572 



Proceedings of Learned Societies. 



[Jan. \f 



■were fiiflicicnt to prcfervc life. In lliis 

 poiiiion I coiKcivinl, thai it'tlicir leaves 

 and Uenis coiitaiucii any uiicniployefi 

 Irue Cap, it could not readily (ind its vvay 

 to the tuberous roots, its paflage being 

 obihutted by tlie rupture of the veffels 

 and by gravitation ; and 1 had f<jon the 

 plcallue to fee that, inllcad of return- 

 ing down the j)nneipal item into the 

 ground, it remained, and formed fniall 

 tubers at the bafe of the leaves of the 

 depending branches." 



Tlic preceding fafis fecm to prove, 

 that the lluid from which tiie tuberous 

 root of tJie potatoe, when growing be- 

 neath the foil, derives its component 

 matter, exifts previoully eitiicr in the 

 Hems or leaves: and that it fubfequently 

 defccnds into the eartli ; anil as I lie coi- 

 tical veU'els, tluring every period of the 

 growth of the tuber, are tilled with the 

 true fap of the plant, and as thefc vef- 

 fels extend into the runners which carry 

 nutriment to the tuber, and in other in- 

 ftanccs evidently convey the true fap 

 downwards, there appears httle reafon 

 to doubt that through thefc velfels the 

 tuber is naturally fed. 



To afcertaiu whether the tubers would 

 continue to be fed v\lien the palfagc of 

 the true fap down the cortical veiVols 

 was interrupted, Wr. Knight removed a 

 certain portion of the bark : for fome 

 time the plants continued in iiealth, and 

 during that period tlie tubers continued 

 to grow, deriving their nutriinrnt, pro- 

 bably, from the leaves, by an inverted 

 action of the ulburnous vellels. The 

 tubers, however, did not attain their 

 natural fizc. 



Mr. Knight has proved, witli ampu- 

 tated branches of dill'ercnt fpccics of 

 trees, that the water which their leaves 

 abforb when immeried in that (laid will 

 be carried downvvards by the albiini'im, 

 and conveyed into a portion of bark be- 

 low the decorticated i'pace; and that the 

 infulated bark will be prel'erved alive and 

 jnoift during fevcial days : and hence he 

 infers, that if the nioilture ab'orbed by 

 a leaf can be thus tiansferied, it appears 

 extremely probable that the true i'ap 

 will pafs through the fame channel. 

 This power in the alburnum to carry 

 fluids in different dirttiions, probably 

 anfwers very important purpofes in hot 

 climates, where the dews are .ibuiiil uit, 

 and the foi^ very dry ; for the moillure 

 ■which the dews afford may thus be con- 

 veyed to the extremities of the roots ; 

 and Hales has proved that the leaves 

 abforb laoft when placed in moift air, 



and that the fap defccnds cither through 

 the bark or alburnum during the night. 



Mr. Kiiisiht notices in this paper, that 

 during the circulation of the fap ilirougU 

 the leaves, a tranfparcnt fluid is emitted 

 in the night fron) pores litualed on their 

 edges; and on cvaprwatiiig this liquid, 

 obtained from very luxuriant plants of 

 the vine, he found a very large rcfidue, 

 fnnilar in external apyieaiance to carbo- 

 nate of lime. Another curious obferva- 

 tion is, that the roots of trees, though 

 of much lefs diameter than their trunks 

 and blanches, probably contain much 

 more alburnum and birrk, becaufe they 

 arc whollv without heartwood, and ex- 

 tend to a much greater lengtii than tlie 

 branches: hence he fufpects, that when 

 fir-trees are felled, their roots contain 

 as nnieh relinous matter, in a lluid fiate, 

 as their trunks and branches, , though 

 not fo much as is contained, in 'U' con- 

 crete ftate, in the heart-wood of tho fe. 



TIIK BOARD OF AGRICULTURE. 

 r'f^III.S Society have offered the foUow- 

 X. ing fiibjects f jr premiums for llie 

 prefent year : 



No. I. Cottage. 



To tlic pnrfon who (lull build, and defcrilie 

 to the Bojrd, the clicapeft cottjge ; lit-ing at 

 the fame time durable and comlortable, with 

 not lefs than two rooms above, and the fame 

 numlier below— the gold medal. 



A plan, elevation, and account of the ma- 

 terials and expence, verified by certificates, 

 to he produced on or belbre the firft Tuefday 

 in May, 1U07. 



No. II. Cottage. 



To the perfon who ihall produce to the 

 Board, the model of the beft and chtxipeft cot- 

 tage, on a fcale of one inch to a tout, with 

 eftiniates of the expence of creeling it — from 

 five to ten guineas, according to merit. 



To be produced to the Board on or before 

 the firll Tuefday in December, 1806. 

 A'e. ///. C^Hjg.s. 



To the perfon who fliall build on his ellate 

 the mod cottages (proportioned to the rental 

 of It) for labouring families, and alftgn to 

 each land fufficient for a garden, not lefs thaa 

 one tliiid of an acre— tlic gold medal. 



Accour.ts of the expences of building- 

 land affigned— culture, if any — and ftate of 

 the families, with the rent paid, verified by 

 certificates, to lie produced to the Board on or 

 before the third Tuefday in April, 18ur. 

 No. IV. Cyzvs for Ccrtagers. 



Doubts having been c xprefied by fome per- 

 fons, concerning the expediency of cottageri 

 keeping cows, except on rich foils, the Board 

 will give to the perfon who fiiall give the 

 moft fatisfaftory account, verified by experi- 

 ments, of the heft means of fupportirg cows 



