. Elementary botany. Botany. 122 MORPHOLOGY. rangium becomes dissolved, except a small collar around the stalk which remains attached below the columella (fig. 133).. Fig. 132. s nigricans, ing from an older group. Group of sporangia of a mucor (Rhizopus nigricans) showing rhizoids and the stolon extend- ; fro By this means the gonidia -are freed. These gonidia germinate and produce the mycelium again. 277. Sexual stage.—This stage is not so frequently found, but may some- times be obtained by growing the fungus on bread. Conjugation takes place in this way. Two threads of the mycelium which l
. Elementary botany. Botany. 122 MORPHOLOGY. rangium becomes dissolved, except a small collar around the stalk which remains attached below the columella (fig. 133).. Fig. 132. s nigricans, ing from an older group. Group of sporangia of a mucor (Rhizopus nigricans) showing rhizoids and the stolon extend- ; fro By this means the gonidia -are freed. These gonidia germinate and produce the mycelium again. 277. Sexual stage.—This stage is not so frequently found, but may some- times be obtained by growing the fungus on bread. Conjugation takes place in this way. Two threads of the mycelium which lie near each other put out each a short branch which is clavate in form. The ends of these branches meet, and in each a septum is formed which cuts off a portion of the protoplasm in the end from that of the rest of the my- celium. The meeting walls of the branches now dissolve and the protoplasm of each gamete fuses into one mass. A thick wall is now formed around this mass, and the outer layer becomes rough and brown. This is the zygote or zygospore. The mycelium dies and it becomes free often with the suspensors, as the stalks of these sexual branches are called, still attached. This zygo- spore passes through a period of rest, when with the entrance of favorable conditions of growth it germinates, and usually produces directly a sporan- gium with gonidia. This completes the normal life cycle of the plant. 278. Gemmae.—Gemmae, as they are sometimes called, are often formed on the mycelium. A short cell with a stout wall is formed on the side of a. 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 Atkinson, George Francis, 1854-1918. New York, H. Holt
Size: 1873px × 1335px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublisher, booksubjectbotany
