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habit of the plant, the leaves do not require as much protection 
as the species just referred to. Considering both the protection 
indicated in the vegetative structure, and that which appears in 
its anatomy, Diapensia lapponica occupies, however, a very 
high position with regard to xerophytic adaptation, a position 
which is not surprising when we recall the fact that this species 
is a very old Arctic species, doubtless often a form adapted to 
dry soil. The palisade-tissue should rather be characterized as 
well-developed than as slightly developed, although the indi- 
vidual palisade-cells do not attain any especially great height. 
7.—12.— 1908. 
