266 



POPULAR HISTORY OF LICHENS. 



analogy renders the fistalose podetium, in the opinion of 

 some authors, of superior rank or value in classification to 

 the solid branched stipe of Stereocaulon and Splicer ophor on. 

 The thecse and paraphyses in this genus are very small and 

 indistinct. The spores vary little in different species, except 

 in size ; they are usually very minute, — among the smallest of 

 lichen -spores, — ellipsoid, oval, or oblong, simple and colour- 

 less or very pale yellow. The spermatia also are similar 

 throughout the species. The colour of the apothecia is 

 generally scarlet or brownish, in both cases depending, ac- 

 cording to chemists, on the oxidation, or other reactions and 

 metamorphoses, of the colorific principle termed Usnic acid, 

 in combination with bases. When dry, the podetia are often 

 very friable, crumbling into dust by the slightest pressure ; 

 but moisture immediately renders them again quite flaccid. 

 In their rudimentary or abortive state the Cladonics often 

 present the characters which we have described under the 

 genus Lepraria* 

 * Turbinate podetia scyphiferous ; cylindrical ones entire 

 (or imperforate) at axils of ramules. 

 t Apothecia scarlet. 

 L Cladonia Extensa (extendo, to dilate). Podetia at 

 * Hampe on the Cladonias of the Hartz, in the Annales des Sc. Nat., vol. ix. 



