THE LEAF 157 
175. Veins as water carriers. — Examine a leaf from a 
stem that has stood in red ink for an hour or two. Do you 
see evidence that it has absorbed any of the liquid? Cut 
across the blade and examine with a lens. What course has 
the absorbed liquid followed? What use does this indicate 
for the veins, besides the one already noted? Observe tha 
point of insertion on the stem, and examine the scar with a 
lens: do you see any evidence of a connection between the 
leaf veins and the fibrovascular bundles of the stem? (111, 
125, 126. Notice where and how the veins end. Are they 
“of the same size all the way, or do they grow smaller toward 
the tip? Are they separate and distinct, or are they con- 
nected throughout their ramifications, like the veins and 
arteries of the human body? How do you know? Do you 
see any of the coloring fluid in the small reticulations be- 
tween the veins? How did it get there? 
176. The nature and office of veins.— We learn from 173 
and 175 that the veining serves two important purposes in the 
economy of the leaf: first, as a skeleton or framework, to sup- 
port the expanded blade; and second, as a system of water 
pipes, for conveying the sap out of which its food is manu- 
factured. In other words the veins are a continuation of the 
fibrovascular bundles into the leaves, by means of which the 
latter are put in communication with the body of the plant. 
177. The relation between veining and lobing. — Com- 
pare the outline of a leaf of maple or ivy with one of oak or 
chrysanthemum. Do you perceive any correspondence be- 
tween the manner of lobing or indentation of their margins, 
and the direction of the veins? (Figs. 210, 211.) To what 
class would you refer each one? 
The lobes themselves may be variously cut, as in the 
fennel and rose geranium, thus giving rise to twice-cleft, 
thrice-cleft (Fig. 212), four-cleft, or even still more in- 
tricately divided blades. 
178. Compound leaves. Compare with the specimens 
just examined a leaf of horse-chestnut, clover, or Virginia 
