. Fundamentals of botany. Botany. LIFE HISTORIES OF EUNGI 269 261. Reproduction by Asci.—In late summer or early fall one may notice, on an infected leaf, among the my- celium, tiny black dots or spheres (Fig. 194), whence the name, Microsphara. Examined with the microscope, these bodies are seen to bear numerous appendages, branched at the end, and with the tips of the branches curved back to form miniature hooks (Fig. 195). When these little spheres are crushed, or when they burst open, they are found to con-. FiG. 194.—Powdery mildew {Microsphara Alni) on lilac leaf. An in- fected area from
. Fundamentals of botany. Botany. LIFE HISTORIES OF EUNGI 269 261. Reproduction by Asci.—In late summer or early fall one may notice, on an infected leaf, among the my- celium, tiny black dots or spheres (Fig. 194), whence the name, Microsphara. Examined with the microscope, these bodies are seen to bear numerous appendages, branched at the end, and with the tips of the branches curved back to form miniature hooks (Fig. 195). When these little spheres are crushed, or when they burst open, they are found to con-. FiG. 194.—Powdery mildew {Microsphara Alni) on lilac leaf. An in- fected area from the leaf in Fig. 193, greatly magnified. tain a number of tiny sacs or asci (singular ascus), whence the name "sac-fungus," or Ascomycete. In each ascus are a number of spores or ascospores, formed from the con- tents of the ascus. The young ascus is, therefore, a spore- mother-cell. There are usually eight ascospores in an ascus, but the number may vary. The spherical case containing the asci is the "spore- fruit" {ascocarp or perithecium), and results from the fusion of the contents of an antheridium and an oogonium. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gager, C. Stuart (Charles Stuart), 1872-1943. Philadelphia, P. Blakiston's son & co.
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