MYCELIUM.

De Leveille has thus defined mycelium: "Filaments at first simple, then more or less complicated, resulting from the vegetation of the spores and serving as roots to the mushroom."

The mycelium of mushrooms or the mushroom spawn is usually white, but is also found yellow, and even red. It is distinguished by some writers as nematoid, fibrous, hymenoid, scleroid or tuberculous, and malacoid. The nematoid mycelium is the most common. Creeping along on the surface of the earth, penetrating it to a greater or less depth, developing in manure among the débris of leaves or decayed branches, always protected from the light, it presently consists of very delicate filamentous cells more or less loosely interwoven, divided, anastomosing in every direction and often of considerable extent.

Its presence is sometimes difficult to detect without the use of the microscope, either on account of its delicacy or because of its being intermingled with the organic tissues in which it has developed.

Sometimes mycelium unites in bundles more or less thick and branched. This has been called the fibrous mycelium. Where the filaments intercross closely, are felted, and inclined to form a membrane, it is hymenoid mycelium. Where the filaments are so small and close that they form very compact bodies, constituting those solid irregular products called sclerotium, it is scleroid or tuberculous mycelium. With malacoid mycelium we have nothing to do in this paper. It is a soft, pulpy, fleshy mycelium.

Systematists have divided the Agaricini into groups according to the color of their spores. These groups are defined as follows by various authors:

According to—

Elias Fries, 5 groups: Leucosporus, white; Hyporhodius, pink; Cortinaria, ochraceous; Derminus, rust; Pratella, purplish black.

Rev. J. M. Berkeley, 5 groups: Very frequently pure white, but presenting also pink, various tints of brown, from yellowish and rufous to dark bister, purple-black, and finally black; Leucospori, white; Hyporhodii, salmon; Dermini, ferruginous; Pratellæ, brown; Coprinarius, black.

Dr. Badham, 6 groups: Pure white or a yellow tinge on drying; brown; yellow; pink; purple; purple-black; some pass successively from pink to purple and from purple to purple-black.

Mrs. Hussey, 11 shades: White; rose; pale ocher; olivaceous-ocher; reddish-ocher; ochraceous; yellowish olive-green; dull brown; scarcely ferruginous; snuff-color; very dark brown.

Hogg & Johnson, 5 groups: Leucosporei, white; Hyporhodii, salmon; Dermini, rusty; Pratellæ, purplish-brown; Coprinarii, black.

C. Gillet, 7 shades: White; pink; ochraceous; yellow; ferruginous; black or purplish black; round, ovate, elongated, or fusiform, smooth, tuberculate or irregular, simple or composite, transparent or nebulous, etc.

Jules Bel, 5 groups: White; pink; red; brown; black.

Dr. Gautier, 5 shades: White; pink; brown; purplish-brown; black.

Constantin & Dufour, 5 groups: White; pink; ochraceous; brownish-purple; black.

J. P. Barla, 7 groups: Leucosporii, white; Hyporhodii, pink; Cortinariæ, ochraceous; Dermini, rust; Pratellæ, purplish-black; Coprinarii, blackish; Coprini and Gomphi, dense black.

L. Boyer, 5 groups, 11 shades: White to cream yellow; pale pink to ochraceous yellow; bay or red brown to brown or blackish bister; rust color, cinnamon or light yellow.

W. D. Hay, 5 groups: White; pink; brown; purple; black.

C. H. Peck, 5 groups: Leucosporii, white; Hyporhodii, salmon; Dermini, rust; Pratellæ, brown; Coprinarii, black.

Saccardo divides the Agaricini into four sections, according to the color of their spores, as follows: Spores brown, purplish brown or black, Melanosporæ; spores ochraceous or rusty ochraceous, Ochrosporæ; spores rosy or pinkish, Rhodosporæ; spores white, whitish or pale yellow, Leucosporæ.

Dr. M. C. Cooke, 5 groups: Leucospori, white or yellowish; Hyporhodii, rosy or salmon color; Dermini, brown, sometimes reddish or yellowish brown; Pratellæ, purple, sometimes brownish purple, dark purple, or dark brown; Coprinarii, black or nearly so.

These shades are somewhat different from the colors of the mushrooms' gills, so that, when it is of importance to determine exactly the color of the spore in the identification of a species, we may without recourse to the microscope cut off the stem of an adult plant on a level with the gills and place the under surface of the cap upon a leaf of white paper if a dark-spored species, and upon a sheet of black paper if the spores are light. At the expiration of a few hours we will find, on lifting the cap, a bed of the shed spores which will represent their exact shade. These may be removed to a glass slide and their size and form determined by means of the microscope.

In the present work Dr. M. C. Cooke's grouping of the spore series is adopted.