ABSORPTION OF LEAVES. 145 



decidedly be of a morbid nature*. That wax is also 

 an exudation from the leaves of plants, appears from 

 the experiments recorded by Dr. Thomson in his Che- 

 mistry, 0. 4. 298, and it has been long ago assorted 

 that wax may easily be gathered from th,3 leaves of 

 Rosemary. On this subject I have not made any ex- 

 periments to satisfy myself. 



With respect to the absorbing power of leaves, the 

 best observations* that have been made are those of 

 Bonnet, recorded in the beginning of his Recherches 

 sur V Usage des Fcuilles. His aim was, by laying leaves 

 of various plants upon the top of a jar of water, some 

 with their upper, and others of the same species with 

 their under, surfaces applied to the water,- to discover 

 in which situation the leaves of each plant continued 

 longest in health and vigour, and also how far diffe- 

 rent species differed from each other in this respect. 

 The results were in many instances highly curious. 



Of fourteen herbaceous plants tried by this philoso- 

 pher, six lived nearly as long with one surface applied 

 to the water as with the other ; these were the com- 

 mon Arum maculatum, the French Bean, the Sun- 

 flower, Cabbage, Spinach, and the Small Mallow. By 

 the last I presume is meant Malva rotundi/blia, EngL 

 Bot. V. 1092. Six others, Plantain, White Mullein, 



* I do not mean to dispute the accuracy of Mr. Curtis's excellent 

 paper, Tr. of Linn. Soc. v. 6, written to prove honey-dew to be the 

 dung of Aphides. I only contend that there are more than one kind of 

 honey-dew. 



L 



