GROUP I. THALLOPHYTA : FUNGI. 



297 



and is closed in the early stages of its development ; in the latter the 

 apothecium is borne on the convex, smooth, or reticulate surface of an 

 erect strorna. 



A 



FIG. 176. Clainceps purpurea. A A sclerotium (c) bearing stromata (x2). B Section 

 of a stroma ; cp the perithecia. C A perithecium more highly magnified. D An ascus 

 ruptured ; the elongated spores (sp) are escaping. (After Sachs.) 



The sub-order Pezizacese includes several families, the Phacidiese, 

 Pezizese, Bulgarieee, etc. As representative may be mentioned Rhytisma 

 Acerinum, the mycelium of which infests the leaves of the Maple, but the 

 development of the apothecium 

 does not take place until after the 

 leaves have fallen ; and other 

 similar forms which inhabit the 

 leaves of the Silver Fir, Spruce, 

 and other trees : Ascobolus, which 

 grows on dung : the various 

 species of Peziza, with brightly- 

 coloured apothecia, growing on 

 rotting wood, etc. : Bulgaria, with Fl - !?7. Longitudinal section of the 

 a gelatinous apothecium, growing a Pt h ecimn of Peziza convexula -. h the hy- 



menium. (After Sachs.) 

 on dead branches of the Oak. 



The sub-order Helvellaceae includes the genera Morchella (the Morell, 

 esculent), Gyromitra, Helvella, etc. 



