Stomata in Halophytes. 487 
the plant : this was done in order to avoid as far as possible the shrinkage 
which has been demonstrated to take place in many leaves even before 
withering becomes perceptible. 1 
For the very small boat-shaped leaves of Suaada, and for the jointed 
swollen stems of Salicornia , I have used methods which were originally 
suggested to me by Mr. T. G. Hill. In the case of Suaeda ten or twelve 
leaves were cut off quickly from the stem and placed side by side on paper 
ruled in millimetre squares. The outline of the whole was then traced with 
a sharp pencil, and twice the area marked out was taken as a rough approxi- 
mation to the transpiring surface of the leaves. This was repeated until 
all the leaves from the experimental shoot had been measured. The surface 
area of the stem, if this was herbaceous, was also included in the total 
transpiring surface thus estimated. 
In the case of Salicornia , a number of measurements of the diameter 
were made by means of a micrometer screw reading to x ^o mm. ; usually 
one measurement was made near the upper part of each internode. The 
Fig. 1. Single leaf Fig. 2. Outline obtained by Fig. 3. A shoot 01 Salicornia annua 
of Suaeda maritima. placing leaves of Suaeda side with uneven internodes, 
by side, and tracing area covered 
on squared paper. 
height of the shoot was measured, and the transpiring surface was then 
estimated as [average diameter x 7 r x height]. Now the diameter varied 
considerably amongst the specimens which were examined. Some possessed 
stems with a nearly even cylindrical surface, and tapering only slightly at 
the tip ; others showed an uneven surface, each segment being wider above 
than below, and more or less laterally compressed in the upper part : the 
stem often tapered considerably at the tip. As far as possible, even, bluntly 
ending stems were chosen for experiment, but in the specimens with taper- 
ing internodes a very fair average diameter can be found by measuring just 
below the broadest region, taking if necessary the mean of the narrower 
and wider dimensions at that level. For example, in a small plant with 
markedly tapering internodes the following figures were obtained in 
measuring the internode next above the hypocotyl : — 
1 Thoday, D. (’ 09 ) : Experimental Researches on Vegetable Assimilation and Respiration, V. 
Proc. Roy. Soc., B., vol. lxxxii, 1909. 
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