12 EXAMINATION OF [CHAP. 



lying upon the table. No. 2 was placed with its root in 

 water. No. 3 was hung upside down, with a flower or 

 leaf in water, the root in the air. 



The general result of your experiment will be as fol- 

 lows : After the lapse of, say, twenty-four hours or so, 

 No. i will be, as we have already found, faded ; No. 2 

 will be nearly unaltered ; No. 3 will be partially faded, the 

 parts out of water especially. Hence we may gather that 

 water supplied to the specimens prevents them from fading, 

 especially if it be supplied to the root. On the other 

 hand, if water be withheld, they fade. 



2. If we take now the faded specimen first described 

 and put its root in water, and leave it for a few hours in 

 a cool, shaded room, we shall probably find, unless it be 

 irretrievably withered, that it freshens more or less, the 

 leaves and stem, recovering their tension, become firmer 

 and more nearly like their original state. 



This experiment shows us, further, that water supplied 

 to a fading buttercup enables it to recover. 



Reflecting upon these experiments, we shall be led to 

 the following conclusions : 



i. That water evaporates from the exposed surface of 

 plants. 



ii. That fresh supplies are taken into the plant by the 

 root. 



iii. That the stem serves to convey this water-supply 

 from the root to the leaves. 



3. We may now try another simple experiment, devised 

 by Professor Henslow, which shows that exposure to 

 direct sunlight has an almost immediate influence upon 

 the amount of this evaporation of water from the leaves. 

 Take six or eight of the largest, healthy, radical leaves of 

 the buttercup you can find ; two tumblers filled to within 

 an inch of the top with water, two empty, dry tumblers, 

 and two pieces of card, each large enough to cover the 

 mouth of a tumbler. In the middle of each card bore 

 two or three small holes just wide enough to allow the 

 petiole of a leaf to pass through. Let the petioles hang 

 sufficiently deep to dip into the water when the cards are 

 put upon the tumblers containing it. Having arranged 

 matters thus, turn the empty tumblers upside down, one 

 over each card, so as to cover the blades of the leaves. 



