24 
THE FIRST BOOK OF BOTANY. 
EXERCISE II. 
Venation . 
You already know by name, and can point out, the 
parts of a leaf. By use yon will soon easily remem¬ 
ber these names. You have learned the names of 
hundreds and hundreds of things, by hearing others 
use them, and by using them yourself. Knowing the 
name of a thing is not knowing much about it, to be 
sure; but we must know its name if we are going to 
talk and write about it. There are a great many 
different parts in plants, and a great many new words 
will be needed in their study; but when you are 
looking at them, and talking and writing about them, 
you will learn their names without effort. 
There is a great deal to be seen in leaf-blades. 
Hold up a leaf between your eye and the light; you 
see it covered over with line lines, and it has also a 
few coarser lines running through it. Break one of 
the coarser ones and examine it. Is it woody ? Is it 
hollow ? These lines are called veins, and all of them 
taken together are spoken of as the venation of the 
leaf. You see that the spaces between these lines are 
all filled in with green matter. In some strong-veined 
leaves this matter can all be dissolved, leaving the 
veins just as they are now, but naked. 
Find where the largest veins begin and end. 
Where do the finer lines begin and end? Are there 
more than two sizes of veins ? 
You will need names for these different-sized 
veins. The largest are called ribs, the branches from 
the ribs are called veins, and the smallest are called 
yeinlets. (See Figs. 6 and 7.) Put by themselves 
