physarum] physaraceae 45 



Sporangia pale yellow ; spores pale, nearly smooth, 

 8-10 /x. 51. P. conglomeratum 



b. Lime-knots yellow, red, or brown — 



Slender plasmodiocarps and large branching lime- 

 knots yellow. 52. P. Serpula 



Plasmodiocarps and lime-knots brown. 53. P. aeneum 



Sporangia red or brownish buff ; lime-knots large, 

 angular, orange-red or red-brown. 



54. P. rubiginosum 



Sporangia red ; linie-knots rounded, yellow, usually 

 with red centres. 55. P. lateritium 



Sporangia yellow or orange with single walls ; lime- 

 knots angular, yellow. 56. P. virescens 



Plasmodiocarps stout, yellow or buff, with double 

 walls ; lime-knots large, yellow, angular. 



57. P. alpinum 



1. P. leucopus Link in Mag. Ges. Nat. Fr. Berl., iii. 27 

 (1809). Plasmodium opaque- white. Total height about 1 mm. 

 Sporangia globose, greyish- white or glaucous, 0*5 mm. diam., 

 gregarious or clustered, stalked, rarely almost sessile ; 

 sporangium-wall delicately membranous, containing scattered 

 or clustered white globular lime-granules. Stalk white, 

 stout, 0-15 to 02 mm. thick, with a few shallow longitudinal 

 furrows, erect, rigid, brittle, somewhat narrowing upwards, 

 chalk-white in section to the base, rising from a more or less 

 developed white hypothallus, enclosing no refuse matter. 

 Columella none. Capillitium consisting of delicate branching 

 hyaline threads connecting large irregular white lime- 

 knots, which are 10 to 50 /x broad and filled with globular 

 lime-granules 1 to 1-5 /x diam. Spores violet-brown, minutely 

 spinulose, 7 to 10 /x diam. — Rost. Mon., p. 101 ; Mass. Mon., 

 287, in part ; Macbr. N. Am. Slime-Moulds, 48. P. 

 bullatum Link I.e. ; Ditm. in Sturm Deutsch. Fl., Pilze, 

 45, t. 22. Didymium leucopus Fr. Syst. Myc, iii. 121 (1829). 



PL 15. — a. sporangia; b. capillitium with fragment of sporangium-wall and spores 

 ■c. spore ; (England). 



The snow-white stalk, which is chalk-white in section to the base, 

 distinguishes P. leucopus from P. nutans, where the stalk almost 

 always contains dark refuse matter, while the lax capillitium, 

 with large lime-knots and the large lime-granules in the knots and 

 sporangium-wall, separate it from P. globuliferum. Sporangia some- 

 times occur having more slender buff or pale brown stalks in company 

 with others having the usual white stalks. 



Hab. On dead leaves, moss, etc. — Batheaston, Somerset (B.M. 48) ; 

 Lyme Regis, Dorset (B.M. 1196) ; France (B.M. 3185) ; Sweden (B.M. 

 2088); Germany (B.M. 2089); Portugal (B.M. 2090); Java (B.M. 2091); 

 Ohio (B.M. 1198); New Granada (Paris Herb. ). 



