Bulletin Volume 18-19

Bulletin Volume 18-19

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1899 edition. Excerpt: ...The embryo of grasses stands isolated from those of other monocotyledons in possessing two peculiar structures, the epiblast and plumule sheath. The following investigations were undertaken to determine the morphological significance and taxonomic value of these structures in the different tribes. Owing to the difficulties met with at the outset in securing a suitable method, the work is not so complete as at first anticipated The fruit of the Gramiaew was described first by Mirbel under the name "cerium" and rechristened later by Richard "caryopsis." Its contents at maturity consist largely of endosperm and embryo, the tissues of the nucellus, ovule, and ovary being almost completely displaced. The only remnants of the nucellus which are recognizable in the ripe grain are the empty cells which spring from the funiculus, and the epidermis of the nucellus, which is continuous as a very attenuated layer of cells around both endosperm. and embryo. Of the walls of the ovary only the inner one persists as a double layer of cells forming the testa or true_ coat of seed. Within the nucellus are one to four layers of cells with highly cuticularized walls. In section they are somewhat rectangular in form and constitute the gluten cells which contain the closely packed aleurone grains. Lying between the starch-containing portions of the endosperm and the embryo is a comparatively thick layer of compressed cells belonging to the scutellum. They are for the purpose of dissolving the starchy material of the endosperm during germination. The endosperm consists of thin-walled cells packed closely with starch granules, embedded in a fine mass of proteid material. These starch-containing cells each possess a nucleus which is not...show more

Product details

  • Paperback | 28 pages
  • 189 x 246 x 2mm | 68g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236915402
  • 9781236915405