474 Miscellaneous. 



gauges at once begau to showdiininished pressure, while sap issued 

 freely from the orifice. In fifteen minutes, one pound of sap having 

 escaped, it was found that both gauges had fallen equal to 19-27 feet 

 of water. Upon closing the hole the gauges rose in ten minutes to 

 their jDrevious level, showing that the rootlets had reabsorbed in 

 that brief period the sap which had escaped from the tree, not- 

 withstanding the enormous pressure already existing. 



A stopcock having been inserted into the hole opposite the lower 

 gauge, it was found that the communication between it and the 

 two gauges was almost instantaneous, which appears to prove that 

 the tree was entirely filled with sap, exerting its pressure in all 

 directions as freely as if standing in a cylindrical vessel more than 

 60 feet in height, as indicated by the lower gauge. The sap-pressure 

 continued to increase until, on the 11th day of May, it represented 

 a column of water 84-77 feet in height, which is believed to be the 

 highest pressure of vegetable sap ever recorded. 



The buds of the birch now began to expand, the pressure of the 

 sap to diminish, and the oscillations of the mercnrj- to become more 

 decided and regular than before. The upper gauge ceased to vary 

 May 14th, remaining stationary at zero. The lower one declined 

 slowly and varied greatly, but did not fall below zero until May 18th. 

 On May 27th it also became stationary at zero. The suction mani- 

 fested by the birch was very little, never exceeding 9 feet of water, 

 and continued only for a few days. 



To determine, if possible, whether any other force than the vital 

 action of the roots was necessary to produce the extraordinary 

 phenomena described, a gauge was attached to the root of a black 

 birch tree, as follows. The tree stood in moist ground at the foot 

 of the south slope of a ravine, in such a situation that the earth 

 around it was shaded by the overhanging bank from the sun ; a 

 root was then followed from the trunk to the distance of 10 feet, 

 where it was carefully cut off 1 foot below the surface, and a piece 

 removed from between the cut and the tree ; the end of the root 

 thus entirely detached from the tree, and lying in a horizontal 

 position at the depth of 1 foot, in the cold damp earth, unreached 

 by the sunshine, and for the most part unaffected by the temperature 

 of the atmosphere, measured about 1 inch in diameter : to this Avas 

 carefully adjusted a mercurial gauge, April 26th. The pressure at 

 once became evident, and rose constantly with very sligHt fluctua- 

 tions, until at noon on the 30th of April it had attained the 

 unequalled height of 85-80 feet of water. This wonderful result 

 showed that the absorbing-power of living birch-rootlets, without 

 the aid of any of the numerous helps imposed upon them by 

 ingenious philosophers, such as exhalation, capillaiity, oscillation, 

 dilatation, contraction, &c., was quite sufficient to account for the 

 most essential of the curious phenomena connected with the circu- 

 lation of sap. Unfortunately, in an attempt to increase the capacity 

 of the gauge, the bark of the root was injured, and tliis most in- 

 teresting experiment terminated. There can be little doubt that 

 future trials, carefully conducted with suitable ajiparatus, will achieve 

 even more marvellous results. 



