180 Chapters in Modern Botany CHAP. 



pervade its whole interior, while at the same time it fur- 

 nishes ample accommodation to the chlorophyll grains, on 

 its long walls, where they have the best opportunity to 

 come into contact with the carbonic acid in the air- 

 passages." 



This compromise the student may now himself elaborate, 

 but also criticise afresh, so working towards familiarity 

 with the subject. 



Shapes of Leaves. " The leaves of the herbage at 

 our feet," Mr. Ruskin says, "take all kinds of strange 

 shapes, as if to invite us to examine them. Star -shaped, 

 heart - shaped, spear - shaped, arrow - shaped, fretted, fringed, 

 deft, furrowed, serrated, sinuated, in whorls, in tufts, in 

 spires, in wreaths, endlessly expressive, deceptive, fantastic, 

 never the same from foot of stalk to blossom, they seem 

 perpetually to tempt our watchfulness and take delight in 

 outstripping our wonder." 



We do not propose to describe these different forms of 

 leaves, nor to introduce the elaborate nomenclature which is 

 used in order to describe them with precision ; from the 

 present standpoint it is sufficient to give a few illustrations 

 showing how peculiar forms are adapted to special condi- 

 tions, referring the student for details to Sir John Lubbock's 

 Flowers, Fruits, and Leaves (Nature Series, Lond. 1888). 



Large and free-growing plants which obtain unobstructed 

 light most frequently bear simple or slightly lobed leaves, 

 while the smaller vegetation generally produces leaves either 

 long, simple, and narrow, as in grasses, or highly compound, 

 with small leaflets, as in ferns and many plants of the 

 woods and hedgerows, so as to seize as many as possible of 

 the broken sunbeams which have not been intercepted by 

 the loftier plants, while casting as little shadow as possible 

 upon each other. As the same amount of leaf material has 

 a greater surface when cut up than when forming a con- 



