MUCILAGO 83 



frosted with stellate lime crystals, which mark in section the 

 boundaries of the several sporangia; capillitium of delicate 

 threads, generally only slightly branched, terminating in the 

 sporangial wall, marked with occasional swellings or thickenings. 

 By the descriptions offered by most authors, and especially 

 by Rostafinski's figures (Hon., PL ix.), a pronounced columella 

 is called for in the structure of Spumaria. The individual 

 sporangia rise from a common hypothallus, and occasionally 

 portions of this run up and give to a sporangium the appear- 

 ance of being stipitate. Sometimes also this upper extension 

 of the hypothalline protoplasm passes beyond or behind the 

 base of the sporangium or between two or more, and is more 

 or less embraced by these in their confluent flexures. This, 

 it seems, suggested Rostafinski's elaborate diagram, Fig. 158; 

 at least, none other form of columella is shown by American 

 materials at hand. 



i. MUCILAGO SPONGIOSA (Leyss.} Morgan. 



1783. Mucor spongiosus Leysser, Fl. Hal., p. 305. 



1791. Reticiilaria alba Bulliard, C. Fl. France, p. 92. 



1791. Spumaria mucilage Persoon, Gmel., Syst. Nat., II., p. 1466. 



1805. Spumaria alba (Bull.) DC., Fl. Fr., II., p. 261. 



1897. Mucilago spongiosa (Leyss.) Morgan, Bot. Gas., XXIV., p. 56. 



white or cream colored, of variable size and shape, 

 half an inch to three inches in length and half as thick, the 

 component sporangia resting upon a common hypothallus and 

 protected by a more or less deciduous calcareous porous cortex ; 

 peridial walls thin, and where exposed iridescent, generally 

 whitened by a thin coating of lime crystals ; capillitium scanty, 

 of simple, mostly dark-colored, slightly anastomosing threads ; 

 columella indefinite or none ; hypothallus white, spongy ; spore- 

 mass black, spores violaceous, exceedingly rough, large, 10-15 /i. 

 Very common in all the eastern United States and the 

 Mississippi Valley, south to Texas. The plasmodium is dull 

 white, of the consistence of cream, and is often met with in 

 quantity on beds of decaying leaves in the woods. In fruit- 



