1905] DARBISHIRE—APPARATUS FOR TRANSPIRATION STREAM 357 
portions of the plant entirely, but rather to keep them connected 
by some continuous bit of apparatus, so that, although the plant 
be cut in two, the shoot suction may still act on the root or the root 
pressure on the shoot. I use for this purpose a simple bit of glass 
apparatus, which I have called a pinometer. It will be necessary 
first to describe the apparatus; secondly, the way it is set up; and 
finally, to refer to a few of the experiments and the results 
obtained. 
The pinometer consists of a straight bit of glass tubing (jig. 1, b-d), 
to which is obliquely attached by annealing on one side another short 
bit of glass tubing (c-/). On the opposite side a U-tube with an 
oblique connection is annealed on (a-e.) We have therefore four 
Openings to this part of the apparatus (a, 6, c, d). The bore of the 
glass tubing used for the pinometer depends entirely on the thick- 
ness of the stem of the plant used. The diameter of the glass tubes 
should about equal the diameter of the latter. A very convenient 
plant to use for demonstration purposes is a healthy fuchsia plant, 
not exceeding two feet in height. 
The experiment should not be set up till all the various parts 
and tools are quite ready. The glass tubing should be cleaned to 
Temove any greasiness, which is often the cause of introducing minute 
air bubbles into the system of tubes. The air should also be care- 
fully removed from the rubber tubing. The more quickly every- 
thing is set up, the more nearly will the results obtained show what 
Was going on in the plant at the time the experiment was made. 
When everything is ready, the plant in its flowerpot is put into 
a bucket of water, so that it is immersed to a few inches above the 
point at which it is to be cut across. The leaves should not be mois- 
tened more than is absoluely necessary. The stem of the plant is 
Now cut across under water in such a way that there is about one 
inch of stem, above and below the cut, devoid of buds or branches. 
Tf the stem has already a complete wood cylinder, the cortex may 
be removed with a sharp knife for about half an inch above the cut 
on the shoot, and below on the root. 
The lower end of the shoot, without removal from the water, 
is fixed by rubber tubing to the opening a, jig. I, and the portion a-e 
of the pinometer remains full of water, even when removed from the 
