Notes. 
291 
stolon of Nymphaea flava , which contain five, four, or as few as three 
bundles each, to those with two bundles in the secondary stolons of 
the same plant and of N. blanda , and also in the stem and floral 
peduncles of Cabomba. Indeed, in the secondary stolons of N. flava 
and N. blanda the two bundles of any pair may in their course fuse 
completely together and become a single bundle comparable to 
a bundle in the stem of Nelumbium nuciferum. 
We see then that in this order a complete series of transitions can 
be traced from typical polystely to the well-known astelic condition. 
D. T. GWYNNE- VAUGHAN. 
The Jodrell Laboratory, 
Royal Gardens, Kew. 
DEMONSTRATION OP ROOT-PRESSURE AND TRANS- 
PIRATION. — I have found that root-pressure may be conveniently 
demonstrated and measured by means of an ordinary Bourdon’s 
pressure-gauge. To give an instance: — a few weeks ago, one of 
these instruments, connected with a branch of a Vine growing in 
the open, gave readings up to a maximum pressure of 10 lbs. to the 
square inch. I am arranging to have an instrument of this kind 
made with a special view to this purpose, provided with an adaptation 
for obtaining a graphic tracing on a revolving drum, and I am 
inclined to think that it may be possible by this means to obtain 
more accurate knowledge than we at present possess on such points 
as the daily period of the root-pressure and the influence upon it of 
variations in the external conditions. 
With regard, now, to transpiration, the recent researches of Dixon 
and Joly 1 , and of Askenasy 2 , seem to make the determination of the 
suction-force of a transpiring plant a point of great importance. 
Boehm 3 succeeded in causing a transpiring branch to raise a column 
of mercury 900 m.m. — that is, the branch exerted a suction-force 
of about 140 m.m. — and that is all the information that we possess at 
present in the way of measurement of the force which is now regarded 
as the efficient cause of the transpiration-current. 
A year ago I attempted to make some measurements of this force 
1 Dixon and Joly: On the Ascent of Sap; Annals of Botany, Vol. viii, 1894; 
Proc. Roy. Soc., Vol. lvii, 1895 ; Phil. Trans. 1895. 
2 Askenasy : Ueber das Saftsteigen ; Verhandl. d. Naturhist.-med. Vereins zu 
Heidelberg, Neue Folge, Bd. v, 1895 and 1896. 
3 Boehm : Ber. d. deut. bot. Ges. 1 893. 
