Dixon — Vitality and IVansmission of Water through Plants. 23 



lateral shoots, aud as similar to one another as possible,' are passed through 

 tuhulures {a and h) in the bottom of a metal cistern, about 65 cms. deep. 

 The upper ends of the branches projected above, and the lower ends below, 

 tlie cistern. The joints round the lower ends 

 were rendered water-tight by binding on a 

 rubber tube overlapping the tubiilures and the 

 projecting ends of the branches. The cistern 

 may now^ be filled with water which, if kept 

 in motion, will secure that botli branches are 

 aliuost at the same temperature, and so differ- 

 ences in viscosity in the water passing through 

 the branches will not arise. 



In order to avoid irregularities in trans- 

 mission, much care is needed in the prepara- 

 tion of the branches. After selection of the 

 branches, the upper leafy part is cut away, 

 and the cut surface of the lower part still 

 attached to the tree is moistened by a jet ot 

 water. This part is now cut oli under water, 

 and while still submerged is removed to tlie 

 laboratory. Fresh surfaces are now prepared 

 at each end, and smoothed off by a razor, 

 under a stream of distilled water. A widu 

 glass tube about 20 cms. long is attached to the 

 upper end of each branch. This is kepi full 

 of distilled water, which acts as the supply and 

 head, driving the water downwards through 

 the branches. If it is desired to apply picric 

 acid or some other poison as a killing agent, 

 the simple glass tube is replaced in each case 

 by one which is provided with a side tubulure, 

 bent in a J form, and with two stop-cocks 

 placed as shown in fig. 1. 



The rate of transmission from above down- 

 wards is first observed for the two branches by 

 weighing the amount of water transmitted in 

 a given time (say, 10 min.J. It is evident if 

 vital actions are at work tending to raise the water in the branches, the rate 



' 1 used Syr'xnga viili/iiris, as similar and straight brunches of this shrub are readily ohlaiiicd. 



e2 



