66 
Margaret W. Rea 
This agreed with Sierp’s similar observations in Mirahilis jalapa, 
Nigella damascena and Pisum sativum. The higher the leaf the 
smaller its cells.” The results obtained in 1917 when examining the 
leaves of the Benevenagh plant were thus confirmed. These factors 
would probably counterbalance the effect of any stomatal increase 
on the upper leaves of the shoots. Conversely the shade plant had 
more rotund and thinner leaves than the normal shoot. The part 
that hydathodes play in connection with water-loss in the leaves 
of Campanula rotundifolia examined, will be considered in the next 
section. 
HYDATHODES. 
While the leaves of the various plants were being examined for 
stomatal distribution, it was thought that the number of hydathodes 
which occurred on their upper surfaces might show some relation 
to their position on the leaf, to the position of the leaf on the shoot 
and to the environment of the plant. 
The position and number of the hydathode groups on each 
margin of the upper surfaces were noted as shown in fig. 1. The 
total number of pores per leaf was ascertained and the results are 
given in the Tables V to VII, pp. 68 and 69) and are shown in the 
graph (see fig. 6, p. 67). 
The hydathodes were developed on the lower leaves on slight 
marginal projections at the club-shaped terminations of the prin¬ 
cipal veins and the midrib. Usually there were three groups of 
hydathode pores on each margin, occasionally there were four or 
even five, nearly opposite each other, besides the apical one (see 
1). 
The number of pores in each group varied, being most numerous 
in the apical group with one or two exceptions; and decreasing 
from apex to base of each leaf. The total number of pores per leaf 
shows a decrease from base to apex of each shoot. In a few instances 
the basal hydathodic organs had only one or two pores. The inter¬ 
mediate type of leaf had fewer marginal groups and only an apical 
one was present on the upper linear leaves. The individual pores 
were observed to be larger and clearer on the shade plant than on 
the normal or the sun shoot. The three leaves had the following 
number of pores present; on the lower leaf 32 pores; on the middle 
leaf 20 pores; and on the upper leaf 7 pores. 
On the “whole” shoot the marginal groups were irregular in 
distribution, two being the highest number observed on either 
