VEGETABLE PHYSIOLOGY. 83 



the phenomena of the temporary organs, and secondly, the 

 phenomena of the decay of the permanent organs and consequent 

 death of the plant. 



Decay of the Temporary Organs. 



The decay of the temporary organs which takes place annually 

 is a phenomenon familiar to every body, and comprehends the fall 

 of the leaf, the fall of the flower and the fall of the fruit. 



1. The fall of the leaf. The fall of the leaf, or annual 

 defoliation of the plant, commences for the most part with the 

 colds of the autumn, and is accelerated by the frosts of winter, 

 that strip the forest of its foliage, and the landscape of its verdure. 

 But there are some trees that retain their leaves throughout the 

 whole winter, though changed to a dull and dusky brown, as 

 those of the beach tree ; and there are others that retain them 

 even in verdure till the succeeding spring, when they ultimately 

 fall. Such plants are denominated evergreens. 



It was at one time indeed a vulgar error,^ and perhaps it 

 continues to be so still, that evergreens never shed their leaves 

 at all. This error may be traced back even to the period of the 

 fabulous history of the Greeks, with whose mythology it was 

 closely interwoven, at least in one particular example as related 

 by Theophrastus ; who says that in the country of Cortynia, in 

 Crete, it was reported there was a plane tree growing by a 

 fountain which never shed its leaves, being the tree under the 

 shade of which Jupiter was said to have had his interview with 

 Europa. But Theophrastus was himself acquainted with the 

 fact of the fall of the leaves of evergreens, as every accurate 

 observer of nature must be, though they do not actually fall till 

 the young leaves have begun to appear, so that trees of this sort 

 are never left wholly without leaves, which it was hence supposed 

 they never shed. In warm climates it is said that many plants 

 retain their leaves for several years ; but in temperate and polar 

 climates there are no such plants to be found. 



Such is the fact of the annual fall of the leaves. What is the 

 cause of their fall ? The solution of this question seems to have 



