Link simply translated the name into Greek, for reasons less evident now, and in this was followed by Fries. Haller's designation is now probably securely fixed.

The sporigerous median structure of the fructifications, under whatever specific name or names, is entirely confused. Sporangial walls, if ever such there were, are hardly as such recoverable, seemingly _indicated_ only, in the changes to which the aethalium submits as in the ripening the sporogenic plasm pa.s.ses on to spores.

In the present state of our knowledge the forms of this genus present withal a most perplexing problem. Are they simply phases of a single species, or are they in style and in structure sufficiently constant in their admitted variety, to claim specific rank and separate description?

To follow the example of Greville and recognize in all the literature of two hundred years varied descriptions of a single type,--this were perhaps the easier and speedier disposal of the case. Fries thought so to treat the problem but was unable to keep faith with his own decision; for no sooner he states the genus monotypic than he proceeds forthwith to offer four varieties, a. b. c. d., viz. those by Persoon and others duly recognized as species.

Recent students all, however, seem to find convenience in specific division. All seem disposed to honor Dr. Peck's _Fuligo ochracea_ whether or not by the name he gave; and of other varieties some seem impressed by the constancy of one, some of another characteristic, thus indicating that to careful observers all over the world there are differences that may be recognized, that have been recognized again and again. If there are two species there are certainly more. Out of the gatherings of many years one may set in order not less than five variations in the fruiting of _Fuligo_, five distinct types of fructification, to all appearing sufficiently constant for specific recognition.

It will be said, has been said, was said by Fries, that these variations are insignificant, "pendent ex aeris const.i.tutione"; but as a matter of fact the several types now in question may be found on the same day, so that evidently something other than the atmospheric environment must determine.

Again it is said that the differences are in external form or color only, the spores in all cases almost if not quite the same. This is true; but specific characters are _surface_ characters in fact: a species morphologically is merely the form in which a _kind_ or _genus_ presents itself. If the presentation be constant, for our convenience we say so, in bestowing a name. Whether in our present treatment the convenience is purely personal, students may decide.

However it all may be, there are in this part of the world many varying presentations of _Fuligo_ capable of ill.u.s.tration and description; the same forms, perhaps, which have attracted the notice of the more acute mycologists in the older history of the subject. Some of these forms we here venture to describe, with such annotation as may show something of present knowledge.

=Key to the Species of Fuligo=

_A._ aethalium 1 cm. or less; spores spherical 1. _F. muscorum_

_B._ aethalium larger, or plasmodiocarpous, even sporangi-form, crust white, smooth, even, spores elliptical 2. _F. cinerea_

_C._ aethalia larger, 2 cm. or more.

1. Cortex yellow, etc., not white; spores 6-8 3. _F. septica_

2. Cortex nearly or quite wanting; spores 10-12 4. _F. intermedia_

3. Cortex white, a foamy crust; spores 15-25 5. _F. megaspora_

1. FULIGO MUSCORUM _Alb. & Schw._

1894. _Fuligo muscorum_, Alb. & Schw. Lister, _Mycetozoa_, p. 67.

1875. _Licea ochracea_ Peck, N. Y. _Rep._, XVIII., p. 55.

1879. _Fuligo ochracea_ Peck, N. Y. _Rep._, x.x.xI., p. 56.

1894. _Fuligo muscorum_, Alb. & Schw., Lister, _Mycetozoa_, p. 67.

1911. _Fuligo muscorum_ Alb. & Schw., Lister, _Mycetozoa, 2nd ed._, p. 87.

Plasmodium orange-yellow. aethalium globoid, very small, 1 cm. or less, the cortex very thin, greenish yellow; sporangial walls not evident; capillitium well-developed, the numerous calcareous nodes fusiform or often branching, and connected by rather short, transparent internodes; spores coa.r.s.ely warted, 10-11 .

This form seems to differ from _F. septica_ chiefly in its constant diminutive habit of fruiting, in its delicate cortex, and in its spores, brighter, larger, and more coa.r.s.ely warted. The descriptions and figure by Schweinitz seem referable to nothing else. First reported by Albertini and Schweinitz from Germany; by Schweinitz from the Carolinas; then by Dr. Peck described as a _Licea_ from New York. It seems less commonly collected in the United States.

2. FULIGO CINEREA (_Schw._) _Morg._

PLATE X., Figs. 3, 3 _a_, and 3 _b_, and Plate XXIII.

1831. _Enteridium cinereum_ Schw., _N. A. F._, No. 2365.

1875. _Physarum ellipsosporum_ Rost., _Mon. App._, p. 10.

1884. _aethaliopsis stercoriformis_ Zopf., _Pilzthiere_, p. 150.

1894. _Fuligo ellipsospora_ Lister, _Mycetozoa_, p. 67.

1896. _Fuligo cinerea_ (Schw.) Morg., _Cin. Soc. Nat. Hist._, p. 105.

1899. _Physarum ellipsosporum_ Rost., Macbr. _N. A. S._, p. 27.

1911. _Fuligo cinerea_ Morg., List., _Mycetozoa_, 2nd ed., p. 88.

Plasmodium milk-white, watery. Plasmodiocarp long and widely effused, anon winding, here and there reticulate, always applanate; sometimes in form an aethalium, the peridial cortex membranous, firm, thick, and white. Capillitium well-developed, furnished with lime. Spores thin-walled, ellipsoidal, violaceous, plicate-rugose, 14-16 x 11-12 .

Not common. Found occasionally in shaded situations on piles of rotting straw or in the woods, especially on detritus of the bracken. The spores are many of them ellipsoidal; some are spherical; all are decidedly spinulose, perhaps might appear plicate-rugulose when dry or shrunken.

Calcareous nodules very large and irregular, white.

Schweinitz, _loc. cit._, described this form as _Enteridium cinereum_.

Rostafinski referred it to the genus _Physarum_, but was obliged to adopt also a new specific name, as that suggested by Schweinitz was already in use in the genus _Physarum_. Zopf, _Die Pilzthiere_, p. 149, founds a new genus on what seems to be the same form as here considered.

This he publishes as _aethaliopsis stercoriformis_ Z. Ma.s.see regards the specimens discovered by Zopf as belonging to the genus _Fuligo_, and Lister regards Rostafinski's type as _Fuligo_, and includes Zopf's material under the Rostafinskian species.

This has been described as properly an American form; Lister cites other far localities.

3. FULIGO SEPTICA (_Linn._) _Gmel_.

1753. _Mucor septicus_ Linn., _Sp. Pl._ II., No. 1656 (?).

1763. _Mucor ovatus_ Schaeff., _Fung. Bav._, p. 132, Fig. 192.

1791. _Fuligo septica_ (Linn.) Gmel., _Syst. Nat._, p. 1466.

1826. _Fuligo varians_ Sommf., _Fl. Lapl. Sup._, p. 231.

1809. _aethalium flavum_ Link, _Diss._, I., p. 42.

1829. _aethalium septic.u.m_ Fr., _Syst. Myc._, III., p. 93.

1875. _Fuligo varians_ Sommf., Rost., _Mon._, p. 134.

1892. _Fuligo varians_ Sommf., Macbr., _Bull. Lab. Nat. Hist. Ia._ II., p. 160.

1894. _Fuligo septica_ (Linn.) Lister, _Mycetozoa_, p. 66.

1899. _Fuligo ovata_ (Schaeff.) Macbr., _N. A. S._, p. 23.

1911. _Fuligo septica_ Gmel., Lister, _Mycetozoa, 2nd ed._, p. 86.

This remarkable and universal species presents as stated many forms and phases. Of these five have been selected as representative.

1. Form _a._ Plasmodium yellow; cortex yellow, or orange-brown, strongly calcareous friable; form indefinite _F. ovata_

2. Form _b._ Cortex less calcareous porose, yellowish brown, fructification definite, pulvinate _F. rufa_

3. Form _c._ Cortex smooth, persistent; fructification small, less than two inches _F. laevis_

4. Form _d._ Plasmodium yellow; cortex none; capillitium yellow, fructification thin, sometimes wide-spread _F. flava_

5. Form _e._ Plasmodium violaceous, dark; cortex almost none; whole ma.s.s reddish or violet _F. violacea_

1. Form _a._ _Fuligo ovata_ (Schaeff.) Pers.

Plasmodium bright yellow; aethalium pale brown, or yellowish-ochraceous, of variable size and shape, one to many cm. in diameter, and one to two cm. thick, enclosed by a distinct calcareous crust, which varies in texture, thickness, and color; capillitium well developed but variable in color, form, and extent; spore-ma.s.s dull black, sooty; spores spherical, purplish brown, nearly smooth, 7-9 .