THE LEAF. 35 



jecting bars often gradually depress themselves into a trans- 

 parent net of rivers. But the mechanical force of the framework 

 in carrying the leaf-tissue is the point first to be noticed ; it is 

 that which admits, regulates, or restrains the visible motions 

 of the leaf ; while the system of circulation can only be stud- 

 ied through the microscope. But the ribbed leaf bears itself 

 to the wind, as the webbed foot of a bird does to the water, 

 and needs the same kind, though not the same strength, of 

 support ; and its ribs always are partly therefore constituted 

 of strong woody substance, which is knit out of the tissue ; 

 and you can extricate this skeleton framework, and keep it, 

 after the leaf-tissue is dissolved. So I shall henceforward 

 speak simply of the leaf and its ribs, only specifying the ad- 

 ditional veined structure on necessary occasions. 



10. I have just said that the ribs and might have said, 

 farther, the stalk that sustains them are knit out of the 

 tissue of the leaf. But what is the leaf tissue itself knit out 

 of ? One would think that was nearly the first thing to be 

 discovered, or at least to be thought of, concerning plants, 

 namely, how and of what they are made. We say they 

 ' grow. ' But you know that they can't grow out of nothing ; 

 this solid wood and rich tracery must be made out of some 

 previously existing substance. What is the substance ? and 

 how is it woven into leaves, twisted into wood ? 



11. Consider how fast this is done, in spring. You walk 

 in February over a slippery field, where, through hoar-frost 

 and mud, you perhaps hardly see the small green blades of 

 trampled turf. In twelve weeks you wade through the same 

 field up to your knees in fresh grass ; and in a week or two 

 more, you mow two or three solid haystacks off it. In winter 

 you walk by your currant-bush, or your vine. They are 

 shrivelled sticks like bits of black tea in the canister. You 

 pass again in May, and the currant-bush looks like a young 

 sycamore tree ; and the vine is a bower : and meanwhile the 

 forests, all over this side of the round world, have grown 

 their foot or two in height, with new leaves so much 

 deeper, so much denser than they were. Where has it all 

 come from ? Cut off the fresh shoots from a single branch of 



