54 



A liolien is a vlant complex, made up of Algae and Fungi. 

 Three -tilings to be considered. 



1. Relation of wixole to what it is attached. If on a tree it must 

 be an epiphyte or saprophyte. Both theories held, but neith-^r 

 proved absolutely. 



2. Relation of Alga to I'^Uiigus. 



3. Relation of Pungris to Alga. 



(a) An&tomy — old view — that Alga and Fungus were derived from same 



source. This disproved. Experiments have been made by which lichens 

 have beenraade, showing the two plants absolutely independent. 



(b) Mutualism — 2d view. 



(c) Parasitism . 



Fungus must be benefited. As to the Alga, it is an open question. 

 An equal case seems to be able to be made out both for parasitisii 

 and mutualism. Lichens are xerophytes, but Algae and Fungi are 

 largely hydrophytes. This seems a proof on the side of mutualism. 



Soredia — a means of reproduction, composed of a few hyphae of 



II 

 i'\ingi and a few Alga cells which is not unlike a gemma — given off { 



by the lichens. 



(d) Helot ism 



Half way between the two — T/arraing. 



2. Holdfast Organs . 

 Roots are decidedly holdfast organs, also rhizoids and root-hairs. = 

 Tamaracks have not a good opportunity for vertical root develr^pnent. 



