DIDERMA 127 



violaceous, distinctly warted, 12-15 fx. Plasmodium at first watery, 

 colorless, becoming at length milky white. 



The didermas are generally delicately beautiful. The outer wall in 

 the present species is like finest unglazed china, softly smooth, and yet 

 not polished, often absolutely white, with porcellanous fracture. An 

 interparietal space separates the outer from the inner wall, so that the 

 former may be broken, bit by bit, without in the least disturbing the 

 underlying structure. The inner wall is ashen or gauzy iridescent-green, 

 sending back all colors in reflected light. The spores are violet, deeply 

 so when fresh, the capillitium strong and likewise tinted ; the columella 

 passing down and blending with the common snow-white hypothalline 

 base. In the Lister monograph included with D. globosum but the 

 two species are distinctly different in habit. In the one the distinct 

 sporangia are associated but not crowded; in the other all are massed 

 together, forming chalky masses of considerable size, 2 or 3 cm., over- 

 crowded, superimposed, where the sporangia are irregular in shape and 

 size by reason of mutual pressure. The plasmodium develops in forests 

 and orchards, among decaying leaves, but is inclined to rise as maturity 

 draws near, to ascend some erect twig, or the stem of a living plant to 

 the height of several inches where the sporangia at length appear 

 "heaped and pent," an encircling sheath, conspicuous after the fashion 

 of Mucilago, for which it is indeed sometimes mistaken. 



Common. Distinguished from the following species by the larger 

 and more distinctly marked spores and the more crowded habit. 

 New England and Ontario west to Nebraska; Europe. 



The species reported from Manchuria by Skvortzow (1931), as 

 D. globosum, is said to have spores 1 1-1 1.5 n. It is probably this species. 



8. DlDERMA GLOBOSUM PerS. 



Roemer N. Mag. Bot. 1 : 89. 1794. 

 PL IX, Figs. 188, 189. 



1804. Reticularia globosa (Pers.) Poiret, in Lam. Encycl. 6 : 182. 



1827. Cionium globosum (Pers.) Spreng., Syst. Orb. Veg. 4 : 529. 



1875. Chondrioderma globosum (Pers.) Rost., Mon. 180. 



1876. Chondrioderma off ine Rost., Mon. App. 18. 

 1876. Chondrioderma similans Rost., Mon. App. 20. 



Sporangia more or less closely gregarious, sessile, globose or by mu- 

 tual pressure prismatic or polyhedral, white, the outer wall smooth, 

 polished, crustaceous, fragile, far remote from the inner, which is 

 thin, smooth or rugulose, iridescent-blue; hypothallus usually pro- 

 nounced and spreading beyond the sporangia, sometimes scanty or 



