physarum] physaraceae 57 



In this abundant and variable species, the sporangium-wall as in 

 P. nutans is somewhat persistent when the lime is abimdant ; when this 

 is more scanty the wall soon breaks up in small fragments, remaining 

 attached to the capillitium. The colour of the sporangia found on the 

 same stump may differ from one year to another. The lime-knots are 

 very variable both in size and colour ; pale yellow sporangia have 

 often red-brown knots, and dark sporangia have light orange knots. 

 The stalks vary in tint in all forms. The specimen from Chili (leg. 

 Gay) in the Paris Museum, given by Rostafinski (Mon., App. p. 7) 

 as a type of Physarum Leveillei var. chrysopus, is the orange form of 

 P. viride ; the stalks are free from lime deposits and the capillitium con- 

 sists of slender threads with fusiform orange lime-knots. The var. 

 rigidum has marked characteristics, but is connected with typical 

 P. viride by intermediate forms. The lenticular sporangia are either 

 convex, flat, or umbilicate above, and are often somewhat iridescent 

 from having little lime in their fragile walls ; the stalks vary in colour 

 as in other forms of P. viride ; the capillitium consists in some gatherings 

 of rather few simple or forked threads and flattened tubes, with scanty 

 lime deposits, while in other gatherings it is composed of straight rod- 

 like tubes densely charged with lime-granules, and attached to the 

 sporangium-walls above and below either directly or by short hyaline 

 threads ; the spores are usually larger and rather darker than in typical 

 P. viride. This variety has now been obtained from the West Indies, 

 from Ceylon, and several times from Japan. 



Hob. On dead wood. — Leytonstone, Essex (B.M. 1219) ; Bath- 

 easton, Gloucestershire (B.M. 90) ; Yorks (B.M. 1046) ; France (Paris 

 Herb.); Germany (B.M. 506); Norway (B.M. 1220); Portugal 

 (B.M. 2132); Ceylon (K. 1420); Borneo (B.M. 1221); Japan (B.M. 

 1989) ; Bonin Islands (K. 335) ; Iowa (B.M. 805) ; New Jersey 

 (B.M. 1223) ; Chili (Paris Herb.). 



19. P. Bethelii Macbr. in litt. Plasmodium ? Sporangia 

 stalked, subglobose umbilicate beneath, erect or in- 

 clined, - 5 to 0-7 mm. diam., pale sulphur-yellow, or when 

 free from lime iridescent-violet ; sporangium-wall mem- 

 branous with more or less abundant deposits of sulphur- 

 yellow lime-granules. Stalk firm, dark brown or black, 

 containing dark refuse matter, 0-1 to 05 mm. high. Colu- 

 mella none. Capillitium a dense network of delicate hyaline 

 threads with irregular and often branching pale yellow lime- 

 knots. Spores vioiet-brown, minutely warted, 9 to 10^ diam. 



PI. 200. — a. iridescent sporangia (Colorado, from type specimen) ; b. capillitium 

 and spores ; c. spore ; d. sporangia with abundant lime (Cheyenne Mountain, Colorado). 



This species appears to be closely allied to P. viride var. incanum, 

 from which it is distinguished by the stouter habit, the branching and 

 larger lime-knots, and by the darker spores. It has been found twice, 

 each time in Colorado, once by Mr. E. Bethel, once by Dr. Sturgis. 

 The sporangia gathered by Dr. Sturgis vary from sulphur-yellow to 

 iridescent- violet according to the lime in the walls being abundant or 

 absent ; those gathered by Mr. Bethel are iridescent-violet, but some 

 show scanty pale yellow lime-deposits on the walls ; the capillitium and 

 spores are similar in both specimens. 



Hob. On dead wood.— Colorado (B.M. 2133, 2134). 



