140 PRINCIPLES OF GARDENING. [cH. IV. 



'20 ozs., were allowed to vegetate without their leaves 

 being cleansed for a whole twelvemonth ; and two 

 others, weighing 19 and 20 1 ozs. each, had their 

 leaves sponged mth tepid water once a week; the 

 two first increased in weight less than half an ounce 

 each; whilst of the two latter, one had increased 

 two, and the other nearly three ounces. In all other 

 respects they had been treated similarly. 



It must be remembered, however, in using the 

 sponge and the syringe, that the under side of leaves 

 is an absorbing surface, benefited by being kept 

 clean, and by the application of moisture. The kid- 

 ney bean, sunflower, cabbage, and spinach, absorb 

 moisture equally by their under and upper surfaces ; 

 the cockscomb, pui'ple-leaved amaranth, heliotrope, 

 lilac, and balm, absorb most freely by their upper 

 surfaces ; and the vine, pear, cheriy, apricot, walnut, 

 mulberry, and rose, absorb most by their under sur- 

 faces. 



The transpiration from the leaves of plants is ef- 

 fected through pores or stromates, varying in number 

 and size in every species, but being, usually, either 

 largest or most numerous in plants inhabiting moist 

 or shady localities. This is a wise provision ; for 

 such plants, consequently, have an abundant supply 

 of moist food to their roots, requiring a competent 

 provision for its elaboration and reduction from su- 

 perfluous water. Those plants which are natives of 



