Caprifoliaceae. 



161 



material from Greenland, where the walls also were thicker. 

 The stomata, which are only found on the lower surface, 

 are somewhat projecting, oval, and of the usual structure 

 (Fig. 3). 



The following table shows the average number of std- 



Fig. 4. Transverse section of leaf (from Denmark). 



mata on ^io mm- of 6 leaves from Denmark compared 



with 6 from Greenland : 



Leaf .... 1 2 3 4 5 6 pr. mm 2 



Danish . . 49 39 51 45 39 55 463 



Arctic ... 40 44 47 40 48 45 440 



On 1 mm- the average was about 450 stomata. 



The undulation of the perpendicular cell walls of the 

 epidermis is still more pronounced on the lower surface of 

 the leaf than on the upper surface. Besides, the material 

 from Greenland also showed a thickening, and larger undu- 



XXXVII. 11 





