the powers of absorption possessed by the 

 leaves. Their capacity for giving off exhalations are 

 equally wonderful. Botanists have carefully measured 

 the extent of this exhalation in certain plants. An 

 Apple-tree, with twelve square feet of foliage, per- 

 spires nine ounces of water per day. A Vine of similar 

 dimensions exhaled from five to six ounces daily. A 

 Sunflower, three and a half feet high, was found to 

 perspire at the rate of twenty to thirty ounces of 



