THE FUNGI. 



141 



THE LICHENS. PRACTICAL STUDIES. 



1. Observe Lichens in their natural locations on trees, 

 stones, fences, and the ground. Some, the crustaceous 

 Lichens, are so closely attached to the substratum that 

 they cannot be removed entire. Others, the foliaceous, 

 are attached in only a few places by rootlike processes 

 called rhizines (Fig. 80, r,r); 



the edges of the crustaceous 

 Lichens are more or less 

 curled or crinkled. Still 

 others, the fruticose Lichens, 

 are attached in only one 

 place, and rise in branching 

 shrublike forms from their 

 substratum. 



2. Find Lichens bearing 

 disk or cup-shaped spots. 

 These are the fructifications, 

 the apothecia. They will be 

 more minutely studied later. 

 At present find as many dif- 

 f erent kinds of Lichens bear- 

 ing apothecia as possible. 

 (See Figs. 78, 79, 82.) 



FIG. 80. A transverse section 

 through a foliaceous Lichen, not 

 passing through an apothecium; 

 o, epidermal layer of the upper 

 side ; g, the gonidial layer ; m, the 

 loosely arranged algal layer ; r, r, 

 rhizines. (Goebel.) 



3. Place pieces of any 

 foliaceous Lichen that is not 

 gelatinous between pieces of pith, and cut vertical sections 

 not passing through an apothecium. Mount in water. 

 The water causes the tissues to swell to such an extent 

 that it is not easy to make sections which will show all the 

 structures fully. A number of sections should therefore 

 be cut and the most favorable selected. 



Beginning at the upper surface, observe that the tissues 

 have become differentiated to form a more or less colored 



