FALL OF THE LEAF. 26r 



seems so simple and evident, as to be hardly worth insist- 

 ing upon. Yet I find myself anticipated in this theory 

 by one physiologist only, named Vrolick, cited by 

 Willdenow in his Principles of Botany, p. 304, though 

 several learned speculations to no purpose are extant on 

 the subject. It is but just, however, that I should re- 

 late what led me to consider the matter with any atten- 

 tion. My observing friend Mr. Fairbairn of Chelsea 

 garden long ago remarked to me, that when he had oc- 

 casion to transplant any tree or shrub whilst in leaf, he 

 could soon judge of its success by the ease with which 

 its leaves were detached. The consequence of such 

 treatment is more or less injury to the health .of the 

 plant, as will first appear by the drooping of the leaves, 

 most of which will probably die, and the decay will 

 generally be extended to the younger more delicate 

 twigs. The exact progress of this decay may speedily 

 be known, bv the leaves of those branches which are ir- 

 recoverably dying or dead, remaining firmly attached, so 

 as not to be pulled off without a force sufficient to bring 

 away the bark or buds along with them : whereas the 

 leaves of parts that have received no material injury, and 

 where the vital energy acts with due power, either fall off 

 spontaneously, or are detached by the slighest touch. 

 Plants of hot countries, kept in our stoves, exhibit the 

 same phoenomenon when transplanted or otherwise in- 

 jured, even though not naturally deciduous. 



So when fruits are thoroughly ripened, they become, 

 with respect to the parent plant, dead substances, and, 

 however strongly attached before, are then thrown off as 

 extraneous bodies. Their stalks fiide or wither, though 



