52 Mycetozoa of North America 



in various parts of the world. A collection made by Dr. E. Bethel 

 in Colorado seems to be the form, althou^rh little but bases are left. 

 A gathering by Dr. R. Thaxter, in Chile in 1906, is representative, 

 and the spores measure 10-12 fx diam. Collections made by Prof. 

 C. Torrend in Portugal, have sporangia much smaller than those 

 of the Chile collection but the spores have the same size. A col- 

 lection made by Gardner, in 1903, in California, is like the Portu- 

 guese specimens. Massee gave the spore size as 6-7 /x, perhaps 

 an error, 



28. Physarum nucleatum Rex, Proc. Acad. Nat. So. Phila. 1891: 

 389. 1891. (N. Y. B. G. no. 6441, type material.) 



Plasmodium milk-white (Lister). Total height 1 to 2 mm. 

 Sporangia gregarious, rarely clustered, globose, about 0.5 mm. 

 diam., stalked, erect or inclined, white, rarely iridescent from 

 absence of lime; sporangial wall membranous, with scattered in- 

 cluded clusters of white lime-granules. Stalk subulate or nearly 

 cylindrical, 0.5 to 1.5 mm. long, wrinkled, pale buff or yellow, 

 rarely reddish yellow or streaked with red, translucent above, 

 without lime, and enclosing refuse matter at the base. Capilli- 

 tium a close, persistent network of very slender, colorless threads 

 with minute, scattered, rounded, white lime-knots; in the center 

 of the capillitium is usually a white, calcareous ball, 0.1 to 0.15 

 mm. diam., sometimes replaced by a cluster of irregular lime- 

 knots, occasionally absent entirely. Spores pale brownish lilac, 

 minutely spinulose, 6-7 m diam. 



Type locality: Philadelphia, Pennsylvania. 



Habitat: On dead wood and leaves. 



Distribution: Florida, Indiana, *Iowa, *Maryland, New 

 York, *Nicaragua, Ohio, *Oregon, Pennsylvania, Tennessee, Vir- 

 ginia, *Wisconsin. 



Illustration: Lister, Mycetozoa ed. 3. pi. 35. 



This species forms small colonies. It resembles P. glohidife- 

 rum, but may be distinguished by the semi-translucent stalk, and 

 the absence of a columella. Usually, but not always, the central 

 ball of lime is present. Var. rohustum G. Lister (Jour. Bot. 64: 

 226. 1926) is somewhat intermediate with P. psittacinum. It 

 has not been reported from North America. 



