New Mallophaga Volume 7

New Mallophaga Volume 7

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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. 1896 edition. Excerpt: ...very much in size, finally reaching enormous dimensions, but never showing any indication of division1. This, as Schaffner has shown, is also true for Alisma; and Scott (1894, pp. 187, 188) in a recent work has reached the same conclusion, although it is not clear from his statement whether he considers the middle of the three cells of the young embryo as arising from the division of the upper or lower of the two primary cells. Following these transverse walls in the young embryo, there is next formed a vertical wall in the terminal cell, which latter develops into the single terminal cotyledon of the older embryo. This is next followed by a similar wall in the cell below it, and about the same time, by a transverse wall in the cell next the enlarged basal cell. At this stage the embryo consists (fig. 64) of the very much enlarged basal cell, followed by two short secondary suspensor cells, and terminated by a nearly globular body composed of four cells arranged like the quadrants of a sphere. Each of these sphere-quadrants next divides by octant walls, and from the upper four arises the cotyle 'This appears to be much leas marked ill N. major (see Magnus, 1870, p. 31). don; from the lower ones, the middle part of the embryo and stem-apex. There is now formed in each octant cell a periclinal wall, separating it into an inner and outer one, the latter constituting the dermatogen of the upper part of the embryo (fig. 65). While these changes have been going on in the upper part of the embryo, the cell next below has enlarged laterally, and the one below this divided again. In the former there are then formed quadrant walls, and each of the quadrant cells next separates into a peripheral, or epidermal cell, and an inner one, exactly as was...show more

Product details

  • Paperback | 166 pages
  • 189 x 246 x 9mm | 308g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236978331
  • 9781236978332