114 PRACTICAL BOTANY. 



2. The margin, which is hardly developed as a 

 distinct excipulum. 



3. The lower surface and base, which is usually 

 covered with fine hyphal filaments, serving as rhizoids. 



From material, either quite fresh, or hardened in 

 alcohol, cut median vertical sections : mount in glycerine, 

 and observe 



1. The large-celled pseudo-parenchyma about the 

 lower surface, with the projecting rhizoid-like hyphae 

 which penetrate the substratum. 



2. Passing upwards through the section the hyphal 

 character becomes more obvious, the branched filaments 

 forming a dense plexus. 



3. The tissue again assumes more of a pseudo- 

 parenchymatous nature in the subhymenial layer. 



4. The hymenium, which is similar in its character 

 to that of Parmelia, consisting of 



a. Elongated, narrow paraphyses, and 



I. Wider asci, each of which contains eight spores. 



A careful comparison of various asci will give some idea of the 

 mode of development of .the spores by a process of free-cell 

 formation. 



Other forms of Ascomycetous Fungi may also be compared 

 with advantage ; e.g. Morchella (the Morel). 



