Histochemical Observations on the Discomycete, Pyronema Domesticum, with Special Reference to Apothecial Ontogeny

SUMMARY

Histochemical tests were conducted on apothecia of the discomycete, Pyronema domesticum, which had been fixed, sectioned, and prepared for light microscopy. Positive tests were obtained for glycogen and other carbohydrates, mucilage, protein, DNA, RNA, lipids, and phospholipids. Negative tests were obtained for melanin, starch, and cellulose. The distribution of carotenes was also observed. Some cellular constituents were especially abundant during the early phases of growth and diminished slightly during maturation: these were the carbohydrates (exclusive of glycogen), protein, DNA, RNA, phospholipids present in granules (presumably mitochondria), and carotene pigments. The foregoing components were abundant in the gametangia and were similar in their distribution in the sterile and ascogenous systems. Glycogen and diffuse lipids were generally absent in the gametangia and early developmental stages, but accumulated later. Glycogen was especially conspicuous in the ascogenous system, while the diffuse lipids were more conspicuous in the sterile system. A thin layer of secreted mucilage covered most of the apothecial components, and originated after the apothecium was initiated. The gametangia as well as most other parts of the apothecium appeared to be active in the production of these components in situ. Although the paraphyses often gave strong positive tests for various constituents, the excipular hairs were notably deficient.