120 



CAEPOASCI. 



parenchymatous covering of the ascocarp, enclosing one (Podo- 

 sphcvra and Sphcerotheca ; compare Thelebolus among the Hemi- 

 asci) or a few asci (Fig. 108 c), which do not form any hymenium, 

 but are irregularly placed. The cells of the ascocarp-envelope 

 are often prolonged into hair-like appendages. The ascocarps are 

 developed from the mycelium at places where two hyphre cross 

 each other (Fig. 107). At these places two short and erect hyphse 

 are produced side by side. The one from the lower hypha (Fig. 

 107 c) assumes an ellipsoidal shape, and is cut off by a transverse 

 wall to form the oogonium -while the other (6) arches over, and 



FIG. 108. Erysiplie comm urn's. A small portion of a leaf with this Fungus growing upon, 

 it (ccrasi'ierably magnified). The hypbae b and d do not belong to this Fungus, but are re- 

 productive organs of a pyrenomycetous Fungus parasitic upon it (Cicinnobolas) . 



from its apex the true antheridium is cut off (Fig. 102A). The 

 nucleus from the antheridium passes into the oogonium, and unites 

 with its nucleus. After fertilization the oogonium becomes multi- 

 cellular, and is known as the ascogone. In Sphcerotheca the binu- 

 cleate penultimate cell produces the ascus, but in other genera it 

 branches and gives rise to numerous asci. Hyphal branches from 

 the base of the ascogone surround it and form the envelope of the 

 ascocarp (perithecia). 



Many plants, both cultivated and wild, are attacked by various 



