3 5 i 0/ Vegetation. 



no farther ufe, do periflij not only becaufe 

 the now grown and more expanded leaves 

 of the young plant or tree do fo over-fhadow 

 the fupplemental leaves, that their former 

 more plentiful perfpiration is much abated, 

 and thereby alfo their power of attracting fap 

 fails ; but alfo, becaufe the fap is drawn from 

 them by the leaves, and they being thus de- 

 prived of nourimment, do perifh. 



As the tree advances in ftature, the firft, 

 fecond, third, and fourth order of lateral 

 branches {hoot our, each lower order being 

 longer than thofe immediately above them ; 

 not only on account of primogeniture, but 

 alfo, becaufe being inferted in larger parts of 

 the trunk, and nearer the root, they have the 

 advantage of being ferved with greater plenty 

 of fap, whence arifes the beautiful parabo- 

 lical figure of trees. 



But when trees ftand thick together in 

 Woods or Groves, this their natural fhape is 

 altered, becaufe the lower lateral branches 

 being much fhaded, they can perfpire little ; 

 and therefore drawing little nourifhment, 

 they perifh ; but the top branches being ex- 

 pofed to a free drying air, they perfpire plen- 

 tifully, and thereby drawing the fap to the 

 top, they advance much in height : But vice 



versa, 

 5 



