84 ENDOSPOREAE [PHYSARUM 



Var. 1. — obscurum Lister : sporangia sessile, 0-4 to 0-8 mm. 

 diam., subglobose or forming plasmodiocarps, gregarious 

 or crowded, greenish-grey, often spotted with pale yellow 

 or olive-brown, somewhat glossy; sporangium-wall mem- 

 branous, colourless above, yellow at the base, either without 

 lime, or with widely scattered clusters of whitish lime- 

 granules : lime-knots bright yellow : spores 6 to 8 /x diam. 



Var. 2. nitens Lister : sporangia subglobose, 0-5 to 0-8 mm. 

 diam., sessile, gregarious, not clustered, bright yellow : spores 

 7 to 9 (l diam. — Macbr. N. Am. Slime-Moulds, 34. P. luteolum 

 Peck in Rep. N. York Mus. Nat. Hist,, xxx. 50 (1878) ? ; 

 see Sturgis in Trans. Conn. Acad., x. 470 (1900). P. auris- 

 calpium Macbr. (non Cooke) in Bull. Nat. Hist. Iowa, ii. 

 158 (1893). 



PI. 61. — a. sporangia (Essex) ; b. capillitium and spores, with fragment of sporan- 

 gium -wall, showing three calcareous discs; c. spore; e. sporangia of var. 

 obscurum (Devon). 



PI. 62. — var. nitens ; a. sporangia (Maine) ; b. capillitium and spores, with 

 fragment of sporangium- wall ; c. spore. 



Glycerine mountings of the typical form show, dispersed in the 

 sporangium-wall, flattened disc-shaped crystalline bodies with a radiat- 

 ing structure, measuring 10 to 20 /x diameter ; these are also found in 

 the sporangium-wall of P. psittacinum, P. dictyospermum, and Graterium 

 leucocephalum ; they do not appear to be present in vars. obscurum 

 and nitens. Through the courtesy of Professor Macbride we have 

 received a specimen of the form he has published as P. theioteum Fr. 

 (B.M. 2329) ; the small golden-yellow sporangia are on dead wood, 

 and crowded, not heaped, on a membranous hypothallus ; the sporan- 

 gium-walls with their characteristic " discs," the capillitium and spores 

 are those of typical P. virescens. The var. obscurum has been found four 

 times in England, and has also been recorded from Scotland, Hungary, 

 and the Adirondack Mts., New York ; the capillitium and spores are 

 similar to the typical form, but in external appearance it differs markedly 

 in the larger and often scattered sporangia with glossy and almost 

 limeless walls. The var. nitens is a handsozne form, having rather larger 

 sporangia than the type, with which it is connected by gatherings 

 intermediate in character. Dr. Sturgis has examined the scanty and 

 injured remains of the type of P. luteolum Peck in the New York State 

 Museum at Albany ; he regards it as being probably P. virescens var. 

 nitens, and considers that Peck's name should be discarded (see 

 Sturgis I.e.). 



Hab. On dead leaves, moss, etc., more rarely on wood. — Epping 

 Forest, Essex (B.M. 1256) ; Dorset (B.M. 2323) ; Norfolk (B.M. 2324) ; 

 France (Paris Herb.) ; Germany (B.M. 413) ; Dorfhalden (B.M. 861) ; 

 Bohemia (B.M. 2326) ; Switzerland (B.M. 2325) ; Massachusetts 

 (B.M. 1258) ; Philadelphia (B.M. 1905) : var. obscurum — Devon 

 (B.M. 1257) ; Hungary (K. 1529) ; Adirondack Mountains (B.M. 1259) : 

 var. nitens — New Hampshire (B.M. 1260); Maine (B.M. 1261); Iowa 

 (B.M. 1011). 



57. P. alpinum G. Lister in Journ. Bot., xlviii. 73 

 (1910). Plasmodium ? Sporangia clustered or scattered, 

 sessile, 1 to 1-3 mm. diam., or forming curved or straight 



