STATE OF THE SAP IN WINTER, i J Q$$ 



cannot believe that the matter which compofed thefe buds and 

 leaves could have been wholly prepared by the feeble vegeta- 

 tion and fcanty foliage of the preceding year. 



But whether the fubftance which is found in the alburnum it is ftrongly 

 of winter-felled trees, and which difappears in part in the P r ? b a b ' e that 



r ' J i r . r • -]• thlS mattcr co »« 



ipnngand early part of the fummer, be generated in one or po f es t h e leaf, 

 in feveral preceding years, there feem to be ftrong grounds 

 -of probability, that this fubftance enters into the composition 

 of the leaf: for we have abundant reafon to believe that this 

 organ is the principal agent of aflimilation; and fcarcely any 

 thing can be more contrary to every conclution we fhould 

 draw from analogical reafoning and comparifon of the vegetable 

 with the animal economy, or in itfelf more improbable, than 

 that the leaf, or any other organ, fliould (ingly prepare and 

 affimilate immediately from the crude aqueous fap, that matter 

 which compofes itfelf. 



It has been contended * that the buds themfelves contain jt is not likely 

 the nutriment neceffary for the minute unfolding leaves : but *** the y , are , 



J ° fupported by the 



trees poflfefs a power to reproduce their buds, and the matter crude fap. 

 neceffary to form thefe buds muft evidently be derived from 

 fome other fource: nor does it appear probable that the young 

 leaves very foon enter on this office: for the experiments of 

 Ingenhouz prove that their action on the air which furrounds 

 them is very efTentially different from that of full grown 

 leaves. It is true that buds in many inftances will vegetate, 

 and produce trees, when a very fmall portion only of albur- 

 num remains attached to them; but the firft efforts of vege- 

 tation in fuch buds are much more feeble than iii others to 

 which a larger quantity of alburnum is attached, and therefore 

 we have, in this cafe, no grounds to fuppofe that the leaves 

 derive their firft nutriment from the crude fap. 



It is alfo generally admitted, from the experiments of Seeds are thus 

 Bonnet and Du Hamel, which I have repeated with the fame "lifted not 

 retult, that in the cotyledons of the feed is depofited a quantity but from matter 

 qf nutriment for the bud, which every {eed contains; and dc P ofited intlve 

 though no veflels can be traced + which lead immediately 

 from the cotyledons to the bud or plumula, it is not difficult to 

 point out a more circuitous paffage, which is perfectly fimilac 

 to that through which I conceive the fap to be carried from the 



f Thomfcn's Chemiftry. t Hedvrig. 



leaves 



