. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. 30 MORPHOLOGY OP SPERMATOPHYTES organ and later became used as a sperm carrier, or whether the reverse is true. It would seem natural to think of the Cyead condition as the more primitive one. IV. THE EMBRYO The first comparatively full account of the development of the embryo is that given by Treub i* for Gycas circinalis, and this account has been confirmed by fragmentary observations since. The account given by Ikeno ^^ for Cycas revoluta agrees. Fig. 26.—Oycas circinalis, development of the embryo: A, an
. Morphology of spermatophytes. [Part I. Gymnosperms]. Gymnosperms; Plant morphology. 30 MORPHOLOGY OP SPERMATOPHYTES organ and later became used as a sperm carrier, or whether the reverse is true. It would seem natural to think of the Cyead condition as the more primitive one. IV. THE EMBRYO The first comparatively full account of the development of the embryo is that given by Treub i* for Gycas circinalis, and this account has been confirmed by fragmentary observations since. The account given by Ikeno ^^ for Cycas revoluta agrees. Fig. 26.—Oycas circinalis, development of the embryo: A, an ovule from above, show- ing the openings of the necks of several arohegonia, x %\ B, longitudinal section of an archegonium, x 73; C, a fertilized egg, showing several free nuclei, x 24; D, free nuclei of the proembryo, showing parietal placing, x 36; ^, a young pro- embryo, X 15; X a young embryo, showing saclike proembryo, suspensor (fusp), and embryo proper (e), x 6; ff, longitudinal section of seed containing two embryos, two thirds natural size; ff, embryo with suspensor, x IJ^; J, a more advanced em- bryo, two thirds natural size; K, a mature embryo.—After Tkedb (from Engler and Prautl's Nat. Pflanzenfam.). in every particular with Treub's, and fills in certain gaps. There is still almost entirely lacking any knowledge of the devel- opment of the embryo itself. The embryogeny shows three dis- tinct phases as follows (Fig. 26): 1. Development of Proembryo.—This name was applied by Treub to the intrasporic development. The oospore en- larges, continuing to receive supplies of nutrition from the adja- cent tissue. The first change observed by Treub was the pres-. 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 Coulter, John Merle, 1851-1928; Chamberlain, Charles Joseph, b. 1863. New York, D. Appleto
Size: 1852px × 1349px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcoulterj, bookcentury1900, bookdecade1900, bookyear1901
