A history of the British zoophytes / [George Johnston].

  • George Johnston
Date:
1838
Catalogue details

Licence: Public Domain Mark

Credit: A history of the British zoophytes / [George Johnston]. Source: Wellcome Collection.

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    Ellis taught no novel doctrine, but he gave it fixidity and currency ; and he moreover applied it to those very zoophytes which possessed the vegetable appearance in the most perfec- tion, many of which he was the first to notice, and which he il- lustrated with a series of figures of unequalled accuracy. * He rarely went beyond the mere statement of the facts witnessed, or what seemed an unavoidable inference from them; but, per- haps, he deserted his usual caution when, from analogy princi- pally, he asserted that the articulated calcareous corallines (Co- rallina, Zin.) and sponges, of a very different structure from coral, madrepore, or the horny corallines, were also hke them, manifestly the places of abode of different species of polypes. In the former (Corallina) he had indeed detected some slender fibres which, it was presumed, might be parts of polypes, but this observation he was never able to confirm, and it was rather because of the porous structure of the corallines, than from any thing else, that he inferred the existence of polypes in them,— a structure which he had examined with minute accuracy, and shown to be essentially different from any known vegetable tis- sue,—and, secondly, because of their chemical ccnstituents, of which he procured an accurate analysis to be made.— With re- gard to the Sponges, Ellis, as Peyssonnel had previously done, supposed at first that the regular holes observable in dry speci- mens, strongly indicated their being once filled with animals ; but when after repeated examinations of recent sponge, he could detect none, this conjecture was abandoned, and so thoroughly zoophytes was the principal fact for placing them in the animal kingdom.— Book of Nature, i. 175 and 210. * As mentioned above, Bernard de Jussieu knew that the Sertulariade—the zoophytes here alluded to—were animal productions, but no detailed account of his observations seems ever to have been published. Trembley had made the same discovery. Dr Watson, in his account of Peyssonnel’s treatise in 1752, tells us that Mr Trembley shewed him, “ at the late excellent Duke of Rich- mond’s” the small white polypes of the Corallina minus ramosa alterna vice den- ticulata of Ray, “exactly in form resembling the fresh-water polype, but infinite- ly less.” “ When the water was still, these animals came forth, and moved their claws in search of their prey in various directions ; but, upon the least motion of the glass, they instantly disappeared.” P. 463.—Linnzus, however, in refer- ence to the observations made previous to Ellis, says they are “ inchoate, non ad plenum confecte, et desiderentur adhuc quam plurima, que dies forte reve- labit.—-Amoen. Acad. Vol. i. p. 186.
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