Fish Parasites Collected at Woods Hole in 1898

Fish Parasites Collected at Woods Hole in 1898

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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. 1900 edition. Excerpt: ...a mass of yolk left the reservoir until it was ejected as a completed capsule was about 40 seconds. 2. Confirmation of some of the above-mentioned inferences.--Sections, both transverse and herizontal, were made of this interesting worm. The results were highly satisfactory, but the anatomioal details are so numerous as to be altogether out of place in this report. I shall mention only certain details of structure which explain some of the phenomena of ovulation narrated above. The duct which leads from the yolk reservoir passes dorsally (fig. 14, yd), hence can not be seen plainly, either in dorsal or ventral view, in the living specimen. The duct from the germ gland also has its outlet dorsally, and the two connect in such a mauner that when a mass of yolk rushes along the yolk duct and into the common duct, a suction would be created which would tend todraw a germ from the germ duct. While the germ duct is spacious at its beginning in the germ gland, which feature, indeed, could be seen plainly in the living specimen, where numerous ripe germs could be seen oscillating every time a charge of yolk passed toward the shell mold, the duct grows narrower distally, and at a shert distance from the point of uuion with the yolk duct is but little wider than the diameter of a single germ. Since the amount of yolk which is necessary for a single egg is doubtless regulated by roflex nervous action, the whele apparatus has become adjusted with wonderful nicety, the several parts to each other, so that, when normal conditions prevail, just enough suction is created by the charge of yolk to draw a single waiting germ (ell from the germ duct. Another fact demonstrated by serial sections is that at a point but a shert distance from the junction of...show more

Product details

  • Paperback | 30 pages
  • 189 x 246 x 2mm | 73g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236792114
  • 9781236792112