cn. rr. 



<:jourse op the sap. 



47 



branch were cut in full leaf, and suspended from those 

 among which it grew, it should remain alive till the fall 

 of the leaf ; or when trees were cut down at midsum- 

 mer, till the fall of the leaf the heads would remain 

 alive, and the roots would immediately die. The 

 reverse of this is the case ; the roots remain alive, and 

 shoot out without any assistance from the atmosphere, 

 and the heads immediately die. 



If leaves are picked, they will die sooner than if 

 the bough is cut on which they stand ; if the bough is 

 cut, they will fade sooner than if the stem is cut on 

 which the bough stands ; and if the stem is cut, they 

 will fade sooner than if the tree is grubbed. All this 

 shows that the leaf is fed from the stem, and contra- 

 dicts Liebig's notion, that leaves feed themselves and 

 their parent trees from the atmosphere. 



Cut a branch in a hot sun in June or July. In 

 a few minutes its leaves will fade, dry, and shrivel. 

 What keeps their living brethren fresh and succulent 

 through the fifteen hours' drought and heat of our 

 midsummer sun ? A constant supply of sap from the 

 roots. If, indeed, a drought in summer or autumn is 

 continued so long as to deprive the roots of moisture, 

 the leaves will begin to fade ; but the leaves will 

 recover immediately, if the roots only are watered. 

 Doubtless, if the leaves also are watered, and wetted 

 hay-bands applied to the stems, it will expedite matters. 

 For doubtless plants absorb from all parts which are 

 exposed to moisture, and excrete, that is, transpire, or 



