v.] HORSE CHESTNUT. 109 



would be far smaller than it is at present. Again, if 

 we compare the thickness of an average Sycamore 

 stem below the sixth leaf, with that of a Beech stem, 

 it is obvious that there would be a considerable waste 

 of power. Once more, if the leaves were parallel to 

 the branch, they would, as the branches are arranged, 

 be less well disposed with reference to light and air 

 A glance at Figs. 6^, 68, and 69, however, will show 



Fig. 68.— Horse Chestnut. 



how beautifully the leaves are adapted to their 

 changed conditions. The blades of the leaves of the 

 upper pair form an angle with the leaf-stalks, so as to 

 assume a horizontal position, or nearly so ; the leaf- 

 stalks of the second pair decussate with those of the 

 first, and are just so much longer as to bring up that 

 pair nearly, or quite, to a level with the first; the 

 third pair decussate with the second and are again 



