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would be no food. In waste districts of Africa and Western Asia 
the edible lichen, Zecanora esculenta, or ‘“manna of the desert,’ is 
of great value as food for man and beast. Several near relations 
of this plant—that is to say, several species of Lecanora, are to be 
found in our own neighbourhood, but they are not at all like their 
more useful brother. The desert manna is said to be never attached 
to anything, so that it must live almost entirely upon air. The dyer 
uses several lichen-products, such as litmus, archil, cudbear. They are 
not exactly obtained from the plants but rather prepared from them 
by the action of certain chemicals. ‘The litmus referred to is the 
substance from which are obtained the blue solution and paper 
which the chemist uses as a test. Beginners in chemistry will 
remember that acid solutions change the blue colour to red. The 
use of chemical processes in obtaining the dyes seems to favour 
the idea of chemical tests as a means of distinguishing one species 
from another. In Lapland, the “ Iceland Moss’’—pray let it be called 
Iceland dichen—and the ‘‘ Reindeer Moss”’ (lichen), are simply in- 
valuable, the latter being used as food both by the reindeer and by 
man. The Iceland Moss (( ‘etraria islandica) is abundant in North 
Britain, and the Cladinarangiferina (the Reindeer Moss), even reaches 
the southern counties of England, being abundant upon heaths in 
some parts of our own county, though not occurring very near 
Folkestone. This neighbourhood is good for the lichen collecter, 
as it is well known to be for the field naturalist generally. As 
there are grasses that grow in the sea, so there are inter-tidal 
species of lichen, but none have been observed on this coast. It is 
known that fungi cannot do with sea water, and this fact 
goes against the Fungus-alga theory. Generally speaking, 
lichens are not looked for in wet places at all, although they might 
be expected to abound there if the holders of the fungus-alga theory 
have truth on their side. But why, some enquiring member of this 
meting may ask, should not plants that live upon water live in 
water—why should they not be submerged or floating aquatic 
plants, and so be sure of constant supplies ? This question brings 
out facts of great interest, and which do not apply to any other 
class of plants, for the truth is that lichens live a life of a very 
peculiar kind. They grow fairly fast for a time and then move 
very slowly indeed, clinging to life through long periods of drought 
and under conditions that would be fatal to plant-life generally. 
Associated with this power of resistance, is length of days for it is 
startling to record that lichen life is not to be reckoned by hours 
(as with some Fungi), days, weeks, months. or even years, but by 
tens, and even, we are assured, hundreds of years. In hard times, 
it is very sluggish, the plants ‘‘ holding their own” bravely until 
better times come, when they revive and look young again. The 
