123 



about the same size as those in the palisade-tissue. No aqueous 

 tissue occurs, nor is the stereom especially well-developed. 

 In the material I had for investigation no difference could be 

 observed between the Danish, the Subarctic and the Arctic 

 specimens. But here, as was the case with regard to the other 

 species, the material was too scanty to be useful for the 

 investigations in question. The specimens from Furca Pass, 

 Switzerland (Aug. 1904; H. E. P.), did not shew any differences 

 of importance. 



The stem. According to Tedin (1892, p. 74) the primary 

 cortex consists partly of transparent, thin-walled cells containing 

 water and partly of thick -walled cells which contain chlorophyll 

 and occur partly in trabeculae and partly in groups (cf. e. g. 

 Ledum]. It persists for about three years. The secondary 

 cortex, according to Segerstedt, consists of an ordinary cork- 

 tissue. 



The spring wood is differentiated from that of the summer 

 (or autumn); but the limits of the annual rings are not always 

 sharply defined. According to Simon (1902) the cause of the 

 distinctness of the annual rings in Vac. Vitis-idœa., and of the 

 differentiation of the wood of the different seasons as mentioned 

 above, will be found in the fact that evergreen forms require 

 more stereom, while the deciduous forms need relatively more 

 "Speichergewebe ;"' but this is scarcely to be regarded as a 

 universal rule (cf. Ledum, Rhododendron., etc.). 



The roots I have had for examination from Hovmose in 

 Gadevang at Frederiksborg shewed both endotrophic and ecto- 

 trophic mycorhiza. 



Taccinium uliginosum L. (with f. microphylliim Lge.) 

 (Figs. 34—37.) 



BöRGESEN, 1895, pp. 236 — 237. Segerstedt, p. 25. Ambronn, 

 1890, p. 71. 0. G. Petersen, 1901, p. 81. Hesselman, 1900, p. 27. 

 Maury, 1887, p. 105. 



