8o 



MYCOLOGY 



Fig. 26. — A foHaceous lichen, Parmelia perlata. i, Plant slightly reduced in 

 size; a, apothecia; b, lobe of thallus; c, patches of soredia; 2, longitudinal section of 

 apothecium and cross-section of thallus; a, ascus; b, c, hypothecium; d, upper gonidial 

 (upper algal) layer; e, medullary layer;/, lower gonidial layer; g, lower cortical layer; 

 I, 3, cross-section of vegetative thallus. (From Gager. After Schneider.) 



