DiDERMA 97 



5. Diderma spumarioides Fries, Syst. Myc. 3: 104. 1829. 



Didymium spumarioides Fries, Symb. Gast. 20. 1818. 



Diderma cinereum Morg. Jour. Cin. Soc. Nat. Hist. 16: 154. 1894. 



Plasmodium opaque white (Lister). Sporangia crowded, 

 forming large colonies, sessile, globose, 0.4 to 0.8 mm. diam., 

 smooth or rugose, white, often seated on or imbedded in a strongly 

 developed, white hypothallus; sporangial wall of two layers, the 

 outer fragile, composed of large, globular lime-granules, more or 

 less adhering to the membranous inner layer. Columella convex 

 or hemispherical, white or pale flesh-colored. Capillitium con- 

 sisting of slender, fiexuose, purplish threads, branching at acute 

 angles and anastomosing. Spores violet-brown, spinulose, 8-1 1 ju 

 diam. 



Type locality: Europe. 



Habitat: On dead leaves. 



Distribution: Common throughout North America in the 

 forested regions. 



Illustration: Lister, Mycetozoa ed. 3. pi. 84. 



The sporangia of the American form are smaller than those of 

 European specimens. The species as represented here has two 

 fairly distinct phases, distributed seasonally about equally, al- 

 though either form may appear at any time, and there are inter- 

 mediates. From May to July, the colonies usually have sepa- 

 rated sporangia and grayish smooth walls with less lime, little 

 hypothallus, and the capillitium more abundant. Later, the 

 prevailing developments have densely crowded sporangia with 

 thick calcareous walls, and a copious hypothallus in which the 

 sporangia are often imbedded. The early phase is probably 

 D. cinereum Morg., but there is no occasion for regarding the 

 differences as specific. The early fruitings come from the revived 

 sclerotium of the preceding winter, and the later ones from the 

 spores of the earlier sporangia. Similar seasonal differences may 

 be noted in other species of the Mycetozoa. Lime is found occa- 

 sionally in the capillitium of D. spumarioides. An extensive col- 

 lection made by Dr. W. C. Sturgis, in Colorado, has long, fusiform 

 lime-knots, and in many sporangia there are long, thin, flattened 

 or cylindrical columellae, sometimes bifurcate, and extending to 

 the tops of the sporangia. A collection, personally made in Pike 

 County, Pennsylvania, also has long, fusiform lime-knots in the 

 capillitium. A specimen from Corunna, Maryland, has lime in 



