150 OLAF GALL@E 
they are lying interwoven with the hyphæ-bundles, it cannot be 
shown that the hyphæ affect them. I have observed them very 
commonly in Cladonia pityrea, squamosa, crispata and Floerkeana. 
Plant-remains, with their structure intact, occur very commonly 
in the hypothallus. Thus I have found Cladonia pityrea adhering 
to the bark of a dead heather-twig. The hyphæ of the hypothallus 
behave here exactly as does the hypophloedal hyphal system in the 
bark-lichens: The cork-lamellæ were split from one another into 
small-scales, but the cork could not be proved to have been cor- 
roded by the hyphæ. The same lichen often spreads out its hypo- 
thallus over dead moss-leaves on the ground, but these have, as a 
rule, turned so brown and are so broken, that it cannot be shown 
whether the hyphe have had any part in their disintegration. 
Very commonly the hyphæ encounter various green algæ and 
Cyanophycee (Gloeocapsa, etc.); in no case did I find haustoria in 
the algæ, nor did I, on the whole, see the hyphe attach themselves — 
to the alge, or by their mode of branching, etc. show the least 
interest in the alge in question. They appear almost always to be 
of no importance whatever to the lichen-hyphæ, even if they are 
lying encysted amongst them. The fact that dead specimens may 
be found amongst them does not show with any certainty that death 
is due to any influence exerted by the lichens, although the pos- 
sibility of it is not excluded. 
The primary thallus (in Cladonia) consists, as is well-known, 
of small, leaf-shaped thallus-scales of dorsiventral structure, which 
proceed directly from the hypothallus, and are developed in centri- 
fugal succession from it. In all hypothallus-wanderers the primary 
scales live very long as “nutrition-shoots,” co-equal with the podetia. 
They are of far less importance to the more primitive podetium- 
wanderers (Cladonia gracilis, furcata, rangiferina) in which the 
podetia, at an early stage in the plant’s life, become its chief, and 
finally its only assimilatory organ; finally, in the more advanced 
podetium-wanderers (Cladonia rangiferina, uncialis), they are so in- 
significant, that they form quite a crust-shaped thallus, which perishes 
so early, that the majority of the lichenologists have not even seen 
it. Moreover, several podetium-wanderers are, as a rule, propagated 
in quite a different manner (by fragments of podetia, etc.) and thus 
have, on the whole, very rarely any opportunity of developing a 
primary thallus. 
