268 



Eue Warming. 



This is evidently a structure which is due to the faint 

 light and the damp surroundings, and which contrasts 

 strongly with the leaf-structure of the Alpine plants (Wagner 

 and Börgesen). 



In contradistinction to the Arctic Carijophyllaceæ we may 

 refer e. g. to Silène Otites from dunes near Montpellier, 

 which has palisade-tissue on both sides (Warming, Halofyt- 

 studier, 1897, p. 203) and Silène nicæensis from Cadix (ibid., 



Fig. 23. Arenaria ciliata. 

 (From N. E. Greenland; 12. 7. 1908; A. Lundager.) 



A, Transverse section of leaf; two cells with crystals of calcium oxalate. 



B, A leaf; the dots indicate cells with crystals. C, D, Transverse section 



of leaf, showing the crystals. (E. W.) 



p. 198), together with Honckenya from Denmark which, when 

 growing on sand strongly exposed to the sunlight, can have 

 several layers of palisades on both sides (Warming, 1891, 

 Fig. 12). 



Many records as regards anatomical differences in plants 

 from different countries, and variations in the same species 

 from different habitats, and in different countries, are found 

 in Heinricher, Börgesen, Warming and others. It is evident 

 that the local conditions prevailing in the habitats, are in 

 epharmony with the differences in the individuals. As an 

 example of this, the reader is referred e. g. to Joh. Schmidt's 



