i<*8 The Statural Hiftory 



Jiculties, and no queftion will fatisfie all unprejudiced Readers 

 how our tree comes to flourish, though difbark'd all round. 



72. But if there fhall be any found fo fro ward, as not to al- 

 low(againft all experience) thofe minute fap veffels in the fubftance 

 of the wood, yet the vifible pricked circles between the annual coats 

 of the wood r , obferved alfoby Uv.lfillughby, Mr. Ray, and Dr. 

 Tong % which I fuppofe may be the large air veffels of Dr. Grew, 

 may be fufficient for this purpofe ; efpecially in Elm, where they 

 are numerous and of two forts, as in Tab. ro. Fig. 2. I K, &c. 

 rs, is"C It being the office of air veffels, for about a month in March 

 and ApriV, before the new Jap veffels of the ZwAare fit for ufe, to 

 convey the fap neceffary for the vegetation of all Plants. And if 

 fo, in old trees that have done growing, and have no need of the 

 annual new production of a bark.-, why may it not continually a- 

 fcend by them frill ? 



73. To which if it be objected, that a tree lives as well by ve- 

 getable air zsfap, and that if the air veffels be continually fill'd with 

 fap, the tree muft dye on the other fide for want of air : It may 



eafily be reply ed, that the ufe of the Infertions or Diametral por- 

 tions t Fig. 2. X Y, interceding the pith at T V W, and the paren- 

 chyma of the bark, at G H, all made of fmall kind of bladders 

 clufter'd together, is for conveyance of air, as well as the air 

 veffels themfelves. But if it be further urged, that the Diame- 

 tral portions only ferve to convey it by the bredth, and not the 

 length of the tree, which makes them inefficient for this pur- 

 pofe ; we have latitude enough, and can allow the lefftr fap vef- 

 fels that lye in crofs bars at r s to fupply that defect, and ftill re- 

 tain all the ranges of the great air veffels at IK, LM, NO, PQ , for 

 conveyance of the fap, in fuch like Trees as our old Elm. 



74. And if it be further enquired, how it comes to pafs that 

 fome trees do dye upon the lofs of their bark, and all are not pre- 

 ferved by the help of the fap, or air veffels of the wood : It may 

 be anfwer'd, and probably rightly enough, that fuch trees as are 

 young, a growing, have a plentiful ifTue of x\\\nfap between the 

 bark, and the wood, and that readily bleed when they are wound- 

 ed or bored, do moft commonly (if not always) certainly dye: 

 whereas fome of the fame trees when older, pad growing, efpe- 

 cially if they have a more gummy juice, fuch as Afi, Elm, Lime- 



* Philofoph. Tranfaft. tJumi. 43. ^48. Dr. Grew of the vegetation of Plantsj cap. 1. 



tree, 



/ 



