LICHENS. 151 
loped it forms tufts nearly a foot in length. It is 
quite a miniature larch tree with root, stem, and 
most intricate branches and twigs. Its colour is 
pale sea-green ; and a central white thread or 
pith runs through the main stem, and lateral 
branches, on which, when cracked with age,the seg- 
ments of cellular tissue are strung like beads on a 
necklace. A kind of farinaceous meal is plenti- 
fully sprinkled on the ultimate branches. Alto- 
gether it is one of the most beautiful and interest- 
ing of our native lichens. A reddish variety grows 
in such quantities on trees of Conyza arborea form- 
ing the alley near Napoleon Buonaparte’s resi- 
dence in St. Helena, that this hanging vegetation 
is the first thing that attracts the eye of the visitor. 
But it is not to animals alone that lichens 
- furnish a supply of food. Man 
himself is frequently directly 
indebted to them for subsist- 
ence. There are few, I pre- 
sume, who are not acquainted 
with some particulars regard- 
ing the history and uses of that 
remarkable lichen, sold in che- 
mists’ shops under the name 
of Cetraria Islandica, or Ice- 
Fig, 13. Cerarta Istannica- land moss (Fig. 13). Although 
in this country it is only used medicinally, as a 
