Of Vegetation. ^f 



expands) by the fponginefs of the pith, with- 

 out the help of valves. For 'tis very pro- 

 bable, that the particles of water, which im- 

 mediately adhere to, and are ftrongly im- 

 bibed into, and attracted by every fibre of 

 the fpongy pith, will fuffer fome degree of 

 expanfion, before they can be detach'd by the 

 fun's warmth from each attracting fibre ; and 

 confequently the mafs of fpongy fibres, of 

 which the pith confifts, muft thereby be 

 extended. 



And that the pith may be the more fer- 

 viceable for this purpofe, Nature has pro- 

 vided, in moft (hoots, a ftrong partition at 

 every knot ; which partitions ferve not only 

 as plinths or abutments for the dilating pith 

 to exert its force on, but alfo to prevent the 

 rarefied fap's too free retreat from the pith, 

 as well as for the ihooting forth of branches, 

 leaves and fruit. 



But a dilating fpongy fubftance, by equally 

 expanding itfelf every way, would not pro- 

 duce an oblong fhoot, but rather a globofe 

 one, like an Apple ; to prevent which incon- 

 venience we may obferve, that Nature has 

 provided feveral Diaphragms, befides thofe 

 at each knot, which are placed at fmall di- 

 ftances acrofs the pith, thereby preventing 



Z its 



