374 



Fr. J. Mathiesen. 



layered cork (cf. Fig. 2). The walls of the primary cortex 

 attain a rather considerable thickness; this is especially the 

 case as regards the endodermis; both in this and in the 



^^^^^SdbtetftC 



Fig. 3. Veronica fruticans. 

 Transverse section of the stem (about '■^""/i). (Greenland.) 



other layers, radial walls are formed during the secondary 

 growth of the root. 



In the wood of the 2-year-old root illustrated in Fig. 2, 

 an annual ring is formed outside the central part which was 

 developed during the first year; the limit between them is 



