THE LEAVES. IO3 



between the eye and the light, two parts become evident: 

 (i) a green tissue, more or less opaque ; and (2) translu- 

 cent '' nerves " or " veins." * The larger of these, usually 

 called the ' ' ribs, ' ' * frequently form ridges upon the under 

 surface. 



Fig. 95. -A shoot of Acacia,^^o^vD.% at « a twice-branched (compound) leaf with 

 roundish petiole ; at ^, a similar leaf with flattened blade-like petiole ; at c, phyllodia, 

 i.e., blade-like petioles without true blades. About half natural size (?)— .4fter Frank. 



128. Branching. — The outline of the blade is extremely 

 various. It is dependent upon the character and extent of 

 its branching, which may be either slight or extensive. 

 Slight branching gives rise to teeth of various forms (fig. 96). 

 More profound branching is evident in divided or parted 

 leaves (fig. 97). In some blades the branching is so exten- 

 sive and complete that the green tissue no longer fills the 



* These words must not be thought to indicate any resemblance in 

 function to the same parts in animals, but only similarity of position or 

 appearance. 



