12 On the MO TlO N of 



COR. 4. Hence we find, that a tree does not become fuddenly re- 

 plete with fap, as has been generally thought. The fap does 

 not mount into a tree by one, but by feveral fucceflive tides. 

 The moft copious of all thefe, and the mod remarkable, is 

 that which brings on the bleeding. It is this tide, whofe pro- 

 grefs we trace in the prefent experiment ; but it is evidently pre- 

 ceded by feveral lefTer ones, which communicate a moifture 

 to the tree, though not in fuch quantity as to bleed. 



THAT a degree of fap afcends in trees immediately upon the fal- 

 ling of their leaves, appears from the vegetation of catkins, 

 during winter, upon the birch, the alder, and the hazel. But 

 in autumn, the trees are left fo devoid of fap, by the expence 

 of the former fummer and the fall of the leaf, that it is not 

 till fpring, and the return of a fufEcient degree of heat, that 

 they become fo impregnated with fap as to be capable of 

 bleeding. 



MARCH 20. 



Thermometer, at noon, 44. ; at midnight, 43. 

 THE fifth incifion bled, and thofe below it ; but the fixth, 



which had bled the day before, and all above it, were dry. 



EXP. 4. On this day, and on feveral other occafions, an incifion 

 made on the fouth fide of the tree bled always more plen- 

 tifully than an incifion at the fame height on the north fide. 



COR. 5. The ligneous circles in the trunks of trees are common- 

 ly eccentric, the centre of the circles being placed at a diftance 

 from the centre of the tree. M. DU HAMEL afcribes this ec- 

 centricity to the cafual infertion of roots, and the irruption of 

 branches, which determines the fap to move in greater abun- 

 dance on one fide of the tree than another. And it is unque- 

 ilionable that this fometimes happens. But when the centre 

 of thefe circles (lands nearer the north than the fouth fide of 

 the tree, and the circles themfelves on the fouth fide are con- 

 fiderably broader than thofe on the north, which is ufually 



the 



