122 



walls of the guard-cells and of the neighbouring cells is cuti- 

 cularized. The palisade-cells occur in several layers and are 

 about 50 jx in length. In regard to the palisade-tissue the 

 Subarctic and the Arctic specimens do not appear to be in 

 any way inferior to the Danish specimens (of the typical species). 



Fig. 33. Vaccinium Vitis-idcea. 

 Transverse section of stem, x 180. (Greenland.) (Phot.) 



In shade-forms (which, as is well-known, always accompany light- 

 forms). Subarctic specimens of which, however, I have not had 

 for investigation, the elements of the leaf are naturally reduced 

 in size (especially the palisade-tissue). The spongy parenchyma 

 is not much branched and has very large intercellular spaces of 



