The North American Slime-Moulds Part 48

1875. _Lamproderma arcyrionema_ Rost., _Mon._, p. 208.

Sporangia gregarious, scattered, globose, silvery gray or bronze, iridescent, erect, stipitate; stipe black, long, two-thirds to three-fourths the total height, slender, rigid; columella slender, cylindric, attaining about one-third the height of the sporangium when it breaks into the primary branches of the capillitium; capillitium exceedingly intricate, made up of slender, flexuous brown threads which frequently branch and anastomose to form an elegant round-meshed network resembling that of _Arcyria_, free ultimate branchlets not numerous; spores in ma.s.s jet-black, by transmitted light violaceous, smooth, or only faintly warted, 6-8 .

In outward appearance this species resembles _L. physaroides_, but is easily recognizable by its very peculiar capillitium. This, in its primary branching, resembles a comatricha. In typical forms, the columella branches at the apex only, generally into two strong divisions which then break up irregularly and anastomose in every direction. This seems to have been the form present to Rostafinski when he wrote "columella truncate." In Central American and some North American specimens, the branching is very different; the twigs leave the columella at various points almost down to the annulus, and the entire effect is dendroid. The columella is lost almost at once. A small form of this species was formerly distributed in the United States as _Comatricha friesiana_ DeBy. This circ.u.mstance led the present author to describe Central American forms as _C. s.h.i.+mekiana_. Judging from a remark by Ma.s.see (_Mon._, p. 97), a similar confusion seems to have prevailed in Europe. As a matter of fact, the resemblance between _C.

friesiana_, i. e. _C. nigra_, and the present species is sufficiently remote.

_Lamproderma minutum_ Rostafinski seems to be a small form of this species. Rostafinski bases his diagnosis upon the branching of the columella, which is, as we have seen, inconstant, and upon the colorless capillitium. This feature in specimens examined is also inconstant.

Occurring in large colonies on barkless decaying logs of various species; the plasmodium almost colorless.

New England, Pennsylvania, Ohio, Louisiana, Texas, Mexico, Nicaragua; Vancouver's Island; Ontario, Toronto,--_Miss Currie._

=4. Echinostelium= _DeBary_

1873. _Echinostelium_ DeBary, Rost., _Versuch_, p. 7.

Sporangia distinct, globose, minute, the structure limited to a few imperfect rib-like, loosely joined branches developed from the short columella or stem-top, sustaining the spores.

A single species:--

1. ECHINOSTELIUM MINUTUM _DeBy_.

1873. _Echinostelium minutum_ DeBy., Rost., _Versuch_, p. 7.

PLATE XIX., Figs. 11 and 11 _a_

Sporangia distinct, scattered, globose, very minute, 40-50 , stipitate; the stipe, hair-like subulate, granular but hyaline; columella minute or none; capillitium consisting of a few arcuate spinose threads loosely united supporting the uncovered spores, spores globose, colorless, smooth, 7-8 .--_Rostafinski._

This very singular and diminutive form, the least of all slime-moulds, is probably widely distributed but the accident of discovery is rare.

DeBary found it once only, at Frankfurt am Main.

Miss Lister reports its occurrence in England and Austria. In the United States it has been seen but once on certain laboratory material from Ma.s.sachusetts, studied by Dr. Thaxter.

Our drawing is after Rostafinski, IV., 68; Miss Lister follows No. 54, and so finds a bit of peridium below the two spores shown in the figure, one on each side of a microscopic _columella_.

This is almost the only taxonomic suggestion;--a mere suggestion; this microscopic bit of anxious life is but a shadow,--a shade, a shadow of a lamproderma!

ORDER III

CRIBRARIALES

Fructification plasmodiocarpous or aethalioid, or consisting of distinct sporangia; peridia membranaceous at maturity, more or less evanescent, opening irregularly or by means of a delicate network, which involves at least the upper part of the sporangium; capillitium usually none; spores of some shade of brown, umbrine, rarely purplish.

This order is distinguished--except in a single case--by the entire absence of true capillitium, the pallid or brown spores, the gradual evolution of distinct sporangia in which provision for spore-dispersal is made by peridial modification especially at the sporangium-top.

=Key to the Families of the Cribrariales=

_A._ Fructification plasmodiocarpous scattered as if made up of the segments of the plasmodial net LICEACae

_B._ Fructification of distinct and separate sporangia, long stipitate, opening by a delicate operculum at the top ORCADELLACEae

_C._ Fructification aethalioid, the sporangia generally more or less tubular, often prismatic by mutual pressure; opening by rupture of the apex, the lateral walls entire TUBIFERACEae

_D._ Fructification aethalioid, the sporangia ill defined, their walls more or less perforate, frayed, or dissipated, forming a pseudo-capillitium, RETICULARIACEae

_E._ Fructification of distinct and separate sporangia, the walls more or less reticulately perforate especially above CRIBRARIACEae

_A._ LICEACEae

A single genus,--

=1. Licea= (_Schrader_) _Rost._

1797. _Licea_ Schrader, _Nov. Gen. Plant._, p. 16, in part.

1875. _Licea_ (Schrader) Rost., _Mon._, p. 218.

Sporangia plasmodiocarpous, looped, irregular, or distinct, sessile, and regularly rounded or elliptical; the peridium simple, rather firm, ruptured irregularly or by simple fissure; hypothallus none.

This genus is distinguished from other similar plasmodiocarpous forms by the extreme simplicity of its structure. There is absolutely no capillitium nor anything like it, simply a ma.s.s of spores surrounded by thin membranous walls. The spores range from pale olive, colorless under the lens, through various shades of brown to dusky almost black in _L.

pusilla_. Schrader included the _Tubifera_ species.

=Key to the Species of Licea=

_A._ Plainly plasmodiocarpous 1. _L. variabilis_

_B._ Opening by regular segments.

1. Segments two only 2. _L. biforis_

2. Segments several.

i. Spores brown 3. _L. minima_

ii. Spores dusky olive 4. _L. pusilla_

1. LICEA VARIABILIS _Schrader._

PLATE XII., Figs. 7 and 8.

1797. _Licea variabilis_ Schrader, _Nov. Gen._, p. 18, Pl. VI., Figs. 5 and 6.

1801. _Licea variabilis_ Schr., Pers., _Syn. Meth._, p. 197.