But coloured 

 infusions will 

 pass through 

 tke cellular 

 Substance. 



20 ON TtiE ALBURNUM OF TREES* 



lular substance of an oak, it appears possible at least* thai 

 Celoured infu- tne whole of the sap may ascend through it. Coloured in- 

 sions not pas- f u9 ions do not, 1 think, in any degree* pass through the bark 



sing, no proof „ . . . - . * , J?« . . , 



that sap does °* tre ^Sj yet it is evident, that the sap passes readily through 



not. it; and therefore should it be proved, that such infusions do 



not penetrate the cellular substance of the alburnum* the 



evidence which this circumstance would afford would be very 



defective. 



Among other experiments which I made to ascertain whe- 

 ther the cellu]ar substance of the alburnum would imbibe 

 coloured infusions, I took off branches of two years old with 

 the annual shoots and leaves attached to them, in the sum- 

 mer, from trees of different species ; and I effectually closed 

 the albumous tubes with a composition formed of calcined 

 oyster shells ahd cheese*, and this was covered with a mix- 

 ture of bees wax and turpentine, so as effectually to exclude 

 all moisture. A part of the bark was taken off each branch, 

 in a circle round it, a few lines distant from its lower end, 

 where the tubes had been closed; and each branch was then 

 placed in a decoction of logwood, in a vessel deep enough to 

 cover the decorticated spaces. At the end of twenty hours, 

 or somewhat longer periods, these branches were examined, 

 and the coloured infusion was found to have insinuated itself 

 between the alburnous tubes, in many instances apparently 

 through the cellular substance. This was most obvious in 

 the walnut tree, the young wood of which is very white. 

 The principal object I had in view in making this experi- 

 ment was, to-detect the passages through which I conceived 

 the sap to pass from the bark into the albumumf. 



From the preceding circumstances, I am disposed tp in- 

 the cellular ^* er » tnat tne sa P secretes through the cellular substance of 

 the alburnum; and through this I conceive that it must as- 

 cend, when the tubes were intersected in the preceding ex- 

 periments, and in those seasons of the year when the albur- 

 nous tubes are empty, though the sap must be rising with 

 great rapidity: and I shall endeavour to show, that the p re- 

 Effectual ce- # I have found this composition, and this only, to be capable of in- 

 nient to stop stantaneously stopping the effusion of sap from the vine, or other tree in 

 the bleeding of lhe bleeding sea son. 



f Phil. Trans, 1807, p. 107 ; or Journal, XIX, p. 24$. 



sence 



The sap se- 



substance of 

 (he alburnum, 



