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LICHENOLOGY OF ICELAND 155 
degenerans, uncialis, Thamnolia vermicularis, Cornicularia aculeata, 
Bryopogon jubatus v. nitidulus, Sphærophorus fragilis; they play ex- 
actly the same råle as do apical haptera put into other species. 
Primary-scale haptera I found only in Cladonia foliacea. By 
means of them the primary scales of long duration which die away 
at the base, are attached to one another; no parasitic relation arises 
by this attachment. 
Podetium-scale haptera I found only in Cladonia cornuta. 
By means of them the podetia are attached to one another, the scales 
of the one podetium attaching themselves to the wall of another 
podetium of the same species; no parasitic relation arises by this 
attachment. 
When procumbent podetia are buried in the ground, they die. 
No species known to me can endure being covered with earth for 
a long time. First the gonidia appear to die, sometimes after a short 
period of intense division, which is probably occasioned by the 
increased dampness. Then the lichen-hyphæ die, the walls, as a 
rule, turning brown. 
The fruticose earth-lichens are propagated in a widely different 
manner according to their morphological structure. Hypothallus- 
wanderers very commonly bear fruit, and are propagated, no doubt 
as a rule, by ascospores. Some of them are propagated far more 
frequently by soredia, and in that case apothecia are much rarer 
in them (Cladonia fimbriata, deformis), so that in such species there 
appears to exist a correlation between these two modes of propa- 
gation. In others again these two modes of propagation appear to 
be equally common, a quantity of soredia and apothecia being de- 
veloped on the same individual. However it requires to be more 
closely investigated, whether the asci in strongly soredia- bearing 
individuals are empty, as they frequently are in Cladonia. 
In the podetium-wanderers propagation takes place in several 
cases by the breaking off of fragments of podetia which are then 
carried away by the wind to other places where they form new 
tufts. This has already been described by Wainio (1898) and after- 
wards mentioned by Mentz (1900) and Gallge (1913 and 1918). 
Species of Sfereocaulon do not appear to be able to propagate 
themselves in this way, as podetia-fragments have not yet been 
observed to put out haptera into the ground. On the other hand, 
they are often found bearing apothecia. 
Of fruticose earth-lichens Iceland has the following: — 
