148 OLAF GALL®E 
into it(Mentz, 1900; Sernander, 1901; Gallge, 1908 and 1913). The 
podetium-branch thus anchored forms new vertical branches, which 
in turn also die away below, etc. All the vertical podetium-branches 
and podetia, which are naturally very slightly attached to the ground 
(by the decaying bases), are mutually connected by numerous hap- 
tera, which hold them so closely together, that it is impossible to 
obtain uninjured any isolated podetium from a tuft. 
The characteristic features of this type are, that the primary 
thallus (here crustaceous) very soon dies, and that the podetia (at 
the edge of the tuft) may lie down horizontally and wander in this 
way, attached to the ground and to one another by haptera, while 
they die away at the base, and keep on living perhaps for centuries 
at their apex. 
The podetium-wanderer is an excellent earth-lichen-type, cap- 
able of competition beyond any of the others, by the fact of its 
dying away at the base, and keeping on growing at the apex, which 
enables it to grow above both crustaceous and foliaceous lichens, 
and also above hypothallus- and primary-scale-wanderers. The type 
is consequently exceedingly rich in individuals in nature; reindeer 
moss, as is well-known, is the most abundant earth-lichen in the 
world. But the type is poor in species. It is not adapted to life on 
rocks and trees, for its dying away at the base would deprive it of 
its substratum. 
The primary-scale wanderers are represented by Cladonia 
foliacea, which is in reality intermediate between a fruticose and a 
foliaceous lichen. The spore, on germinating, quickly forms a pri- 
mary thallus consisting of large, well-developed lobes, which spread 
out in a tuft-formation over the ground, while the hypothallus de- 
cays quickly. Along the edge of the tuft the lobes lie horizontally, 
but towards the centre they stand upright. They die away at the 
base, and keep on growing at the apex, exactly as in Cetraria, for 
instance. They are closely connected with one another by numerous 
haptera, which prevent them from being scattered to the winds. 
Consequently, so far, C. foliacea is a foliaceous lichen, but podetia 
may also be developed on the lobes of the thallus — although not 
frequently in Denmark or in Iceland — which makes it impossible 
to include it, as a matter of course, among the foliaceous lichens. 
The primary-scale wanderers, as regards their competitive capacity, 
are like the lower species of the erect foliaceous lichens; they are 
few in number both as regards individuals and species. The fact 
