QA8TBR0MTGBTE8. 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 

 hyphas. 



421. — In the curious little Oruciiulum 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 hyphse in its 

 centre ; this becomes cylindrical, and then undergoes several 

 remarkable changes. In the interwoven hyphse 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 hyphse, 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 rcL^eptacle, in which the sporangia lie 

 The sporocarp of Crucibulum is thus a much more highly 

 developeu 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 spore-bearing portion of the plant (sporocarp). 



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

 almost entirely unknown. 



(o) The principal genera of tlie Gasteromycetes are Phallus, which in- 

 clu'lesthe common Stink-horn ; Lycoperdon including several species o/ 



