The North American Slime-Moulds Part 51

PLATE XIX., Figs. 5 and 5 _a_.

1873. _Alwisia_ Berk. & Br., _Jour. Linn. Soc._, Vol. XIV., p. 86.

Sporangia ellipsoidal, cl.u.s.tered, stipitate; dehiscence by the falling away of the upper part of the peridium disclosing a persisting pencil of capillitial threads. A single species:--

1. ALWISIA BOMBARDA _Berk. & Br._

1873. _Alwisia bombarda_ Berk. & Br., _Jour. Linn. Soc._, XIV., p. 86.

Sporangia gathered in cl.u.s.ters of four to eight, surmounting coalescent, or sometimes divergent stalks, rusty-brown, or pallid, the peridium evanescent above; the coalescing stalks forming, especially below, a cl.u.s.tered column, 2 mm. in height, equalling the sporangia, dull reddish-brown in color; capillitium of rigid, tubular, generally simple threads, attaching above by delicate tips, below by a broader sometimes branching base, sometimes conjoined near the peridial wall, now and then at irregular intervals inflated slightly or anon bulbose, roughened by projecting spinules, one-third the diameter, brownish or yellow; spores reddish-brown, faintly marked by reticulating bands over large part of the surface, 5-5.5 .

This peculiar species looks at first very little like a myxomycete. The stiff projecting hairs of the capillitium are hyphal in appearance and under the lens recall the phycomycetes; but the spores and withal the general structure seem to claim recognition here. Rostafinski was inclined to make a trichia of it, because of the hair-like capillitium, and markings on the threads, Ma.s.see found indistinct spiral markings even, enough to suit at least the prototrichias. Mr. Lister would put it near the tubifers. Father Torrend thinks of the dianemas, margaritas, etc., because of simple capillitium attached above and below!

Spore-characters are probably the index most reliable, and the partial reticulation suggests a.s.sociation with _Tubifera_ and for the present it may find station there, as in the English monograph.

Rare. Collected three times: twice in Ceylon, once in Jamaica. By the courtesy of Dr. Farlow, late lamented, we record the western specimens.

_D._ RETICULARIACEae

Fructification aethalioid; the sporangia sometimes poorly defined, intricately a.s.sociated, borne on a common hypothallus and covered above by a common cortex; the lateral walls variously perforate and incomplete, form a pseudo-capillitium; spores umber or ochraceous.

=Key to the Genera of the Reticulariaceae=

_A._ Spores umber.

_a._ Sporangia wholly indeterminate, their walls much consolidated below, fraying out above into long, slender threads, 1. RETICULARIA

_b._ Sporangia bounded, more or less distinctly, by broad perforate plates throughout 2. ENTERIDIUM

_B._ Spores ochraceous 3. DICTYDIaeTHALIUM

=1. Reticularia= (_Bull._) _Rost._

1791. _Reticularia_ Bulliard, _Champ. de la France_, p. 95, in part.

1873. _Reticularia_ (Bulliard) Rost., _Versuch_, p. 6.

Plasmodium at first white, then pink, 'ashes of roses,' etc. Sporangia wholly indeterminate or undefined, their walls represented (?) by a spongy ma.s.s of so-called capillitium, consisting of membranous plates, branching, anastomosing, vanishing without order or symmetry, generally giving rise at the sides, and especially above, to long slender flexuous threads; outer cortex silvery white; hypothallus distinct, white; spore-ma.s.s and threads umber or rusty brown.

A single species,--

1. RETICULARIA LYCOPERDON (_Bull._) _Rost._

PLATE X., Figs. 7, 7 _a_; PLATE XII., Fig. 3.

1791. _Reticularia lycoperdon_ Bull., _Champ. de la France_, p. 95.

aethalium pulvinate, 2-8 cm. broad, at first silvery white, later less l.u.s.trous, the cortex irregularly and slowly deciduous; hypothallus at first conspicuous as a white margin extending round the entire aethalium, evanescent without, but persisting as a firm membrane beneath the spore-ma.s.s, pseudo-capillitium abundant, tending to form erect central ma.s.ses which persist long after the greater part of the fruit has been scattered by the winds; spore-ma.s.s umber, spores by transmitted light pale, reticulate over about two-thirds of the surface, the remainder slightly warted, 8-9 .

Not common. Often confused with the following, the spores of the two forms being very much alike; the internal structure, entirely different, and once compared, the two are thereafter easily distinguished at sight by external characters. The sporangial make-up is indifferent, confused.

It represents a phase in development whence might issue columellae with capillitium-branches or distinct tubular sporangia with persisting walls; or are such structures here but reminiscent only? Compare _Amaurochaete atra_, where similar conditions prevail. There differentiation goes on to the formation of a structure of which _Stemonitis_ is type; here the sporangium-wall becomes dominant; suffers modification for spore-disposal, an idea reaching fair expression in _Cribraria_ and _Dictydium_.

The plasmodium is white, noted Bulliard. Fries cites with approval the words of Schweinitz,--"color corticis ab initio argenteus sericeo nitore insignis; sed deinde sordescit e griseo in subfusc.u.m vergens."

Sometimes the surface does indeed shine as silver!

The fructification appears to be isolated in each case; the entire plasmodium consumed in a single plasmodiocarp.

Widely distributed. Maine to California, and south.

=2. Enteridium= _Ehrenberg_

1818. _Enteridium_ Ehrenberg, Link and Spreng., _Jahrb., Bd._ II., p. 55.

Fructification aethalioid; the confluent sporangia inextricably interwoven, the walls perforate by large openings, the resultant network of broad plates and bands widening at the points of intersection.

The genus _Enteridium_ is distinguished from _Reticularia_ chiefly by the more perfectly developed sporangial walls. These are everywhere membranous and do not show the abundant filiform dissipation so characteristic of _Reticularia_. The resultant structure in _Reticularia_ is a ma.s.s of more or less lengthened and anastomosing threads; in _Enteridium_, an exceedingly delicate but sufficiently persistent sponge. The "net-like, three-winged skeleton" referred to by Rostafinski results from the union at one point of three adjoining sporangia. Compare the section of the adjoining cells of a honeycomb.

Of this genus there are but two or three species, all so far occurring in our territory.

=Key to the Species of Enteridium=

_A._ Fructification umber brown 1. _E. splendens_

_B._ Fructification olivaceous 2. _E. olivaceum_

_C._ Fructification minute, 1-2 mm. 3. _E. minutum_

1. ENTERIDIUM SPLENDENS _Morg._

PLATE I., Figs. 1, 1 _a_, 1 _b_; PLATE XII., Figs. 4, 5.

1876. _Reticularia_ (?) _rozeanum_ Rost., _Mon. App._, p. 33.

1889. _Enteridium rozeanum_ (Rost.) Wing., _Proc. Phil. Acad._, p. 156.

1892. _Enteridium rozeanum_ Wingate, Macbr., _Bull. Lab. Nat. Hist.

Iowa_, II., p. 117.

1893. _Reticularia splendens_ Morg., _Jour. Cin. Soc._, p. 11.

1899. _Enteridium splendens_ Morg., Morg. _in litt._

aethalium pulvinate, even, or somewhat irregular, unevenly swollen or inflated, lobate or compound, covered by an exceedingly thin, generally smooth, shining, but never white, pellicle or cortex, brown, from 1-6 cm. in diameter; hypothallus white, often wide extending; capillitium none; the sporangial walls thin and brown forming a network as above described; spore-ma.s.s umber, spores by transmitted light pale, about two-thirds of the surface reticulate, the rest nearly smooth, 7-9 .

Very common, especially west, on decaying logs and stumps of every description. Easily distinguished by its brown color and smooth, shining, though uneven surface. The plasmodium as it emerges to form fruit is pale pink or flesh color, slowly deepening to brown as maturity advances. The first emergence is a watery white.

New England, Canada, to Minnesota and Nebraska, South Dakota.

In 1876 Rostafinski provisionally referred to the genus _Reticularia_ certain specimens received from M. Roze of Paris. Thirteen years later in correspondence with M. Roze, Mr. Wingate satisfied himself that the specimens discovered by Roze were the same as our common enteridium. He therefore, _l. c._, applied to our American forms the name they have widely borne, _E. rozeanum_. Mr. Lister, _Jour. of Botany_, Sept. '91, applied the Rostafinskian name to certain English specimens. Thereafter to be known as _Reticularia lobata_ Rost. and so fixed the status of that species. From all the literature before us it appears that Mr.