physarum] physaraceae 53 



PI. 26. — a. sporangia ; b. apex of stalk and capillitium, with fragment of sporangium - 

 wall, showing sharply defined clusters of lime-granules ; c capillitium and spores ; 

 d. spore ; (Dominica). 



An excellent account of this species is given by Mr. Wingate (I.e.). 

 He describes the sporangium-wall as splitting on maturity in a 

 floriform manner, which is a marked character in many specimens ; 

 his description of the stalk as " yellowish-white with a brown or 

 blackish base " appears to be correct for the American gatherings. 

 In a fine specimen of P. compactnm in the Kew collection from 

 Dominica, K. 567 (type of Lepidoderma stellatum Mass.) the stalks 

 are pure white with a chalky section to the base. A specimen from 

 French Guiana in the Paris Museum, under the name Physarum 

 leucophaeum, is precisely similar in all respects to the Dominica gathering 

 of P. compactnm. The type of Didymium columbinam Berk. & Curt. 

 (Tilmadoche columbina Host. Mon., App. p. 13), Venezuela (K. 1428), 

 may be this species, but nothing now remains of the specimen 

 but a few stalks and a little of the extremely delicate capillitium. 

 D. Barteri Mass. (type in Herb. Massee) collected by Barter on Prince's 

 Island, Niger Expedition, in 1881, is clearly P. compactnm ; the specimen 

 is quoted under P. globidiferum by Rostafinski (Mon., App. p. 5). 



Hob. On dead wood.— Java (B.M. 2117); Borneo (B.M. slide); 

 Dominica (K. 567) ; Philadelphia (B.M. 875) ; Ohio (B.M. 1214) ; 

 Kansas (B.M. 2118); South Carolina (B.M. 571); Antigua (B.M. 

 1647) ; Brazil (B.M. 2119). 



13. P. mutabile Lister. Plasmodium ? Sporangia cylin- 

 drical, ovoid, or subglobose, 0*3 to 0-6 mm. diam., white, 

 rugulose, either stalked or sessile, often forming elongated 

 branched plasmodiocarps ; sporangium-wall with rather evenly 

 distributed deposits of white lime-granules. Stalks stout or 

 slender, 0-1 to 0*4 mm. high, ochraceous-yellow, usually en- 

 closing white lime granules but sometimes almost free from 

 lime, often connected at the base by a yellowish or white 

 hypothallus. Capillitium a persistent network of firm hyaline 

 threads with expansions at the axils ; lime-ki40ts white, 

 varying in size and shape, either scattered through the cajulli- 

 tium, or in the stalked forms for the most part confluent in 

 the centre of the sporangium and forming a clavate columella 

 which is either free or continuous with the apex of the stalk- 

 Spores purple-brown, sjnnulose, 7 to 8 /x diam. — Crateriachea 

 mutabilis Rost. Mon., p. 126 (1875) ; Mass. Mon., 344. 

 Physarum cinereum Lister Mycetozoa. 56 (1894), in part. 

 P. Crateriachea Lister in Joum. Bot., xxxiii. 323 (1895). 



PI. 44. — a. sporangia (from near Luton, Beds); b. capillitium and spores; c. spore. 



A widely distributed and variable species. In this country it is 

 sometimes found in great abundance on heaps of old straw, dead leaves 

 or herbaceous stems ; stalked, sessile or plasmodiocarp forms occur 

 side by side, while the lime-knots show every stage from being quite free 

 to uniting to form a well-defined clavate or cylindrical columella. The 

 specimens distributed by Cesati as " Didymium neapolitanum," from 

 Naples (B.M. 573), and also those marked Didymium squamulosum var. 

 herbarum by Rabenhorst & Winter, no. 2969, from Pavia (B.M. 542), 



D 



