ASCOMYCETES.
Fruit, consisting of sporidia, mostly definite, contained in asci, springing from a naked or enclosed stratum of fructifying cells, and forming a hymenium.—Cooke and Berkeley.
Prof. J. de Seyne states that the three elements which form the hymenium in the families Hymenomycetes and Gasteromycetes are (1) the normal basidium, that is, the fruitful club-shaped cell which supports the naked spores, (2) the cystidium or sterile cell, an aborted or atrophied basidium, and (3) the paraphyses, hypertrophied basidium, the one organ, the basidium, being the basis of it all, according as it experiences an arrest of development, as it grows and fructifies, or as it becomes hypertrophied.
In the family Ascomycetes a minute ascus or spore case envelops the sporidia, and takes the place of the basidium, and the hymenium consists of (1) the asci containing the sporidia, (2) the paraphyses, and (3) a colorless or yellowish mucilage which envelops the paraphyses and asci. The asci are present in all species. In some species, however, the paraphyses are rare, and the mucilaginous substance is entirely wanting. The asci differ in shape and size, according to the species. The paraphyses, when present, are at first very short, but they rapidly elongate, and are wholly developed before the appearance of the asci. They are linear, simple or branched according to the species of plant, usually containing oily granules. There is some difference of opinion among mycologists as to the special functions of the paraphyses, some considering them as abortive asci, and others, like Boudier, as excitatory organs for the dehiscence of the asci, by which the spores are liberated.
The family Ascomycetes is rich in genera and species.
It consists largely of microscopic fungi, however, and the only group which will be considered here is that which includes plants of the mushroom family which are edible and indigenous to this country, viz., the sub-family Discomycetes.
DISCOMYCETES.
The name Discomycetes, "disk-like fungi," does not give an accurate idea of the distinguishing characteristics of this sub-family, the discoid form only belonging to the plants of one of its groups. In the Discomyceteæ the hymenium is superior, that is, disposed upon the upper or exterior surface of the mushroom cap. The sporidia are produced in membraneous asci, usually four or eight, or some multiple of that number, in each ascus; Cooke says "rarely four, most commonly eight." The sporidia are usually hyaline, transparent; colored sporidia are rare.
The asci are so minute as to be imperceptible to the naked eye; but if a small portion of the upper surface of the cap is removed with a pen knife and placed under a microscope having a magnifying power of from 400 to 800 diameters, the asci, or spore sacks, can be separated and their structure studied.