249 



nella varia overrun by the filaments of Cladonia pyxidata drawn 

 from specimens gathered at Fontainebleau. Occasionally goni- 

 dia are mixed with these filaments, in which case the latter are 

 bound to the ordinary thallus by a felt of liyph^, but it also 

 happens that a similar felt covers for a great length the ramifica- 

 tions of the protonema without the presence of gonidia. It 

 would seem from these circumstances that the spores of lichens 

 germinate without algae, and are able to await for a long time 

 the presence of this complement so indispensable to their organ- 

 ization by living as parasites on the protonemas of mosses. 



These observations led to a series of cultures attempting to 

 associate a fungus issuing from a spore of a lichen with the 

 protonema of a moss. The cultures were made as pure as pos- 

 sible on sterilized sand kept moist by water previously boiled 

 and protected from germs of the air. These cultures easily pro- 

 duced protonemas from the spores of the following mosses : Hyp- 

 niim cup res si for me, Barbida vuiralis, Fiinaria hygrometrica^ 

 Mntum hornum, Dicranella varia, and Phasciun ciLSpidatmn. 

 On these when well developed were sown the spores of lichens. 

 This is preferable to sowing both spores at once, as ordinarily 

 the lichens germinate more rapidly than the mosses. 



In studying the germination of the spores of Parmclia aipolia 

 on the protonema of Hyp man ciiprcssiforme, a pure cell-culture 

 on glass, the filaments of the lichen were seen to cover with a 

 regular network the ramifications of the protonema, extending to 

 the very tips of all the branches ; a similar culture of the spores 

 o{ Parinelia aipolia alone, under the same conditions, never hav- 

 ing produced a development comparable to that on the proto- 

 nema. In fig. 3 is represented another culture, that oi Barbida 

 mjiralis enclosed by a net- work of the filaments of Parmelia 

 physodes, forming a closer envelope approaching the formation 

 of a false tissue, analagous to that observed in certain lichens 

 where the gonidia are formed by filamentous al^ae, such as have 

 been so well described and figured by M. Bornet. 



In the case of Mjuicm horiium, which produces a protonema 

 with very large filaments, a singular development occurred, the 

 formation of propagules on the protonema of the moss in contact 

 with the lichen filament. On the more slender branches of the 



