. Botany; principles and problems. Botany. 290 BOTANY: PRINCIPLES AND PROBLEMS 1. Mucorales, the True Molds or Black Molds (Fig. 164).— These fungi are very common on moist, decaying organic material such as manure, rotting fruit, and the hke. Their white, cob- webby mycehum, composed of much-branched hyphae, freely penetrates the substratum in all directions. From the surface, stout hyphae arise into the air and bear at their tips globular. Fig. 165.—Mucor. Formation and germination of the zygospore. A, two conjugating hyphae in contact. B, a gamete, a, has been cut off from the end of each h
. Botany; principles and problems. Botany. 290 BOTANY: PRINCIPLES AND PROBLEMS 1. Mucorales, the True Molds or Black Molds (Fig. 164).— These fungi are very common on moist, decaying organic material such as manure, rotting fruit, and the hke. Their white, cob- webby mycehum, composed of much-branched hyphae, freely penetrates the substratum in all directions. From the surface, stout hyphae arise into the air and bear at their tips globular. Fig. 165.—Mucor. Formation and germination of the zygospore. A, two conjugating hyphae in contact. B, a gamete, a, has been cut off from the end of each hypha. C, the enlarged gametes. D, thick-walled zygospore which has arisen from a union of the two gametes. E, zygospore germinating to form a sporangium. {From Slrasburger, after Brefeld). sporangia which burst and liberate masses of dark-colored spores, each of which may germinate directly into a new plant. Sexual reproduction is isogamous or essentially so (Fig. 165). Two short branches or suspensors, arising from adjacent hyphae, approach one another and come into contact end-to-end. From the tip of each is cut off a single multinucleate cell which is the gamete, and these two adjacent gametes fuse to produce a thick- walled zygospore. It has been found that two distinct sexual strains often exist, entirely similar outwardly but functioning quite differently in reproduction. These have been called the plus and the minus strains and correspond to the two sexes, for. 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 Sinnott, Edmund Ware, 1888-. New York, McGraw-Hill
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