The four primary sections are the Mucedineae, or "white moulds;" the Dematieae, or "black moulds;" the Stilbea, with the hyphae or thread-like filaments pallid or brown, and densely cohering, and the Tubercularieae, with the hyphae densely compacted in wart-like pustules of somewhat gelatinous consistency.

The divisions called Melanconieae, Sphaeropsideae, and Hyphomyceteae are not recognized in the Brefield system of cla.s.sification as distinct groups.

Ma.s.see and Cooke, with other mycologists, take exception to this omission and its implication, in their discussion of the subject, giving consistent reasons for the retention of these groups in systematic works.

PHYCOMYCETES OR PHYSOMYCETES.

As originally defined by Berkeley, this group was composed chiefly of the old typical Mucors and their allies, and was then termed Physomycetes. In the newer system of cla.s.sification its original definition has been extended so as to include a number of groups somewhat dissimilar in their habits and characteristics, but "united under the conservating bond of a dimorphic reproduction," and the name has been changed to Phycomycetes. As at present recognized "the Phycomycetes are characterized by a unicellular mycelium, often parasitic on plants or animals, sometimes saprophytic, developed in the air or in water. Reproduction s.e.xual or as.e.xual." As thus interpreted, Phycomycetes includes the Mucoracei; the Peronosporaceae, or "rotting moulds;" the Cystopi, or "white rusts;" the Saprolegniaceae, or "fish moulds;" the Entomophthoraceae, or "insect moulds," together with a few minor groups of doubtful natural affinity.

BIBLIOGRAPHY.

Saccardo, P. A. "Sylloge Sphaeropsidearum et Melanconiearum," in Sylloge Fungorum. Vol. iii. Imp. 8vo. Padua, 1884.

L. A. Crie. _Recherches sur les Pyrenomycetes inferieurs du group de Depazees._ 8vo. Paris, 1878.

J. C. Corda. _Icones Fungorum._ Fol. 6 vol. Prague, 1837-'54.

Bonorden. _Zur Kenntniss der Coniomyceten u. Cryptomyceten._ 4to. Halle, 1860.

M. C. Cooke. _The Hyphomycetous Fungi of the United States._ 8vo. 1877.

P. A. Saccardo. _Sylloge Fungorum._ Vol. iv.--"Hyphomyceteae." Padua, 1886.

De Toni, J. B. "Sylloge Ustilaginearum et Uredinearum," in Saccardo, _Sylloge Fungorum._ Imp. 8vo. Vol. vii, pt. ii. Padua, 1888.

Geo. Winter in Rabenhorst's _Kryptogamen Florader Pilze_. 8vo. Cuts.

1884.

Geo. Ma.s.see. _British Fungi--Phycomycetes and Ustilagineae._ 8vo. Cuts.

London, 1891.

O. Brefield. _Bot. Untersuch. u. Hefenpilze._ Leipzig, 1883.

Tulasne. "Memoire sur les Ustilaginees comparees aux Uredinees." Ann.

des Sci. Nat., 3d series, vol. vii. Paris, 1847.

M. Woronin. Beitrag zur Kenntniss der Ustilagineen. 1882.

M. C. Cooke. Rust, s.m.u.t, Mildew, and Mould. 12mo. Col. plates. London, 1870.

C. B. Plowright. _A Monograph of the British Uredineae and Ustilagineae._ 8vo. London, 1889.

W. C. Smith. _Diseases of Field and Garden Crops._ 12mo. Cuts. London, 1884.

D. D. Cunningham. _Conidial Fructification in the Mucorini._

R. Thaxter. "The Entomophth.o.r.eae of the United States." Memoirs of Boston Society of Natural History. Vol. iv, 4to. Plates. 1888.

L. Mangin. _Sur le Structure des Peronosporees._ Paris, 1890.

K. Lindstedt. _Synopsis d. Saprolegniaceen._ 8vo. Four plates. Berlin, 1872.

M. Cornu. "Monographie des Saprolegniees." Ann. des Sci. Nat., 5th series. Vol. xv. Paris, 1872.

M. C. Cooke. _Synopsis Pyrenomycetum._ 2 parts. 8vo. London, 1884-'86.

A. de Zaczewski. "Cla.s.sification naturelle des Pyrenomycetes." Bull.

Soc. Myc. de France, vol. x. 1894.

J. B. Ellis and B. M. Everhart. _The North American Pyrenomycetes._

M. C. Cooke. _Mycographia,_ vol. i. "Discomycetes." Col. plates. Imp.

8vo. London, 1879.

W. Phillips. _A Manual of British Discomycetes._ Im. 8vo. Plates.

London, 1887.

P. A. Saccardo. "Sylloge Discomycetum," in _Sylloge Fungorum_. Vol.

viii. Padua, 1889.

R. Hartig. _Text Book of Diseases of Trees._ Roy. 8vo. London, 1894.

Geo. Ma.s.see. The Evolution of Plant Life, Lower Forms. 12mo. London, 1891.

Marshall Ward. Diseases of Plants. 12mo. Cuts. London, 1884.

A. De Bary. _Recherches sur le Developpement de quelques champignons parasites._ 8vo. Plates. Berlin, 1878-'94.

APPENDIX.

_Superior_, the upper surface; applied to the ring when near the apex of the stem.

_Tetraspore_, _tetra_ Gr. four; spores.

_Theca_, cell-mother, the protoplasm of which originates by segmentation; a certain number of spores, usually eight, held in suspension in the protoplasm of the theca without being attached to each other or to the cell walls.

_Thecaspore_, the spore thus encased.