68 ENDOSPOREAE [PHYSARUM 



stalks stouter, rarely containing lime ; columella occasionally 

 present as an irregular or conical continuation of the stalk into 

 the sporangium ; capillitium usually more rigid than in the 

 type, with broad expansions at the axils and large, often 

 branching lime-knots that are sometimes confluent in 

 the centre of the sporangium ; spores 9 to 11 p. — Physarum 

 leucophaeum Fr. Symb. Gast., 24 (1818) ; Rost. Mon., p. 113, 

 figs. 77, 78, 89 ; Mass. Mon., 288 ; Macbr. N. Am. Slime-Moulds, 

 44. P. confluens Link in Mag. Ges. Nat. Fr. Berl., vii. 43 

 (1815) ? P. hypnorum Link I.e., 43 ? P. connexum Link I.e., 

 iii. 28 (1809)? P. conglobatum Ditm. in Sturm Deutsch. Fl., 

 Pilze. 81, t. 40 (1817). P. albipes de Bary in Zeitschr. Wiss. 

 Zool.,x. 95 (1860). P.granulatum Balf. in Grev., x. 115 (1882); 

 Mass. I.e., 289. P. imitans Racib. in Rozpr., Mat.-Przyr. 

 Acad. Krak., xii. 73 (1884). P. Readeri Mass. I.e., 282. 

 Sphaerocarpus albus Bull. Champ., 137, t. 470 h to l 

 (1791). Trichia filameniosa Trentep. in Roth Catal. Bot., 

 i. 227 (1797). Tilmadoche nephroidea Cel. fil. Myx. Bohm., 



69 (1893). 



PI. 37. — a. sporangia (Essex) ; b. capillitium and spores ; e. spore : d. d. 1 sporangia 

 intermediate between the typical form and sub-species leucophaeum (Essex) ; e. capilli- 

 tium of d., with abundant lime-knots ; /. capillitium of d.' with few small lime-knots. 



PI. 38. — a. sporangia of subsp. leueophaeum (Essex) ; b. capillitium and spores of the 

 same ; c. robust sporangia, with much lime in the walls ; d. capillitium and spores 

 of c ; e. spore. 



An extremely variable and abundant species. The stalked and 

 plasrnodiocarp forms may develop from the same growth of Plas- 

 modium ; sporangia may be found with delicate capillitium and few 

 minute lime-knots, associated with others from the same plasmodium 

 with wide expansions at the angles of the threads and with large lime- 

 knots ; some may have erect stalks enclosing much refuse, standing with 

 others more weakly formed, containing little refuse matter and cernuous 

 from the weight of the sporangium. As in all the Calcarineae the amount 

 of lime in the sporangium-wall is liable to great variation ; where the 

 supply is abundant it gives firmness and persistence to the membrane ; 

 where it is scanty the wall is fragile or evanescent, as in the form named 

 by Rostafinski Tilmadoche nutans. In contrast with the latter, a robust 

 form occurs, having a short stout stalk, often projecting within the 

 sporangium in a conical point, with lime-knots of large size, either 

 distributed among the capillitium or confluent in the centre ; between 

 these extreme forms all shades of "difference may be found, making it 

 difficult to define even distinct varieties. Examination of a large series 

 leads to the conclusion that P. leucophaeum is not a distinct species, 

 but must be included under P. nutans. The specimen of T. gracilenta 

 Rost. from Poland in the Strassburg collection is a minute form of 

 P. nutans with small, nearly globose sporangia of a greyish-white or 

 greyish-violet colour, as described in Rostafinski's monograph, and not 

 " fusco-atra " as given in Sacc. Syll., vii. p. 360. The type of Physarum 

 Readeri Mass., from Melbourne (K. 500), is the subsp. leucophaeum, 

 with spores 8 to 9 p. diam. (not 15 to 16 p). The type of P. granulatum 

 Balf. fil. (K. 67) is the same subspecies with the lime of the sporangium - 

 wall in sand-like granules, a not infrequent modification in species of 



