UNCLE IN ENGLAND. 299 



of the leaf has been a subject of great curiosity 

 to me, and I felt quite sure that he could explain 

 the cause clearly. But he told me that it has 

 never been satisfactorily accounted for, and that 

 there is some objection to every opinion yet 

 published. He says it would be a very good 

 pursuit for my cousins arid myself, to begin a 

 course of observations on the nature of leaves 

 and leaf-buds, and their connexion with the 

 stem ; and he has offered a prize, as he says 

 they do in the learned societies, to whichever 

 amongst us takes the best view of the subject. 



I asked, was it not caused by frost ? " It is not 

 always the effect of autumnal frost," he replied. 

 " Some trees seem to lose their leaves at stated 

 times, independently of the temperature. They 

 fall from the lime, for instance, before any frost 

 happens ; and indeed all deciduous leaves, as 

 the season advances, become gradually more 

 rigid, less juicy, lose their down, and at last 

 change their healthy green colour to a yellow or 

 reddish hue. 



He then asked me if I had observed anything 

 of the order in which the different trees cast 

 them. I answered that the walnut and horse- 

 chesnut appeared to have lost their leaves before 

 any other : then the sycamore and lime, and I 

 believed the ash had soon followed; but that 

 many of the elm, and most of the beech and 



