On the Nematocysts of AEolids . creted; the cnidoblast itself is drawn away from this pointtowards the lumen of the cnidosac, and does not apparently take partin the secretion of the cyst, but in the meantime ingests nematocystsat its opposite end, which remains naked and amoeboid. When sufficientnematocysts have been ingested and arranged by the cnidoblast, themembranous cyst is completed, the nuclei of the intermediate cellsmoving up between the cnidoblasts about half way towards the lumen 1903.] On the Nematocysts of J^olids, 483 of the cnidosac. When the cyst is completed both the cnidobla
On the Nematocysts of AEolids . creted; the cnidoblast itself is drawn away from this pointtowards the lumen of the cnidosac, and does not apparently take partin the secretion of the cyst, but in the meantime ingests nematocystsat its opposite end, which remains naked and amoeboid. When sufficientnematocysts have been ingested and arranged by the cnidoblast, themembranous cyst is completed, the nuclei of the intermediate cellsmoving up between the cnidoblasts about half way towards the lumen 1903.] On the Nematocysts of J^olids, 483 of the cnidosac. When the cyst is completed both the cnidoblast andthe associated intermediate cells undergo degeneration, so that in theolder parts of the cnidosac each cnidocyst consists simply of amembranous bag, containing nematocysts, which are often apparentlyattached to its inner wall to keep them in place, and - a more or lessdegenerate cnidoblast; while wedged between adjacent cnidocysts arefound small darkly staining bodies, the remains of the intermediatecells {^g. 13). }Jem.^ ^-NemJ- Summary. The facts brought forward as evidence that the nematocysts of -Solidsare derived from their prey are as follows :— 1. Not only are nematocysts of ^Slolids and Coelenterates identical in plan of construction and mode of discharge, but each of severaldistinct types occurs in both groups. 2. A single type of nematocyst does not occur uniformly throughout a species, but different individuals of the^same species may havequite different nematocysts; moreover, a single individual mayhave nematocysts of several different types, found in as manydistinct species or groups of Coelenterates. 3. When it is known on what Coelenterate an ^olid has recently been feeding, the nematocysts of the bwo are found to be 484 Mr. G. H. Grosvenor. [Nov. 3, identical. Also the nematocysts from the faeces of an ^olidywhich are generally admitted to be derived from their food, arealways identical with at least some of the nematocysts from thecnidosacs. 4.
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