On the morphology of the reproductive system of the Sertularian zoophyte, and its analogy with the reproductive system of the flowering plant / By Edward Forbes.

  • Edward Forbes
Date:
1844
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Licence: Public Domain Mark

Credit: On the morphology of the reproductive system of the Sertularian zoophyte, and its analogy with the reproductive system of the flowering plant / By Edward Forbes. Source: Wellcome Collection.

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    knowledge of the plant will enable us to throw light on the na¬ ture and regulating laws of the composite animal, at present very obscurely understood. The present communication is intended to show, that in one tribe at least of composite animals, in the Sertularian Polypes, the arrangement and offices of individuals and of the parts of the ani¬ mal entirely depend on the same laws which determine the ar¬ rangement and offices of the parts of the composite plant. The Sertularian Polype is a branched and horny plant-like polypidom, the axis of which is filled with living pith and the branches studded with little cups or cells in which are seen the fleshy polypes, each a stomach with arms around its mouth for the seizing of its food. Each of these polypes is an individual distinct in itself and acting for itself, yet, besides that individual life, sharing in the common existence of the whole and obeying in reference to its brethren the laws which determine the cha¬ racters of the species—the constant form and arrangement of the parts of the whole. If the axis should perish all the polypes must perish, but one or several polypes may perish without affect¬ ing the others or the life of the axis. Now all such polypes are true nutritive individuals, devoted to the service of the composite individual or zoophyte of which the polypidom is as it were the bark. The zoophyte begins as a single individual, as the plant begins as a single phyton : polype after polype is built up and shares in the common interest with that first individual, as leaf after leaf is formed to serve in the same commonwealth with the first phyton. The normal type of the zoophyte is a simple stomach, that of the plant is a simple gill. At certain periods in the life of the zoophyte there appear pro¬ jecting from the axis or springing from its branches variously formed bodies, usually very dissimilar from the other parts of the whole, in which the ova are after a time formed. These have been called “ vesicles,^ and many opinions have been entertained re¬ specting their nature and origin. By most naturalists they have been styled evolutions from the pith or fleshy axis *. They have been termed expansions of the stem f. Some have considered them female individuals J or polypes of a different kind from the rest, inclosed in a larger cell §, and by some the vague term of ovariform buds has been applied to them ||. Now if the parallel we have drawn so far between the plant and the zoophyte be carried out, these so-called “ ovigerous vesicles ” should be essentially either single individuals ideally metamorphosed into reproductive organs comparable to the mo- nocarpous germens of plants, or a series of individuals joined to- * Johnston, Grant. f Carpenter. J Ehrenberg, Loven. § Carpenter. |] Blainville.