Lichenes. 247 



between the liehen and the symbiotic alga are erroneous, and that 

 the liehen is a fungus pure and simple. 



7. The foUowing are the main arguments against mutualism. 

 Lichens commonly grow where there are free algae of the same 

 speeies as those parasitized by these lichens. The spores of the 

 lichens germinate and attaek the free algae as other fungi attack 

 their hosts. Lichens perform like other fungi on eulture media and 

 may be made to produce their reproductive organs on these media. 

 Their development on such media does not differ from that reached 

 when growing with their algal hosts more than other fungi vary 

 from their usual appearanee when grown on eulture media. Liehen 

 spores also attack the algal hosts, when the spores and the algae 

 are introduced into cultures together; and the resulting liehen is 

 normal and sometimes fruetifies in the cultures. Algal hosts extrac- 

 ted from liehen thalli grow in cultures like free algae of the same 

 speeies grow on similar eulture media. Some lichens live for years 

 in their substrata outside the relation with their algal hosts. The 

 researches of Elenkin and Danilov prove that liehen hyphae 

 absorb food from the algal host eells, which are killed by severe 

 parasitism or more probably by parasitism and saprophytism com- 

 bined. The relation of the Liehen to its substratum proves that 

 higher lichens can take comparatively little food from it and must 

 depend more than lower Lichens upon the algal hosts; and this 

 shows that the parasitism of the liehen upon the algal host has 

 become more severe in the evolution of higher lichens. Finally, the 

 algae parasitized by lichens are in a disadvantageous position with 

 reference to carbon assimilation. 



8. The following are the main arguments for the fungal nature 

 of lichens. Lichens are like other fungi with respeet to vegetative 

 strueture and fruiting bodies. The bridges which conneet lichens 

 with other fungi are not few but many. Since it is thoroughly 

 deraonstrated that the liehen is parasitic, or partly parasitie and 

 partly saprophytie on the alga, there is no longer even a poor 

 exeuse for a "consortium" or an "individualism" hypothesis. 



9. The parasitism of Lichens on algae is peeuliar in that the 

 unieellular or the filaraentous hosts are usually enelosed by the 

 parasite, which may carry more or less food material to its host. 

 The host inside of the parasite is plaeed in a disadvantageous Posi- 

 tion with reference to carbon assimilation and may depend. for its 

 carbon supply, more or less upon material brought from the sub- 

 Stratum by the parasite. Some algal individuals not yet parasitized 

 may be found in most liehen thalli. 



10. The liehen is a fungus which lives during all or 

 part of its life in a parasitic relation with the algal host 

 and also sustains a relation with an organie or an inorga- 

 nie substratum. The definition may need modifieation later to 

 recognize Elenkin's hypothesis, in part or fuUy. Maxon. 



Hasse, H. E., Additions to the liehen flora of southern 

 California. VIII. (The Bryologist. XVI. p. 1-2. January, 1913.) 



Includes deseription of Maronea constans var. suhlecideina A- 

 Zahlbr., var. nov., from the Santa Monica ränge; and Derniatocar- 

 pO)i [Endopyrenium) Zahlbmcknevi Hasse, sp. nov., also from the 

 Santa Monica ränge, California. Maxon. 



