Mosses and Lichens 



whether they belong with the algae, with the fungi or have a 

 place as individual plants. 



It is claimed that with the microscope one may often deter- 

 mine the species of the associated fungus, as well as that of the 

 associated alga and that this alga freed from the lichen-fungus 

 pursues its normal mode of life and can then be identified. 



It is also claimed that lichens have been formed from the 

 spores of a fungus partner allowed to germinate on free-growing 

 algae, and that a variety of lichens have thus been developed and 

 that the same alga will produce different kinds of lichens if 

 associated with different fungi, and that spores of the fungus- 

 partner have been grown on nutrient solutions and have pro- 

 duced a fungus. One instance is known of a fungus-partner 

 (Cora pavonia) which can lead an existence independent of the 

 alga-partner. 



HOW A LICHEN IS MADE 



According to this theory, if a wandering fungus spore meets 

 a group of algal cells with which it can live in harmony, a lichen- 

 fungus-company may be founded on the spot. This lichen may 



grow and flourish and may from time 

 to time send forth representatives to 

 found new colonies. 



By another method, which is some- 

 what analogous to the budding of 

 higher plants, the partners for the new 

 colonies arise within the parent lichen 

 company. Certain groups of cells (So- 

 redia) separate from the rest, each group 

 consisting of one or more algal cells 

 enmeshed in a dense weft of fungus 

 hyphae. At the proper time the surface 

 of the parent lichen ruptures, and the 

 numerous social groups appear, giving 

 to the old lichen that attractive hoary 

 or frosted appearance they so often 

 have. With the aid of the wind these 

 easily travel, to form new companies. 

 The fungus spores (ascospores) which enter into partnership 

 with groups of alga cells are produced in sacs (asci, singular 



24 



Coccocarpia molybdia. A section 

 of the thallus showing the green 

 cells of the alga covered by the 

 colourless cells of the fungus. When 

 the lichen is damp the colourless 

 cells are more translucent and the 

 green cells show more and the 

 lichen is greener than when dry. 



