The Monograph of the Gymnoblastic or Tubularian Hydroids. Plate III


Författare/Upphovsman:
George James Allman
Kreditera:
Allman G. J. The Monograph of the Gymnoblastic or Tubularian Hydroids. – Conclusion of Part I and Part II. – London: Robert Hardwicke, 1972. – Plate III
Kort länk:
https://sewiki.info/b/a5bd9
Källa:
Wikimedia Commons
Upplösning:
2531 x 3567 Pixel (4440938 Bytes)
Beskrivning:
Cordylophora lacustris (=Cordylophora caspia; Hydrozoa: Anthoathecatae: Filifera: Oceaniidae).
  • 1 – portion of a female colony, magnified:
    • a – very young gonophore;
    • b – gonophore more advanced, containing ova, which are embraced by the branches of a ramified spadix, and have their germinal vesicles distinct;
    • c – gonophore still further advanced; the ramifications of the spadix have disappeared, and the segmentation of the vitellus has been completed in the ova;
    • d – further stage of development, in which the ova have become planulae, and are ready to escape from the gonophore;
    • e – the gonophore has become ruptured at the summit, and the ciliated planulae are escaping into the surrounding water.
  • 2 – a colony of Cordylophora lacustris (=Cordylophora caspia), of the natural size, attached to the under surface of a piece of floating timber.
  • 3 – a male gonophore, the spermatic mass embraced by the ramifications of the spadix.
  • 4 – the distal portion of a male gonophore still more magnified:
    • a – external chitinous investment, showing layers of deposition;
    • b – ectotheca;
    • c – endotheca;
    • d – ramified spadix embracing the spermatic mass.
  • 5 – planula much magnified, in two different states of contracion. Its interior is occupied by a large cavity, and an ectoderm and endoderm are distinctly visible in its walls.
  • 6 – the planula after it has lost its cilia and has become fixed.
  • 7 – further stage of development, in which the distinction between stem and hydranth has become apparent, and a vertical of four tentacles has begun to be developed from the hydranth, while the stem has excreted a delicate chitinous perisarc.
  • 8 – the young Cordylophora still further developed; the tentacles are still in a single verticil, but have increased in length, and the hypostome has become prominent.
  • 9 – mature spermatozoa; in the group to the left heads are still enclosed in the generating cell.
Licens:
Public domain

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