68 FIRST STUDIES IN PLANT LIFE 



Composition Exercise. — Tell how the plant stores up sun- 

 foree, and how by sun-force a pony can run, and by sun-force you 

 <!an ride on its back. 



Note. — A distinction should be made between the bodily force and the 

 spirit force of a man. We cannot trace a man's spirit force to the sun ; nor, 

 indeed, can we explain any form of life force by physical causes alone. 



Drawing Exercise. — Draw the fruit of a vegetable marrow 

 when it is just forming, and, alongside of it, a full grown marrow- 

 fruit. Mark the dates, so as to shew how quickly the marrow 

 ^ows. 



XII.— THE LEAVES.— Part IV. 



Shapes and Vein-plans. 



1. Now that we know what leaves have to do for 

 the plant, we can go on to look at the form that leaves 

 take. And the first part to look at is the stalk of the 

 leaf. 



2. The leaf-stalk- The leaf-stalk may be long, 

 "when it is necessary to hold the blade well out into 

 light ; or it may be short, when this is not needed. 

 Again, the leaf-stalk is strong when the blade is hea\'j", 

 or slight when the leaf is light. Where the blade is 

 heavy the stalk may have a broad, firm hold upon the 

 stem, or may even clasp the stem. Look how a 

 rhubarb stalk clasps the stem, and you will see how a 

 great blade is supported. Examine a number of leaf- 

 stalks and you will find that they are rarely romid. 

 Often, as in the violet, they have two ridges that form 

 a channel or groove. Why is this ? If you look at 

 the girders that are used for supporting buildings, you 

 will see that we have copied this plan of Nature. We 



