CHAPTER IX. THE THALLOPHVTA. 325 



on the walls of which the basidia are borne. In many species 

 the number of spores on each basidium is eight, but in some 

 there is the usual number, four. 



The Lycoperdaceae, the Hymenogastreae, the Nidularieae and 

 the Phalloideae, form the subdivisions of the group. The Lyco- 

 perdaceae include the Puff-balls and Geasters or Earth-stars. 

 The rounded sporocarps of the former produce innumerable 

 brown spores, which are discharged in clouds by the scaling 

 away of the outer periderm, and the rupturing of the inner one. 

 The latter are similar, except that the tough outer periderm sep- 

 arates into regular segments, which flatten out into a star-like 

 form. 



The Hymenogastreae are subterranean fungi, resembling, in 

 their habits, the Truffles. In most of the other species of the 

 group the walls of the chambers, constituting the supporting 

 frame-work for the hymenium, undergo great changes during the 

 development of the sporocarp, for example, in the Lycoperdons 

 the chambers disappear, leaving only a loose frame-work of 

 threads ; but in the species of this group they remain unchanged 

 until the ripening is complete. The spores are finally set free 

 by their decay. 



The Nidulariea or Bird's-nest Fungi (see Fig. 526), form 

 cup-shaped sporocarps, which, when ripe, open at the top, 

 exposing several rounded hard bodies, which look something 

 like eggs in a nest. The hard bodies are the spore-bearing 

 chambers which have become isolated^ in the process of devel- 

 opment. 



The Phalloideae are at first rounded, but in development, the 

 peridium, which consists of three layers, bursts and exposes a 

 chambered spore-bearing area which is elevated on a stalk. 

 The hymenium soon becomes a dark-colored and foul-smelling 

 mucilaginous mass in which the spores are inclosed. The spores 

 are scattered by carrion- flies, which are attracted to the plants 

 in large numbers by the smell. 



The Hymenomycetes are a numerous and important group 

 resembling each other in the fact that at the time the spores are 

 ripe, the hymenium occupies the outer free surface of the sporo- 

 carp, and not its interior. The plants differ much among them- 

 selves as respects the shape of the sporocarp and the form and 



