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. Scrurz). It is 
possible that the tannin 
is not distributed quite 
evenly. 
Specimens from the 
bog at Farum (February, 
1907) demonstrated very 
perfectly the Kaars 
winter-condition. The 
palisade-cells which are 
devoid of chlorophyll 
gave an exceptionally 
good reaction for tannin 
(cf. Warmine, Beobach- 
tungen über Pflanzen mit 
überwint. Laubblätter. 
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 
TRE 
a 
A + 
8 eg 
ASF 
Fig. 24. Andromeda polifolia. 
Transverse section of stem. >< 180. (Tiningnertok.) 
(Phot.) 
the ring of bast to the epidermis, a kind of aqueous-tissue. 
A similar tissue is also met with in Ledum palustre. 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 
