BOTANY OF THE CEYLON PATANAS, 449 
The two plants, Lobelia nicotianefolia and Osyris arborea, of 
which leaves from both patanas have been investigated, bear out 
the first statement. The stomata in both cases were found more 
numerous per unit area on the dry patana plants. One explan- 
ation forthcoming is that the leaves of a given species are apt 
to be smaller in area in the light than in the shade, and taking 
the number of stomata per each leaf as equal, then the sun-leaves 
will have more to the square millimetre. 
As regards the position of the stomata with respect to the 
general leaf-surface :— 
Out of 42 w.ps., 14 with stomata level, 21 raised, and 7 sunk. 
” 40 d.ps., 26 ” ” 6 ” 8 ” 
Thus sunken stomata are about as common in one region as in 
the other, showing again that xerophytic characters are about as 
marked amongst one group as the other. 
The larger number of raised stomata amongst the w.ps. is 
probably due to the greater frequency of a hairy leaf-surface. 
(8) Mesophyll. 
Average thickness for w.p......... 234 p. 
» ” » G.peee sce eee 225 p. 
The difference here is too slight to be taken into account. 
Yet the dissimilarity might have been expected to be the reverse 
of what it is, since sun-leaves are thicker than shade-leaves. 
Proportion of spongy tissue to palisade, w.p. 1: 1'5, d.p. 1:6. 
No appreciable disagreement, both sets of leaves calculating 
out to about the same ratio, viz. :—the spongy tissue being about 
one and a half times as deep as the palisade. 
There is a greater inclination amongst the d.ps. to have a two- 
layered palisade. 
d.p., 82 p.c. have a two-layered palisade. 
W-~p., 21 p-c. ” ” ” 
Ratio of the length of the palisade-cell to its breadth. 
Average for W.p........-.- 4°3. 
” ” d. ) 55. 
Thus the palisade character is more pronounced amongst the 
d.ps., as might be expected. This still remains the case if the 
erect and semi-erect leaves are omitted from both groups; the 
ratio then is for w.p. 4°5, for d.p. 5°8. 
