. Fungi, ascomycetes, ustilaginales, uredinales. Fungi. io6 DISCOMYCETES [CH. In any case the greater part of the male cytoplasm does not enter the oogonium but is left behind in the antheridium and trichogyne; con- sequently these organs, after their function is complete, remain, to the superficial view, unchanged for a long period, till they are crushed at last by the growth of the investing hyphae, or perhaps destroyed by bacteria (Harper, p. 354). Before the stages described above, the oogonium has begun to bud out (fig. ) at various points, giving rise to the ascogenous hyphae. Into t
. Fungi, ascomycetes, ustilaginales, uredinales. Fungi. io6 DISCOMYCETES [CH. In any case the greater part of the male cytoplasm does not enter the oogonium but is left behind in the antheridium and trichogyne; con- sequently these organs, after their function is complete, remain, to the superficial view, unchanged for a long period, till they are crushed at last by the growth of the investing hyphae, or perhaps destroyed by bacteria (Harper, p. 354). Before the stages described above, the oogonium has begun to bud out (fig. ) at various points, giving rise to the ascogenous hyphae. Into these the nuclei pass, a few, no doubt unpaired, being left behind in the oogonium. The hyphae elongate, branch freely and undergo septation, and, as the vegetative filaments grow up, they ramify among them and at last bend over and give rise to asci from their penultimate cells. Claussen has described a paired arrangement of the nuclei in the ascogenous hyphae (fig. 63^), and believes the members of each pair to be respectively male and female. After the ascogenous and vegetative hyphae are thoroughly interwoven, a rapid stretching upward of the whole mass ensues. In this growth the vegetative hyphae outstrip the reproductive ones, and form at first a cone- shaped mass, made up of their elongated, slender, densely aggregated tips. These upper extremities of the vegetative hyphae are the young paraphyses. Their number is constantly increased by the pushing in of new branches from below, and thus the conical outline of the mass is maintained. The' ascogenous hyphae grow for a certain distance in company with the vegetative filaments, then their upward growth ceases, and they spread out horizontally, forming a rather dense layer below the cone of paraphyses. This is the base of the hymenium. Usually in Pyronema, as in Ascodesmis, several oogonia are invested by a common sheath, and their ascogenous hyphae mingle to form the hymeniurn of a single ascocarp (fig. 64), but ascocarps d
Size: 1330px × 1879px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectfungi, bookyear1922
