26 



THE GUIDE TO NATURE. 



numerous bright green globular bodies 

 surrounded by slender colorless 

 threads. Many facts go to show that 

 the green globules are tiny algae or 

 seaweeds such as ordinarily grow on 

 moist rocks or bark, while the threads 

 surrounding them belong to a sort 

 of fungus somewhat like a mushroom 

 which being unable to make any food 

 for itself, because of its lack of the 

 necessary Green coloring matter, feeds 

 upon the green algae it has imprisoned. 

 But for the food it takes from the algae 

 the fungus makes good return by af- 

 fording them protection, keeping" them 

 moist, screening" them from too much 

 light, and providing them with all the 

 materials they need for making more 

 food than they require for their own 

 use. Hence we find the algae within 

 the lichen often, growing more vig- 

 orously than the same kind does when 

 Hying free. The result is that these 

 cooperatiye communities we call 

 lichens are able to thrive in situations 

 where no other plants can liye. "When 

 bare rock is exposed on a mountain 

 side lichens are the first forms of life 

 to gain a foothold. Particles of dust 

 caught by them accumulate as a slight 

 soil which may support true mosses 

 that in turn may catch more soil and so 

 in time prepare for the coming" of little 

 herbs or shrubs or, finally, a mighty 



forest. Thus lichens are Nature's 

 pioneers. They do not need any 

 soil to grow upon although they are 

 often found upon soil of yarious kinds. 

 Clean air, sunlight, moisture, and a 

 place to cling to are about their only 

 requirements. Accordingly, in the 

 case of these cup lichens found with 

 the moss suspect that it was the 

 lichens which arrived first, and that 

 the moss came to live with them. 



I dare say the moss was perfectly 

 welcome. Cup lichens are used to 

 such neighbors. Indeed, it may not 

 be too much to say that long associ- 

 ation with mosses perhaps brought 

 about the making of cups wherebv the 

 lichens are enabled to catch some extra 

 moisture and at the same time to hold 

 their fruits sufficiently high for letting" 

 breezes carry off the minute spores 

 by means of which the plant is spread 

 abroad. As for the mosses growing 

 over tltem — two can play at that game; 

 and we often find little lichens cling- 

 ing to mosses as if they could stand 

 the arrangement as long as the moss 

 could. 



The exceptionally lovely coloring of 

 lichens to which your correspondent 

 refers and well compares to a pastel, 

 is I believe too seldom appreciated. 

 Her remark recalls some of the de- 

 lightful surprises I have had in ex-' 



A CLUSTER OF CUP LICHENS OX A ROCK 



