. Nature and development of plants. Botany. 198 HIGHER TYPES OF REPRODUCTION orders of the Chlorophyceae, some of which are marine, that cannot be considered at this time. Two genera, however, de- serve attention because they show significant advances in the evolution of plant life. In Oedogonium, a member of a small order, the Oedogoniales, we find a still higher form of the sexual reproductive process. These plants are of very common occur- rence in ditches, streams and springs where their filaments form for a time greenish masses and coatings upon various objects, but finally become detache
. Nature and development of plants. Botany. 198 HIGHER TYPES OF REPRODUCTION orders of the Chlorophyceae, some of which are marine, that cannot be considered at this time. Two genera, however, de- serve attention because they show significant advances in the evolution of plant life. In Oedogonium, a member of a small order, the Oedogoniales, we find a still higher form of the sexual reproductive process. These plants are of very common occur- rence in ditches, streams and springs where their filaments form for a time greenish masses and coatings upon various objects, but finally become detached and free-floating (Fig. 115, A). Any of the cells of a filament, save the basal one, may form a single zoospore, which are large pear-shaped bodies with a narrow. Fig. 116. Sexual reproduction of Oedogonium: A, portion of a filament in which a female gamete has been formed—0, opening in cell wall for en- trance of male gamete. B, portion of filament showing formation and es- cape of male gametes. C, gametospore free from mother cell. The germi- nation of this spore results in the rupture of its outer wall and the protrusion of the contents of the spore as four cells which are for a time retained by the delicate inner wall of the spore, as shown in D. E, the four cells have become mobile zoospores and the delicate inner wall of the gametospore is greatly dis- tended and about to rupture. F, G, stages in the germination of the zoospore. —After Hirn. colorless end around the base of which arise a circle of numerous ciHa (Fig. 115, B, C). These zoospores develop into new plants (Fig. 115, D, E) as in previous cases.' The sexual reproduction presents a high degree of specialization. The male gametes are. 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 Curtis, Carlton Clarence, 1864-1945. New York, H. Holt
Size: 1699px × 1471px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublisher, booksubjectbotany
