109 



in all the cells, and is easily discernable in fresh material, but 



in spirit material it is seen only in the walls, which are found 



to be saturated with it, 



and some more than 



others (cf. Schulz). It is 



possible that the tannin 



is not distributed quite 



evenly. 



Specimens from the 

 bog at Farum (February, 

 1907) demonstrated very 

 perfectly the Kraus 

 winter-condition. The 

 palisade-cells which are 

 devoid of chlorophyll 

 gave an exceptionally 

 good reaction for tannin 

 (cf. Warming, Beobach- 

 tungen über Pflanzen mit 

 überwint. Laubblälter. 

 Bot.Centralblatt, Bd. 16, 

 p. 350). 



Below the central 

 vascular bundle a tissue 

 occurs consisting of 

 very thin-walled cells 

 (Fig. 23, 6), sometimes 

 traversed by thick-walled 

 cells which run from 



the ring of bast to the epidermis, a kind of aqueous-tissue. 

 A similar tissue is also met with in Ledum palvstre. Stereom 

 is developed thickly around the vascular bundles. In regard to 

 the structure of the leaves, excepting the difference already 

 mentioned with reference to the development of hairs, which 



Fig. 24. Andromeda polifolia. 



Transverse section of stem. X 180. (Tiningnertok.) 

 (Phot.) 



