46 THE NORTH AMERICAN SLIME-MOULDS 



1801. Physarum globuliferum Pers., Syn., p. 175, T. III., Figs. 10, n, 12. 



1829. Diderma globuliferum Fries, Syst. Myc., III., p. 100. 



1876. Physarum petersii farlowii Rost., Mon., App.* p. 6. 



1879. Physarum albicans Peck, Rep. N. Y. Mus., XXX.. p. 50. 



1893. Physarum columbinum Macbr., Bull. Lab. Nat. Hist. Iowa, II., 384. 



Sporangia gregarious, stipitate, globose, or slightly depressed, 

 above, pale blue gray or pure white ; stipe sometimes equal to 

 the sporangium, generally longer, slender, slightly wrinkled, 

 white or yellow, pallid, when longer tapering upward ; colu- 

 mella white, conical, sometimes obsolete ; hypothallus none ; 

 capillitium dense, but delicate, persistent, a close network of 

 hyaline threads, with white or yellowish nodes sparingly 

 thickened and calcareous, many without lime ; spore-mass 

 brown ; spores, by transmitted light, violet, minutely warted, 



7-5-9^- 



This species, very common eastward, rare west of the 

 Mississippi, is at once very beautiful and very variable. Its 

 several phases have been again and again observed and 

 described too often by distinct specific or varietal names. A 

 form from New York, with long, white stems and almost pure 

 white sporangia, is P. albicans Peck. From New England, 

 specimens sent to Rostafinski were by him regarded as a 

 variety of P. petersii B. and C., and called, I.e., P. petersii var. 

 farlowii Rost. By this name the species has been generally 

 distributed in this country. N. A. F., 1120. Most gatherings 

 of this form have small, somewhat ochraceous, sporangia, and 

 pale yellow or somewhat rusty stipes. These latter, with 

 somewhat heavier stem, represent Physarum simile Rost. A 

 form collected sparingly in Iowa has short, white stipes and 

 blue gray sporangia one-third larger than observed in the eastern 

 types. This was recorded, I.e., as P. columbinum Macbr. The 

 spores in the Iowa specimens are also a little larger, S-ro ft. 



In all phases the persistent tenacity of the capillitium is 

 a striking characteristic well noticed by Fries (I.e., p. 101): 

 " Peridia a gleba omnino libera, dein tota diffracta, evanescentia, 

 . . . capillitio compacto forma servata persistente." The perid- 



