460 The Botanical Gazette. [October, 
lected on the shore of these islands where heavy fogs prevail 
during the summer we do not get a complete illustration of 
the anatomy of the arctic plants. The climatic conditions 
vary greatly in the polar regions, and there are certainly 
many places, where the summer has sunny days with clear 
sky, at least during the months of June and July. The paper 
is nevertheless very interesting and we record some of the 
most important results. Oxyria digyna, Saxifraga oppositi- 
folia, Salix reticulata, Silene acaulis, Cerastium alpinum, 
Potentilla nivea and Poa pratensis are described anatomically, 
and a few other species are briefly discussed. The anatom- 
ical examination comprises the leaf, the stem, the in- 
florescences and the root, and the accompanying plates contain 
several good figures showing the habit of some of these species 
and their anatomical structure. As compared with their 
alpine representatives the following modifications are observ- 
able as characteristic of arctic species: ‘ 
1. The lignified elements are reduced in number; their cell- 
walls are less thick and the lumen of the vessels much nar- 
rower than in the alpine plants. 
- The leaves are thicker but less differentiated; the 
palisade tissue is less pronounced; the intercellular spaces are 
more developed 
3. The epidermis of the stem and leaves is less coherent 
and the cuticle less thick. 
4. The cells of the various tissues of the stem, the leaves 
and the root show a tendency to a roundish outline; some 
of the ceils often develop like trabecule, and these separate 
large intercellular spaces. ; 
The author believes that the causes of these anatomical 
modifications are especially the atmospheric humidity and oe 
character of the light. The most important factor is, ° 
course, the light of the midnight-sun which is continuous In 
the summer months, but not so intense as the light in the 
Alps. The humidity of the soil and the temperature do not 
Seem to cause any modifications of importance, at least not 
in the plants examined.—THEO. Hot. 
