VOL. VI.] PHILOSOPHICAL TRANSACTIONS. fl/f 



one of the branches of this plant, as hard as might be, and not break the skin : 

 there followed no greater swelling, that I could discern, on the one side of the 

 silk more than on the other; although in often repeating the experiment, some 

 silks were left hours and days unloosed, and yet the dimple which the thread had 

 made in the yielding branches, had a little raised the immediate sides, but both 

 alike : the plant in like manner would bleed ver)' freely both above and under 

 the tie. This was also, I thought, very remarkable, amongst other things, in 

 this experiment, that in drawing the rasor round about the branch just above 

 or below the tie, the milky juice would suddenly spring out of infinite small 

 holes, besides the orifice, for more than half an inch above and below the tie : 

 which seems to argue, that though there was no juice intercepted in appearance 

 from any turgescence, (as in the process upon the members of a sanguineous 

 animal) yet the veins were so over-thronged and full, that a large orifice was 

 not sufficient to discharge the sudden impetus and pressure of a someways 

 straightened juice. 



That I might satisfy myself about some of my doubts, I have been most con-* 

 cemed, according to former thoughts and inclinations, in examining the truth 

 of these queries, viz. Whether saps are not to be found at all seasons of the 

 year in a much like consistence and quantity in the respective parts of a vegeta- 

 ble; and what communication one part of a plant may have with another in re- 

 lation to the ascent and descent of sap ? 



Now, because sap is then said to ascend from the root, when it is found to 

 move in tapping; I lopped off certain branches of a sycamore, the morning be- 

 times of a hard frost (Feb. 21) before they would bleed, or show any sign of 

 moisture. This I did to vary the efficient, not willing to wait the change of 

 the weather, and the sun's heat ; but brought them within the air of the fire: 

 And by and by, as I expected, they bled apace, without being sensibly the 

 warmer. 



The experiment repeated affi^rded me several phaenomena, which follow; and 

 almost proved an universal way of bleeding all sorts of trees, even those which 

 of themselves would not show any signs of moisture. ^ 



Poles of maple, sycamore and walnut, cut down in open weather, and brought 

 within the warmth of the fire, did bleed in an instant. Also willow, hazel, 

 cherry, woodbine, blathernut, vine, elder, barbery, apple-tree, ivy, &c. 

 Whicking and egg-berry tree (i. e. padus Theophrasti) tried in the same manner 

 in Craven. — Briar and raspberry-rods were more obstinate. Ash utterly refused, 

 even heated hot. — Branches, that is, poles with their tops entire and uncut, 

 bleed also when brought to the fire side ; but seem not so freely to drink up 

 their sap again when inverted, as when made poles. — The same willow-poles, 



VOL. I. 4 D 



