YOUNGER YEARS OF A PLANT. 187 



process, however, can only go on during daytime, as light 

 is indispensable and is performed by all the green parts 

 of a plant alike. It is this incessant labor which makes 

 plants not only an ornament of our earth and a food for 

 man and cattle, but renders them so eminently useful in 

 the great household of Nature. They absorb the carbon, 

 that man cannot breathe, and furnish, in return, the oxygen, 

 without which he cannot exist ; thus virtually, by their 

 industry, rendering the atmosphere fit for the support of 

 animal life. Besides the exhalation of oxygen, the leaves 

 also evaporate nearly two-thirds of the water which the 

 roots have imbibed, and sent up to them through the in- 

 terior of the plant. The moment this now perfectly pure 

 water is exhaled, it is dissolved in the air, and becomes 

 invisible to the eye. 



Another duty, which the leaves of plants perform with 

 still greater energy, is the drawing of water from the 

 atmosphere. They drink it in, from the first moment of 

 their short life, to the last day, by all possible means and 

 contrivances. The young leaves, as yet wholly or in part 

 rolled up, are but so many cups or spoons, turned to 

 heaven to gather all the moisture they can hold. As the 

 young plants grow, they unfold leaf after leaf, and all 

 perform the same duty with the same eagerness. From 

 the cedar of Lebanon down to the bashful violet, each 

 plant holds forth its gigantic mass of foliage or its tiny 

 goblet, to have its share of the precious moisture. A 

 glance shows us that leaves have generally a little canal 

 passing from the end up to their base, in which the water 

 they have gathered runs down ; and it has been observed 



