GASTEROMYCETES. 325 



Earth-star the outer peridium, which is dense, and when dry 

 quite hard, splits from the top into partially separated seg- 

 ments, which recurve and expose the inner more delicate perid- 

 ium ; the latter ruptures more or less regularly at the top, and 

 thus allows the escape of the spores and dusty broken-up 

 hyphae. 



421. In the curious little Crucibulum and its allies the 

 structure and mode of development are much more compli- 

 cated. The mycelium, which grows over the surface of de- 

 caying wood, forms first a rounded mass of hyphae in its 

 centre ; this becomes cylindrical, and then undergoes several 

 remarkable changes. In the interwoven hyphae of the inte- 

 rior, at certain points, there is a very great increase in the 

 number of hyphae and the density of the tissue ; this takes 

 place with such regularity that several round bodies are 

 formed. The interior of each of these round bodies is at 

 first composed of interwoven hyphae, but these become mu- 

 cilaginous, and finally entirely dissolved, forming a central 

 cavity in each mass ; into these cavities hypha-branches now 

 grow, and line them with an hymenial layer of spore-bearing 

 basidia. The round bodies are thus sporangia. While the 

 above-described changes are going on, the tissue lying between 

 the sporangia undergoes conversion into mucilage, and be- 

 comes entirely dissolved, leaving only a surrounding wall 

 (the peridium), and slender pedicels composed of hyphae, 

 which support the sporangia. When these changes are com- 

 pleted, the peridium ruptures at the top and opens out, 

 forming a cup-shaped receptacle, in which the sporangia lie. 

 The sporocarp of Crucibulum is thus a much more highly 

 developed organism than that of Lycoperdon, although not 

 differing from it in any essential point of structure. 



422. No sexual organs have yet been discovered in the 

 Gasteromycetes, but analogy points to their probable exist- 

 ence upon the mycelium just previous to the first appearance 

 of the gpore-bearing portion of the plant (sporocarp). 



423. The mode of germination of the spores is as yet 

 almost entirely unknown. 



(a) The principal genera of the Gasteromycetes are Phallus, which in- 

 cludes the common Stink-horn; Lycoperdon including several species of 



