38 INTRODUCTION TO THE STUDY OF FUNGI 



a compact hymenium. The substance of the cup and entire 

 Fungus is most often soft and fleshy, and therefore they are 

 more or less hygrometric, closing when dry and expanding 

 when moist. Whether naked or clothed with hairs, the 

 exterior is usually dull and sombre-coloured, so as scarcely to 

 be distinguished from the matrix on which they grow. A 

 similarly-shaped receptacle is to be found in CypheUa amongst 

 the Hymenoraycetal Fungi, in Cyathus and Crucihuluon 

 amongst the Gastromycetes, and in Aecidium amongst the 

 Uredines ; besides partial resemblances amongst the Siihaerop- 

 sidcae, and a few of the compact moulds, such as Volutclla and 

 Chactostroma. The closing of the margins of the cups, and 

 the long marginal hairs which in dry weather cover the 

 hymenium, serve as a protection against evaporation, to which, 

 from their fleshy substance and exposure, they are peculiarly 

 liable. Some minute species, which are erumpent, retract 

 themselves within shelter of the cuticle as they lose their 

 moisture, and can only be distinguished with difficulty. 



Another form of receptacle is represented by thousands of 

 species, and that is the ijcrithccnim. This is a minute form, 



#^^ seldom exceeding a rape-seed in size, 



yT ;= ^^V ^^^^^ usually very much less. It may 

 C-'^/:!^! be characterised as a globose flask 

 \& ^iii^^ g^ with a very short neck, but this 

 Fio. 20.— Peritiieciuiii witii iomi is variously modified (Fig. 20). 

 '''''^^*'°"- Sometimes it is seated directly upon 



its mycelium, and sometimes simk in a stroma which 

 arises from a mycelium. These receptacles may be superficial, 

 on the surface of the matrix, or either wholly or partially 

 immersed. The globose form may be flattened at the 

 base, and the neck be very much elongated, like a horn, or 

 absent altogether ; and. they may grow singly or in company. 

 In some genera the perithecium is soft and fleshy, and then 

 pale or brightly coloured, as in Nedria. It may be thin and 

 membranaceous, as in Sphaerella ; or it may be coriaceous and 

 tough, as in Botryosphaeria ; or carbonaceous and brittle, as in 

 Rosellinia. Externally it may either be smooth and shining, 

 or mealy, or warted, or bristly, or woolly. The apex is always 

 closed, except for a minute pore or ostiolum, and this is only 



