250 



protonema, where the ramifications of the lichen were more dense, 

 there were formed dilations clinging to the protonema, and here 

 a curious phenomenon took place. The protonema swelled, form- 

 ing a bud, in which accumulated a dense mass of protoplasm and 

 threw across a partition, at the same time thickening its walls. 

 Two or three months later, when all the rest of the cultures had 

 disappeared, these "propagules" remained and later on germi- 

 nated on a moist surface, producing the protonema of Mnttim 

 without the least trace of a lichen. This seems a remarkable 

 mode of defence of the moss against the encroachments of the 

 lichen filaments. 



Never in all the cultures has the author seen fructification 

 (apothecia, gonidia or other) on the filaments of the lichens, and 

 ordinarily the cultures ended in the destruction of the protonema, 

 on which the lichens seemed to act like a parasite. This partial 

 asssociation, as in nature, seems to aid the lichen to germinate, 

 permitting it to live during a time long enough to develop its 

 filaments and search for the alga which would constitute its 

 gonidia. 



The development of these filaments was also observed on the 

 leaves of mosses and hepatics, covering them with a false tissue; 

 but the lichen does not develop definitely unless associated with 

 algae on the surface of the leaves of mosses. This was observed 

 in the case of Lecidea vernalis, whose spores had germinated on 

 the surface of a leaf of Dicranella varia which was found ovi the 

 surface of a rock. After the filaments had developed and formed 

 a net- work enclosing the leaf, their ramifications had encountered 

 an alga and formed gonidia, constituting the ordinary associa- 

 tion of the lichen, grafted, as it were, upon a moss. 



Numerous such cases were observed on the leaves and stems 

 of Poly trie Jium, Dicramim, Mniiim, Hyp)iums, Leskea, Jiinger- 

 mannia^ Radiila^ etc. It happens quite frequently at the base of 

 rocks or beneath the stones along shady roads, as well as in the 

 sub-alpine zone of the Alps and Pyrenees. Wherever mosses 

 may be seen surrounded by various species of lichens, these 

 may readily be observed germinating and following a similar 

 evolution almost to the complete destruction of the mosses. 



E. G. B. 



