150 OLAF GAI.I.0K 



they are lying interwoven with the hyphae-bundles, it cannot be 

 shown that the hyphoe affect them. I have observed them very 

 commonly in Cladonia pityrea, sauamosa, 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 hyphae of the hypothallus 

 behave here exactly as does the hypophloedal hyphal system in the 

 bark-lichens: The cork-lamellse were split from one another into 

 small-scales, but the cork could not be proved to have been cor- 

 roded by the hyphae. 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 hyphae have had any part in their disintegration. 



Very commonly the hyphae encounter various green algae and 

 Cyanophycece (Gloeocapsa, etc.); in no case did I find haustoria in 

 the algae, nor did I, on the whole, see the hyphae attach themselves 

 to the algae, or by their mode of branching, etc. show the least 

 interest in the algae in question. They appear almost always to be 

 of no importance whatever to the lichen-hyphae, 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, fnrcata , ranyiferina) 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, nncialis), 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. 



