Comaceæ. 



149 



from Greenland having 160 of these pr. square^mm, while 

 specimens from Canada had only c. 140 pr. sq. mm. 



The Stem. The stem 

 is very much like that of 

 C. suecica, the transverse 

 section being however 

 somewhat different. As 

 Fig. 12 shows, the stem 

 of C. suecica seen in trans- 

 verse section is more bar- 

 rel-shaped, and the groove 

 not very deep, while that 

 of C. canadensis is con- 

 siderably deeper, making the stem "four-winged"; besides 

 this, the circumference of the medulla of C. canadensis is 

 quadrangular, while that of C. suecica is round. In C. cana- 



Fig. 12. 



Transverse sections of stems. A, Cornus cana- 

 densis from Vancouver Island ; B, Cornus 

 suecica (Greenland); C, Cornus canadensis from 

 Greenland; A, B and C about u /,. 



O o0 °n 

 â°Oo°o°<& 







Fig. 13. 



Transverse section of the winged part of the stem. A, Cornus canadensis from Vancouver 

 Island ; B, Cornus suecica from Greenland ; C, Cornus canadensis (Greenland) ; A. B and 



C about "«/,. 



densis the distal part of the wings of the stem consists of collen- 

 chyma while such is practically missing at this place in C. 

 suecica (Fig. 13). 



The sclerenchyma in the bark of C. canadensis is often 

 greatly developed in vigorous specimens, while it is about 



