Caprifoliaceae. 



163 



The spongy tissue, generally consisting of three layers, 

 is connected with the palisade cells by a layer of collecting 

 cells. 



The leaves from Greenland are, as is generally the case, 

 of a smaller size than those from outside the Arctic zone. 



Fig. 6. Transverse section of triarch root (from Greenland). 



The Root (Fig. 6). The primary root dies quickly and 

 is replaced by the fairly numerous adventitious roots, which 

 sprout from nodes on the rejuvenating and fructificating 

 shoots , and ramify freely in the ground ; this latter 

 generally contains many decaying plant tissues, why 

 mycorrhiza formations might be expected on the roots, but 

 such have not yet been, found. The epidermis of the root 

 has thickened inner walls ; the outer walls however are thin 

 and, together with the root-hairs, decay during the second 



11* 



