. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. 304 EMBRYOLOGY prothallus. But, as soon as the root has become established in the soil, and the first leaf has spread out its lamina to the light, this dependence ceases, and soon after that the prothallus withers away (cf. Fig. 169, C). As compared with Bryophj'ta, the rela- tive importance of the two phases in the hfe-history is therefore reversed. The freediving sporophyte usually attains large dimen-. Fig. 169.—Embryology of the Fern. A, Longitudinal section through an archegonium, showing the octant-stag
. An introduction to the structure and reproduction of plants. Plant anatomy; Plants. 304 EMBRYOLOGY prothallus. But, as soon as the root has become established in the soil, and the first leaf has spread out its lamina to the light, this dependence ceases, and soon after that the prothallus withers away (cf. Fig. 169, C). As compared with Bryophj'ta, the rela- tive importance of the two phases in the hfe-history is therefore reversed. The freediving sporophyte usually attains large dimen-. Fig. 169.—Embryology of the Fern. A, Longitudinal section through an archegonium, showing the octant-stage in the division of the fertilised egg (after Sadebeck). B, Young embryo escaping from the pro- thallus {p.) (after Hofmcister). /., foot ; /., hrst leaf ; r., hrst root ; s., stem. C, Young plant, with the remains of the prothallus {p.) at the base, four unfolded leaves of increasing complexity, and one leaf not yet unfolded (original). sions and exhibits a complexity of structure which is only approached by the perennial gametophytes of some few Mosses. On the other hand, the sexual generation is as a general rule shortdived, though in a few Ferns (('.,i,'. the Royal Fern, Osiiiuiida) it persists for some years. Normally the two generations alter- nate regularly with one another, but occasional abnormalities 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 Fritsch, Felix Eugene, 1879-; Salisbury, E. J. (Edward James), Sir, b. 1886. London, G. Bell and sons ltd.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectpl, booksubjectplants
