432 Notes on Parasitic Ascomycetes. — //. [Sess. 



brittle as readily to drop from the parent trunk to the ground, 

 where a host of other fungi soon combine forces to hasten the 

 processes of disintegration and decay. In late autumn and 

 early winter, too, nearly every dead herbaceous stem or 

 withered leaf affords a congenial habitat to one or more 

 species of Pyrenomycetes, which appear as black dots scattered 

 over the surface or partially concealed beneath the epiderm. 

 In their early state of development many of these micro fungi 

 produce perithecia, which are destitute of asci but contain 

 conidia produced at the tips of simple or branched conidio- 

 phores. In some species these perithecia so closely resemble 

 the mature ascigerous ones as to be practically indistinguish- 

 able without the aid of a microscope. 



The Pyrenomycetes resemble the Perisporiaceae in having 

 their asci produced in the interior of hollow receptacles or 

 ascophores known as " perithecia." These may be compared 

 to tiny nuts, of which the shell is represented by the outer 

 wall of the perithecium, and the kernel by the group of asci 

 contained within it. The perithecium of a true Pyrenomycete, 

 however, is furnished with an apical opening through which 

 the spores are emitted when discharged from the asci. Some- 

 times the perithecium has a more or less elongated beak 

 through which the spores make their exit, but more frequently 

 the opening for their liberation is in the form of a minute 

 perforation or simple pore leading direct from the internal 

 cavity to the surface. The external wall or integument is 

 very often of a hard or carbonaceous consistency and black 

 colour ; but in some species it is leathery or fleshy, and in 

 some is brightly tinted with shades of red, yellow, or brown. 

 The perithecia are often solitary, or sometimes grouped or 

 clustered, or produced on the surface of a densely compacted 

 cushion-like mass known as a " stroma," or immersed partially 

 or wholly in the substance of the stroma itself. In certain 

 genera the asci in the perithecium are intermingled with 

 barren threads known as " paraphyses." These are usually 

 of a filiform, needle-shaped, or clavate pattern; and their 

 comparative size and shape often afford features whereby the 

 various species may be distinguished from one another. 



Although the Pyrenomycetes constitute one of the largest 

 families of microfungi, yet comparatively few species fall to 



