. 6.
1879. _Physarum albicans_ Peck, _Rep. N. Y. Mus._, XXX., p. 50.
1893. _Physarum columbinum_ Macbr., _Bull. Lab. Nat. Hist. Iowa_,
II., 384.
1899. _Physarum globuliferum_ (Bull.) Pers., Macbr., _N. A. S._,
p. 45.
1911. _Physarum globuliferum_ Pers., Lister, _Mycetozoa, 2nd ed._,
p. 48.

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; columella 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 mu.
Plasmodium greenish-yellow.

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. Forms occur like _P.
albicans_, but flushed with _rose_ throughout. From New England,
specimens sent Rostafinski were by him deemed a variety of _P. petersii_
Berk. & C., and called _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 species 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, _l. c._, as _P. columbinum_ Macbr.; name already in use. The
spores in the Iowa specimens are also a little larger, 8-10 mu. Pale
cyanic and roseate forms also sometimes occur in late fruitings; see
next species.

In all phases the persistent tenacity of the capillitium is a striking
characteristic well noticed by Fries (_l. c._, p. 101): "Peridia a gleba
omnimo libera, dein tota diffracta, evanescentia, ... capillitio
compacto forma servata persistente." The peridium, except a small part
below, all falls away, leaving the capillitium apparent