Chapter VIII: FULIGO, Haller. Aethalium a compound plasmodiocarp; the component

sporangia branching and anastomosing in every direction, complicate and grown together; the walls of the sporangia a thin membrane, coated with minute, roundish granules of lime. Capillitium of tubules forming a net-work of irregular meshes, more or less expanded at the angles, the tubules containing in greater or less abundance irregular nodules of lime. Spores globose or sometimes ellipsoidal, violaceous.

The genus is readily distinguished from _Spumaria_ by the round granules of lime upon the walls of the sporangia.

§1. AETHALIUM, Link. Aethalia large; the lime in the capillitium scanty, the nodules small, ellipsoidal, or fusiform.

_a. Aethalium with a thick fragile common cortex._

1. FULIGO RUFA, Pers. Plasmodium a large soft mass with a peculiar odor and golden yellow in color. Aethalium very large, pulvinate, orbicular, elongated, or quite irregular, extremely friable, the surface tawny or ferruginous to ochraceous and whitish. The long narrow, sinuous sporangia closely compacted, entirely grown together and inseparable, covered by a thick common cortex, and seated on a much thickened hypothallus; walls of the sporangia a thin pellucid membrane, coated by a thin layer of white granules of lime. Capillitium of very slender tubules, extending across from wall to wall, sparingly branched and scarcely forming a network, not at all or only slightly expanded at the angles; the tubules for the most part empty, here and there with slight fusiform or elongated swellings containing granules of lime, occasionally bearing roundish or ellipsoidal nodules of larger size. Spores globose, nearly smooth, violaceous, 6-9 mic. in diameter.

Growing on old trunks in woods in great abundance from early Spring to Winter. Aethalium 3-6 or sometimes many centimeters in extent and 1-2 cm. in thickness. The common cortex and the hypothallus are a millimeter or more in thickness; they are composed of successive layers of thin plates of membrane coated with granules of lime.

_b. Aethalium naked, i. e., without a common cortex._

2. FULIGO VIOLACEA, Pers. Plasmodium a soft effused mass, dark red or wine-colored. Aethalium large, pulvinate or effused, orbicular or more or less elongated and irregular, the surface minutely pitted and perforate, furnished with a scanty layer of lime, whitish or yellowish to brick-red in color, leaving naked purple and violet spots and patches, seated on a thin membranaceous brick-red hypothallus. Sporangia long, narrow, and sinuous, closely packed together; the walls a thin violaceous membrane, rugulose and iridescent, with scattered granules, or nearly destitute of lime. Capillitium of slender violet tubules, forming a loose net-work, with slight expansions at the angles; the tubules with numerous rather large vesicular expansions, ellipsoid or fusiform in shape, and scantily furnished with lime. Spores globose, nearly smooth, pale vinous, 6-8 mic. in diameter.

Growing on old trunks in woods; not uncommon in this region. Aethalium 1-3 or more centimeters in extent, and 5-10 mm. in thickness. The vesicles of the capillitium vary from 15-30 or sometimes to 50 mic. in diameter, their inner surface is usually coated by a single layer of granules of lime, they are rarely filled with lime and sometimes are naked entirely; when dry many of them are to be found collapsed.

3. FULIGO FLAVA, Pers. Plasmodium effused lemon-yellow. Aethalium mostly effused, irregular, the surface reticulate, pitted and perforate, entirely naked, pale yellow to lemon-yellow and greenish-yellow, the hypothallus thin or scarcely evident. Sporangia laterally much compressed, flexuous, and gyrose, not everywhere grown together, but forming a dense reticulum; the walls a thin, pellucid membrane, with a dense layer of lemon-yellow granules of lime. Capillitium of short and very slender tubules, sparingly branched and scarcely forming a net-work, not expanded at the angles; the tubules very scantily furnished with lime, in scattered, small, fusiform nodules, white or lemon-yellow. Spores globose, very minutely warted, violaceous, 7-9 mic. in diameter.

Growing on mosses, old leaves, sticks, etc.; not common. Aethalia in irregular patches 2-4 cm. or more in extent, sometimes almost reduced to a simple plasmodiocarp. This species furnishes a clear notion of the structure of the aethalium in the other species, on account of the sporangia being but loosely compacted and not entirely grown together. The _Fuligo vaporaria_ Pers., of the green-houses and gardens I have never seen; the _Mucor septicus_ Linn., was thought to be the plasmodium of this. Linnæus's description is simply "_Mucor unctuosus flavus._"

§2. AETHALIOPSIS, Zopf. Aethalium small; lime abundant in the capillitium, the nodules numerous and large, angular and irregular.

4. FULIGO MUSCORUM, A. & S. Plasmodium effused, golden yellow. Aethalium small, subpulvinate, irregular, the surface furnished with scattered, irregular scales of lime, whitish or ochraceous to golden yellow in color, arising from a thin, white, membranaceous hypothallus. Sporangia closely packed and grown together; the walls a thin, violaceous membrane, rugulose, with a thin, closely adherent layer of granules of lime. Capillitium a loose net-work of tubules, widely expanded at the angles; the tubules for the most part filled with lime, the nodules white or yellowish, numerous, very large, angular and irregular, sometimes confluent with pointed lobes and branchlets. Spores irregularly globose, minutely warted, dark violaceous, 9-11 mic. in diameter.

Growing on leaves, twigs, mosses, etc. Aethalium from 2 or 3 mm. to a centimeter or more in extent. I have a specimen of _Fuligo simulans_ Karsten, from Karsten himself; it is identical with my specimens of _Fuligo ochracea_ Peck. There could be no better representation of these specimens made at that time than the description and figure of _Fuligo muscorum_ A. & S., in the _Conspectus_.

5. FULIGO CINEREA, Schw. Plasmodium milk-white, changing to cinereous. Aethalium effused, variable in extent, the surface rugulose and perforate, white, the hypothallus thin or scarcely evident. Sporangia variously contracted and grown together, forming a dense reticulum; the walls a thin pellucid membrane, with a thick white outer layer of granules of lime. Capillitium a loose net-work of tubules, widely expanded at the angles, the tubules for the most part filled, with lime, the nodules white, numerous, very large, angular, and irregular, lobed and branched. Spores globose or oval, minutely warted, dark violaceous, 10-15 × 10-12 mic.

Growing on old leaves, herbaceous stems, etc. I find it most abundantly about the horse barn, upon the old straw and manure, sometimes running out onto the green herbage. Aethalium from a few millimeters to several centimeters in extent. Upon the testimony of Dr. Geo. A. Rex this is both _Enteridium cinereum_ and _Lachnobolus cinereus_ of Schweinitz's _North American Fungi_ as represented in his herbarium. It is _Physarum ellipsosporum_ of Rostafinski. It is no doubt also _Aethaliopsis stercoriformis_ Zopf.