BREFIELD'S CLASSIFICATION OF FUNGI.

A system of classification of fungi which is receiving attention from mycologists is that recently presented by the distinguished German author Dr. Oscar Brefield. Dr. Brefield's exhaustive investigations into the life-history of fungi in general have been such as to entitle his views to consideration, although the system presents some inconsistencies which may prevent its adoption in its entirety.

According to the Brefield system, as summarized by his colleague Dr. Von Tavel, Fungi are divided into two primary classes: (1) the Phycomycetes, or lower fungi nearest like the algæ, consisting of a one-celled thallus with sexual as well as non-sexual modes of reproduction, and (2) the Mesomycetes and the Mycomycetes, having a divided or many celled thallus, propagated by non-sexually formed spores. The Phycomycetes are further divided into two large sections, based on their methods of reproduction, termed, respectively, Zygomycetes and Oomycetes. These include the old typical Mucors, the Peronosporeæ or "rotting moulds," once classed with the Hyphomycetes, the Saprolegniaceæ, "Fish Moulds," of aquatic habit, the Entomophthoraceæ, "Insect Moulds," together with some minor groups. The Mesomycetes connect the Phycomycetes with the Mycomycetes. The class Mycomycetes is primarily divided into two sections, viz., Ascomycetes and Basidiomycetes, with the Ustilagineæ, "Smut Fungi," in Mesomycetes, forming a transitional group between Phycomycetes and the Basidiomycetal group of the higher fungi.

The Ascomycetes are primarily subdivided into Exoasci and Carpoasci, groups based on the character of the asci. In the first, Exoasci, the asci are naked and borne directly on the mycelium; in the second, Carpoasci, they are enclosed in a wrapper composed of fertile hyphæ and sterile threads, having also accessory fruit forms. The first includes Endomycetes and Taphrineæ. In the second are included the groups Gymnoasci, Perisporaceæ, Pyrenomycetes, Hysteriaceæ, Discomycetes, and Helvellaceæ.

The Basidiomycetes characterized by the possession of basidia are arranged in two groups, based on the character of the basidia: (1) the Protobasidiomycetes, in which the basidia are septate, divided, and (2) the Autobasidiomycetes, in which the basidia are not divided, and bear a definite number of spores.

The first of these (Protobasidiomycetes) includes the following distinct groups: (1) the Uredineæ, "Rust Fungi," which have horizontally divided basidia, always free, never enclosed; (2) the Auricularieæ, having basidia somewhat resembling those of the Uredineæ, but which are borne in fruit bodies with open hymenia; (3) Pileacreæ, having horizontal septate basidia in closed receptacles; and (4) Tremellineæ, having vertically divided basidia borne in gymnocarpous receptacles—that is, those in which the hymenium is exposed while the spores are growing.

The Autobasidiomycetes are characterized by undivided basidia, bearing spores only at the apex. This group is subdivided into three sections: (1) Dacryomycetes, which includes the lowest of the Tremelloid forms, with club-shaped basidia, nearly approaching the true Hymenomycetal type, together with several groups of minor import; (2) Gasteromycetes; and (3) Hymenomycetes, with Phalloideæ placed in the group as a subsection of Gasteromycetes.

The above can only be considered as a very brief abstract of the system of classification proposed by Dr. Brefield, but it will serve to give some idea of the principle on which the system is based, which is sufficient for our present purpose. Those who wish to study the system in detail will find it treated in a comprehensive manner in Dr. Von Tavel's summary as it appears in the Vergleichende Morphologie der Pilze, Jena, 1892.