PHY S A RUM 73 



brown ; spores by transmitted light, violet-brown, delicately warted, 

 7-8 /x. 



This species is well marked by several characteristics; the brilliant 

 wall of the peridium, white-flecked and laciniate, the delicate Didym- 

 ium-\\\it capillitium running from centre to peridium, and especially 

 the peculiar aggregation of lime at the center of the sporangium, 

 like nothing else except a similar structure found in Physarum 

 nucleatum Rex. The variations afifect the stipe and the distribution 

 of the capillitial lime. Some eastern specimens show stipes melano- 

 podous, black below; specimens from Ohio and Nicaragua show 

 stipes milk-white throughout. As to the capillitium, in some of the 

 Nicaragua collections the lime is more uniformly distributed through 

 the capillitium, and accordingly the nucleus is not conspicuous, its 

 place being taken by two or three nodes plainly larger than the 

 others. The peculiar brown metallic lustre of the peridial wall, and 

 the strongly developed calcareous patches with which the peridium is 

 covered are constant features. 



That this is the Didymium columbinum Berk., or T. columbina 

 (Berk.) Rost., is very doubtful; the specific name given by Wingate 

 becomes inapplicable when the series is transferred to Physarum, 

 since in that genus the combination is already a synonym. See P. 

 compactutn Ehrenberg, Syl. Myc. Bed., p. 21 (1818), cited repeat- 

 edly in the synonymy; Fries, op. ctt.. Vol. III., p. 101. So also P. 

 columbinum, I. c, pp. 133, 135, etc., to say nothing of the fate of 

 Persoon's first record, Obs. Mycol. pars prim., p. 5, 1796 This is 

 Wingate's species, let it bear his name. 



30. Physarum newtoni Macbr. 



Plate XIV., Figs. 5, 5 a, 5 b. 



1893. Physarum neivtoni Macbr., Bull. Lab. Nat. Hist. Io<wa, II., p. 390. 



1899. Physarum neivtoni Macbr., A'^. A. S., p. 37. 



1911. Physarum neivtoni Macbr., Lister, Mycetozoa, 2nd ed., p. 54. 



Sporangia simple, gregarious, short-stipitate or sessile, globulose or 

 flattened, when not globose, depressed and deeply umbilicate above, 

 purple, smooth, thin-walled, stipe when present very short and con- 

 colorous; columella none; hypothallus none; capillitium abundant, 



