20 TALKS AFIELD. 



lating. These granules, or gonidia, are rep- 

 resented by the black dots in Fig. 22. A 

 peculiar discussion has 

 arisen in late years, in 

 regard to the true nature 

 of these gonidia, and 

 some botanists contend 

 that they are not a part 

 of the lichen at all, but 

 are algae, and that the surrounding gray por- 

 tion is a fungus which draws its nourishment, 

 in a parasitical way, from these algae. This 

 view does away with the great group of 

 lichens, and resolves these plants into fungi 

 which are parasitic on or about algae. We 

 will follow the old and common method, 

 however, of calling these plants, with their 

 gonidia, lichens. Lichens are reproduced 

 by means of spores in very much the same 

 manner as many fungi. Of all visible 

 plants, lichens possess the power of adapting 

 themselves to the widest differences of cli- 

 mate and surroundings. They are at home 

 under the snows of the polar regions, and 

 equally so iu the burning sun of warmer cli- 

 mates, where they wither in drouth and re- 

 vivify in rain. They increase as we travel 

 northward or southward from the equator. 



