FOLIAGE. I 5 5 



weather, as it draws towards the hottest time of the 

 afternoon, its leaves move into the regular sleeping 

 position. Even in ordinary weather, and in the 

 course of the day, leaves are scarcely ever in the same 

 position. Slight movements take place which alter the 

 inclination of the surface as the light shifts. The 

 moisture in the air makes a distinct difference in the 

 freshness of the leaf and its angle to the stalk. The 

 point of the leaf describes irregular elliptic movements, 

 greatly altered by the slight winds, which are scarcely 

 ever absent in this country. 



Towards autumn, there are signs that the leaf is 

 becoming stiff and old. Its movements become more 

 and more sluggish, and at last they cease to be 

 perceptible. Changes of a very complex character, 

 thereupon, begin in all deciduous leaves. Everything 

 that can possibly be utilised by the plant is sent 

 back to the stem, to be stored up in the form of 

 starch, oils, fatty substances, etc., for use next spring. 

 The chlorophyll breaks up ; sugars, plastic matters, 

 tannins, etc., disappear from the leaf, which is now a 

 mere framework of cells, and of various fibrous 

 matters which cannot be utilised. 



Whilst these changes are taking place, the leaves 

 show the exquisite autumn tints with which everyone 

 is familiar. The red anthocyanin again appears, and, 

 according to the character of the acids which are 

 present in the leaf, gives a violet, red, or blue colour. 

 These colours are not the same in every part of the 

 country; and trees seem even to have an individuality 

 of their own. Particular individuals frequently show a 

 much deeper tint than others of the same species. The 

 Rowan turns a brown or scarlet; the Birch becomes a 

 delicate yellow ; the Oak brownish yellow ; the Alder 



