LEAF-ARRANGEMENT. 97 



in wreaths, endlessly expressive, deceptive, fan- 

 tastic, never the same from footstock to blossom, 

 they seem perpetually to tempt our watchfulness 

 and take delight in outstripping our wonder." 



Now, why is this marvellous variety, this inex- 

 haustible treasury of beautiful forms ? Does it 

 result from some innate tendency of each species ? 

 Is it intentionally designed to delight the eye of 

 man ? Or has the form, and size, and texture 

 some reference to the structure and organization, 

 the habits, and requirements, of the whole plant ? 



I do not propose now to discuss any of the 

 more unusual and abnormal forms of leaves ; . . . 

 I propose, rather, to ask you to consider the struc- 

 ture, and especially the forms, of the common, 

 every-day leaves of our woods and fields. . . . 



In the first place, let us consider the size of the 

 leaf. On what does it depend? In herbs we 

 very often see the leaves decrease towards the end 

 of the shoot; while in trees the leaves, though 

 not identical, are much more uniform in size. 



Again, if we take a twig of Hornbeam, we shall 

 find that the six terminal leaves have together an 

 area of about 14 square inches, and the section of 

 the twig has a diameter of .06 of an inch. In the 

 Beech the leaves are rather larger, six of them 



