220 AUTUMNAL LEAVES. 



between them have turned yellow or red or orange 

 or purple. 



The venation of the Ivy is very elaborate and 

 beautiful. The form of the leaf is marvellously 

 varied, though rarely departing from the three- 

 lobed or five-lobed form, but the rounding or 

 elongation of the lobes is very various in different 

 individuals. A principal vein runs from the apex 

 of the leaf -stalk through the centre of each lobe, 

 and from these veins the forking and branch- 

 ing of the veinlets is very elaborate, resembling 

 indeed very much the contorted and twisted rami- 

 fication of the Oak. 



It is upon the upper surfaces of the Ivy leaves 

 that the most beautiful tints are to be seen, and as 

 it is the upper surfaces which are exposed to the 

 sunshine the circumstance furnishes another proof 

 that it is to the action of sunlight upon the 

 chemical substances contained in the superficial 

 plant cells that is due the marvellous hues which 

 contribute to the splendour of Autumn. 



