84 
projecting; also in the present case cells distinctly devoid of 
tannin occur in the middle of the mesophyll. The epidermis 
of the lower surface contains chlorophyll grains as in grandi- 
flora. Warmine has described in his paper, Exkursionen til 
Skagen i Juli 1896 (see above), the anatomy of the leaf of 
this species. He mentions a rather peculiar fact in regard to 
the stomata. On the leaves of “‘light-plants” (from the Danish 
downs) these organs cease to be functional at an early date, 
so that they occur on older leaves as useless structures, but 
in ‘‘shade-plants” (from woods: Tidsvilde Hegn, and Hornbæk 
Plantage) they are well-developed and function normally. The 
specimens which I have examined and which are from Finland 
and the Färöes come nearest to the Danish wood-forms in this 
respect. The stomata do not occur especially along the veins 
as in Pir. grandiflora. In all other points it resembles Pir. 
grandiflora. 
I have made no examination of the roots. 
Pirola secunda L. (Fig. 3). 
Of this species I have had for examination only spirit- 
material from Disco (Porsild) and from Denmark. Further I 
have investigated herbarium-specimens from Holstensborg in 
Greenland, and Asbirgi in Iceland. 
The structure of the leaf corresponds in the main points 
with that of Pir. grandiflora and of minor. 
The upper and lower epidermis are somewhat thicker than 
in these forms. Stomata occur on both sides, but are fewer 
in number on the upper surface, as is the case in Pir. minor. 
On the latter surface the stomata are especially confined to the 
area near the veins of the leaves. Both the upper and lower 
epidermis contain chlorophyll grains. Hydathodes occur, but 
hairs are absent. 
The cells of the mesophyll are of the same form as those 
of the mesophyll in the two above-mentioned species. No cells 
