Abstract
THE COMET-FORMS OF STAR-FISHES.—Ernst Haeckel, in a recent number of the Zeitsch. wiss. Zool. (1878, Supplement 3), draws attention to these forms, and the support which the facts recently established as to the power possessed by certain star-fishes of multiplying by throwing off their arms, lends to his theory of the origin of the Echinoderma by the continually increasing integration or centralisation of a radially-connected colony of worm-like persons. The phenomenon of self-division across the disc has been observed in species of Asteracanthion (Uraster) by Lütken and Kowalewsky; the production of comet-forms depends, however, on the separation of single arms, which then reproduce the whole disc and remaining arms by budding. Martens, in 1866, observed this in the case of a Luidia (Ophidiaster) in the Red Sea. Kowalewsky found that it was a common process with similar species and same locality. Sars observed it in Brisinga. Studer has described the regular occurrence in Labidiaster of a spontaneous casting off of the arms, but not the regeneration of disc and arms on the sepa-irated arms. Sir John Dalyell observed the whole process of reproduction of the disc on a single detached arm of Asteracanthion (Uraster) glacialis. The support which these facts lend to the “Astrocormus” theory is not of that value which Haeckel would assign to them, for such physiological tests of morphological doctrine are necessarily delusive. We have only to remember the facts as to cuttings and graftings in organisms generally in order to see that no special argument can be based upon them as to details of morphological composition. Haeckel proposes to diride the Echinoderms or Estrellae as follows:—
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L., E. BIOLOGICAL NOTES . Nature 18, 252–253 (1878). https://doi.org/10.1038/018252a0
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DOI: https://doi.org/10.1038/018252a0