FUNGI AND LICHENS. 



125 



been employed by the peasantry of Scotland and 

 Ireland as a domestic dye-stuff for stockings and yarn. 



We have lichens of still another form, 

 which is represented by the somewhat 

 rounded bright-yellow patches which ad- 

 here closely to barn-doors, old rails, apple- 

 trees, and the trunks of various forest 

 trees. 1 In this instance the thallus, or 

 leaf-like stratum, is more or less rounded 

 at first, but often confluent and irregular, 

 adhering closely and firmly, with the sur- 

 face raised in warts and folds. The cups 

 are darker coloured, freely scattered over 

 the surface. There are many lichens of 

 this type; some are greenish-grey, some 

 bluish-grey, some brownish. The cups, 

 too, are different in colour, sometimes 

 with very bright tints. Having made 

 the acquaintance of the wall lichen, any of 

 these forms will at once be recognized as 

 lichens. Even at the present day some 

 lichens are still marketable commodities 

 as affording a dye, but the discovery of 

 aniline dyes has much restricted their use. 



The thallus, or substratum, is reduced in 

 some lichens to merely a powdery white 

 patch on the bark of trees, and upon this 

 the fruit-cups are seated. These latter no 

 longer retain the form of cups, but be- OPEG RAPHA 

 come elongated, and closed above, with a SCRIPTA. 



If. 



1 Parmelia parietina. 



