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Conspicuous gelatinous tissues, consisting of gel and hyphae, occur in fungi in the discomycete subfamilies Ombrophiloideae and Leotioideae and in the basidiomycete order Tremellales. The origin and subsequent development of gelatinous tissues in representative species were investigated. Fungal gels may be selectively stained with the mucin stain, mucicarmine, and metachromatically with toluidine blue. Gel was found to arise in 2 fundamentally different ways, by hyphal disintegration and by direct secretion of mucilage from the protoplasm. With hyphal disintegration a swelling of the hyphal walls may precede the formation of the gel, as occurs in the conidiophores of Coryne cylichnium, or the hyphae may disintegrate directly to form the gel, as occurs in the basidiocarp of Pseudohydnum gelatinosum. Mucilage secretion occurs in the discomycetes Bulgaria inquinans, Coryne cylichnium, Corynella sp., Cudonia lutea, Holwaya leptosperma, Leotia viscosa, Neobulgaria pura, and Neobulgaria sp. Mucilage is secreted directly from the hyphae, except in the imperfect stage of H. leptosperma in which specialized secretory cells occur. Deeply staining material aggregates in the hypha or cell and is then extruded through small pores in the walls. A subsequent change in viscosity occurs and the mucilage becomes gelatinous. If produced in small amounts, the gel ensheaths the hyphae and collects in the interhypbal spaces in a loosely organized tissue, or forms interstitial gel in a compactly organized tissue. If gel is produced in large amounts it will form a continuous gel matrix regardless of the tissue type. Sites of unusually heavy gel production (here termed “gliatopes”) may be formed in either rapidly developing or confined tissue. Both mucilage secretion and hyphal disintegration to form gel occur in the cupulate coremium of the imperfect stage of C. cylichnium.

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