Page:An introduction to physiological and systematical botany (1st edition).djvu/220

190 That wax is also an exudation from the leaves of plants, appears from the experiments recorded by Dr. Thomson in his Chemistry, v. 4, 298, and it has been long ago asserted that wax may easily be gathered from the leaves of Rosemary. On this subject I have not made any experiments 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 l'Usage des Feuilles. 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 different species differed from each other in this respect. The results were in many instances highly curious.

Of fourteen herbaceous plants tried by this