physarum] physaraceae 65 



or lenticular, stalked, erect or somewhat inclined, scattered, 

 0*4 to 0*6 mm. diam., white with a reddish base, rugose ; 

 sporangium- wall membranous, colourless above, with dense 

 clusters of included white granules, thickened and rufous at 

 the base. Stalk subulate or cylindrical, furrowed, 05 to 1-5 mm. 

 long, red-brown, free from refuse matter. Columella none. 

 Capillitium a network of colourless branching threads with 

 lime-knots often varying in the same development ; they 

 are either small and few, or large branching and numerous, or 

 approaching the type of Badhamia. Spores pale brownish- 

 violet, almost smooth, 8 to 11//. diam. — Didymium pusillum 

 Berk. & Curt, in Grev., ii. 53 (1873). Physarum nodulosum 

 Cooke & Balf., Rav. N. Amer. Fung., no. 479 (1881) (undes- 

 cribed) ; Macbr. N. Am. Slime-Moulds, 51 (1899). P. calidris 

 Lister in Journ. Bot., xxix. 258 (1891) ; Lister Mycetozoa, 52. 

 P. gravidum Morg. Myx. Miami Valley, 96 (1896). Badhamia 

 nodulosa Mass. in Journ. Myc, v. 186 (1889) ; Mass. Mon., 

 322. Craterium nodulosum Morg. I.e., 15. 



PI. 43. — a. sporangia (Bedfordshire) ; b. capillitium and spores of the same ; c. 

 sporangia of stouter form (Wanstead, Essex) ; d. capillitium and spores of the same ; 

 «. spore. 



P. pusillum in its various forms, shows amongst the species of 

 Physarum, with white lime-granules a striking resemblance to the group 

 P. flavicomum, P. Maydis and P. auriscalpium amongst the species with 

 yellow lime-granules, while the short-stalked form of P. pusillum 

 with Badhamia-like capillitium merges into Badhamia panicea as P. 

 auriscalpium merges into Badhamia decipiens. The specimen from 

 South Carolina in the Kew Herbarium, K. 1492, contains the type of 

 this species. It consists of two specimens on two slips of wood marked 

 " Didymium pusillum.'''' On one slip is the present species, described 

 by Berkeley under this name in Grev. I.e. On the other are a few 

 sporangia of D. nigripes var. xanthopus ; these exactly resemble the 

 type of D. proximum Berk. ( — D. nigripes Fr. var. xanthopus), also 

 from South Carolina. Confusion has arisen owing to this inadvertent 

 combination of two species, with the result that Rostafinski gives 

 D. pusillum as a synonym for D. proximum (Rost. Mon., App. p. 23), 

 only noticing the characters of the latter. The specimen from Broome's 

 Herb, named P. elephantinum Berk. &Br. in MS., from Ceylon(B.M. 453), 

 is a large form of the present species, with capillitium and spores similar 

 to those in the English gatherings. P. nodulosum Cooke & Balf. 

 (B.M. 858) from South Carolina is also P. pusillum, but has almost 

 Badhamia-like capillitium. 



Hab. On dead leaves, twigs, straw, etc. ; frequent. — Lyme Regis 

 (B.M. 1237) ; Bedfordshire (B.M. 1703) ; Northants (K. 1549) ; Linlith- 

 gow (K. 1504) ; Montpellier (B.M. 2168) ; Parma (B.M. 496) ; Portugal 

 (B.M. 2173); Switzerland (Herb. Zurich); Germany (B.M. 2169); 

 Nielgherries (K. 1531) ; Ceylon (B.M. 453) ; Java (B.M. 2170) ; New 

 Zealand (B.M. 2171) ; Japan (B.M. 2172) ; South Carolina (B.M. 858) ; 

 Antigua (B.M. 1650) ; Bolivia (B.M. 2174). 



33. P. didermoides Rost. Mon., p. 97, fig. 87 (1875). 

 Plasmodium white. Total height 05 to 1*3 mm. Sporangia 



