358 BOTANICAL GAZETTE [MAY 
water, and can be temporarily held by a clamp (7) on a retort stand." 
Next some rubber tubing is slipped over the upper end of the root 
stump. This bit of tubing also fills with water and the whole 
flowerpot can now be removed. The end 6 of the pinometer is now 
quickly fixed to the rubber tubing over the stump. A gauge is 
securely attached to c, and water is poured into d from a small 
reservoir (jig. 3, r) till the whole system of tubes is full of water. 
Mercury is then poured into the outer limb of the gauge, and this 
causes water to pour out at d, to which some pressure tubing has 
been firmly fixed. When there is enough mercury in the gauge to 
give the columns sufficient play to rise and fall, the opening at d 
should be closed by a pinch-cock and the experiment is set up. Retort 
stands and clamps are used for keeping the various parts in position, 
and a millimeter scale (k) can be attached to one or both limbs of 
the gauge. | 
Should air make its appearance, it will collect under d, if it comes 
from any part of the plant except the lower end of the shoot. It 
can be removed from d by opening the pinch-cock and allowing water 
to run in from the reservoir. Should it accumulate under a, the 
shoot must be removed from the rubber tubing attaching it to the 
glass, and water allowed to enter the pinometer at d rather slowly. 
It will then be running out slowly at a, and the shoot is again fixed, 
the current of water preventing any air getting in. 
In any case the removal of air means the opening of the pinch- 
cock at d, and this causes the mercury to go back to its starting point. 
This can be obviated by inserting a stop-cock between the oblique 
bit j-c (fig. 1) and the gauge. I do not however consider this necessary 
for the apparatus, which as described here is intended chiefly for 
qualitative and not quantitative observations. 
The results obtained with the pinometer depend very much on 
the point at which we fix it in the plant. I will refer therefore to 4 
few actual experiments, which I hope will show the value, however 
small, of the simple bit of apparatus just described. 
In the first experiment to be described, a pinometer was fixed to 
t For fixing the plant to the glass tube it is best, if possible, to employ some kind 
of pressure tubing. ‘The latter can be made secure by tying with string or by employ- 
ing some kind of clamp. The use of wire is to be deprecated. 
irate oc 
