THE NATURE OF TRANSPIRATION 



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duced under the receiver, and the branch is transferred 

 from the water to a watery solution of eosin. A wooden 

 screen is set to cut off the direct radiation of the beaker 

 from the branch. These arrangements are made in a 

 dull light, and, when complete, the whole is set in total 

 darkness. 



As soon as the beaker containing the hot water is intro- 

 duced under the receiver, the space included will immedi- 

 ately be filled with cloud and water vapour. Water is 

 freely deposited on the walls of the receiver and on the 

 surfaces of the leaves of the plant. The space is com- 

 pletely saturated, and remains so, as it continues to fall 

 in temperature, owing to the 

 gradual cooling of the whole ; 

 and, as the water is always 

 at a higher temperature than 

 the leaves, a constant distil- 

 lation goes on from the 

 beaker to the leaves. The 

 arrangements are shown in 

 Fig. 2. 



When these arrangements 

 have been made, the ap- 

 paratus is left for one hour. 



At the end of this time, it will be found that the eosin 

 solution has been drawn up very markedly into the plant, 

 thus showing that the elevation of the water in the 

 conduits may be effected by vital action. For in this 

 experiment the immediate energy relations of the' plant to 

 its surroundings cannot account for the rise. I have 

 performed this experiment, obtaining the same result, with 

 Chrysanthemum sinense, C. lacustre, Myrtus communis, 

 Eucalyptus globulus, Escallonia macrantha. 



As we should expect, it was found that, when dead leaves 

 and branches were set in this saturated chamber, no rise 

 of the eosin was observed, although simultaneously eosin 



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Fig. 2. 



