148 Carsten Olsen. 



Anatomy. 



The Leaf. The leaf is dorsiventral as in C. suecica, 

 but differs in having the epidermal cells of about the same size 

 on both surfaces ; also by the cells having strongly thickened 

 outer walls, this latter being caused by the cellulose-mem- 

 brane; the cuticula is quite thin. The palisade-cells are 

 rather thick and short. Apparently there is the same dif- 

 ference between leaf specimens from Greenland and those 

 from more southerly latitudes, as is the case with those of 

 C. suecica. The leaves from Greenland are thicker than 

 those from further South, and the extensiveness of the 

 spongy-tissue is much greater in comparison to the palisade- 

 tissue. 



The following table gives a few measurements of leaves 

 from different latitudes: 



Locality 



Exten- Exten- 

 Thickness siveness of siveness of 

 of leaf Palisade- Spongy- 

 tissue tissue 



Greenland 90 /a 16 , u. 56 ft 



Vancouver Island 60 - 18 - 30 - 



Minnesota 55 - 20 - 26 - 



New Foundland 70 - 16 - 37 - 



Turnavik (Labrador) 50 - 19 - 25 - 



Specimen from the Botanical 



'Garden at Berlin 77 - 27 - 40 - 



On the American specimens the epidermis of both surfaces 

 have strongly undulating sidewalls, while this is much less pro- 

 nounced in those from Greenland (Fig. 11). Stomata are only 

 present on the under surface; the specimens of C. canadensis 



mention diclinous flowers, these must ; consequently be very- 

 rare, if existing at all. 



