The structure & development of the mosses and ferns (Archegoniatae) . Marsilia vestita (Hook and Grev.). A, Fruiting plant of the natural size; sfi,sporocarps; B, a single sporocarp, X4; C, cross-section of the same, X 5 ; D, germinatingsporocarp, showing the gelatinous ring by which the sori (.r) are carried out, x 3. fruit. As more water is absorbed, this gelatinous inner tissuecontinues to expand and forms a long worm-shaped body (, D), to which are attached a number of sori, each surroundedby a sac-shaped indusium in which the sporangia are closelypacked. Macrosporangia and microspo
The structure & development of the mosses and ferns (Archegoniatae) . Marsilia vestita (Hook and Grev.). A, Fruiting plant of the natural size; sfi,sporocarps; B, a single sporocarp, X4; C, cross-section of the same, X 5 ; D, germinatingsporocarp, showing the gelatinous ring by which the sori (.r) are carried out, x 3. fruit. As more water is absorbed, this gelatinous inner tissuecontinues to expand and forms a long worm-shaped body (, D), to which are attached a number of sori, each surroundedby a sac-shaped indusium in which the sporangia are closelypacked. Macrosporangia and microsporangia occur in thesame sorus. The former contain a single large oval whitespore, the latter much more numerous small globular indusium remains intact for several hours, if not injured, 400 MOSSES AND FERNS CHAP. but finally, with the sporangium wall, is completely dissolved,and the spores set free. The Microspores and Male ProtJiallium The microspores of M. vestita (Fig. 207) are globular cellsabout .075 mm. in diameter. The outer wall is colourless and. Fig. 207.âMa?-silia vestita. (Hook and Grev.). Germination of the microspores, X450; x^ vegetative prothallial cell; m, basal antheridial cell; /, peripheral antheridial cells; A, an ungerminated spore, ventral aspect ; B, section of a similar oneâall longitudinal sections except E and F, which are transverse. In these the two groups of sperm cells are separated by alarge sterile cell. sufficiently transparent to allow the contents to be dimly close to the wall are numerous distinct starch granules,and in the centre the nucleus is vaguely discernible. Sectionsthrough the ungerminated spore show that the wall is thick,with an inner cellulose endospore, outside of which are the XII .401 exospore and the epispore or perinium, composed of closely-setprismatic rods. The central nucleus is large and distinct, withusually one or two nucleoli. The first division takes place at ordi
Size: 1585px × 1577px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookidstructuredev, bookyear1895
