Journal of the New-York Microscopical Society (Volume 4) (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated.1888 Excerpt: ... Journal OF THE NEW-YORK MICROSCOPICAL SOCIETY, Vol. IV. JULY, isae. No. 3. NOTES ON THE THREAD-CELLS OF CERTAIN CCE-LENTERATE ANIMALS. BY CHARLES F. COX. (Read March 2oT, 1888.) Thread-cells, lasso-cells, filiferous capsules, urticating organs, cnidae, or nematocysts, as they are variously called, are usually set down as characteristic of the whole sub-kingdom Coelenterata, although their existence has not been actually demonstrated in every order of either the Hydrozoa, or the Actinozoa. Nor is it certain that they are confined to coalenterate animals. Prof. Allman claims to have observed the emission of urticating filaments by a species of Bursaria, and there is reason to believe that they occur in other infusoria, and perhaps in some annelids. They have been reported to exist likewise in certain naked mollusks, though it is still a disputed question whether in such cases they are not derived from ccelenterate animals upon which the mollusks feed. In general, however, they may be said to be the peculiar property of tentacled animals, and there is good evidence upon which to regard them as organs of offence and defence. When matured and fitted for their special function, these organs' are situated in the outer layer, or ectoderm, and are Explanation of Plate 19, Fios. III., IV. and V., are process reproductions of photographs from nature; Fig. III. showing the cell with the thread partially emitted, Fig. IV. the fully extended thread, and Fig. V. two empty cells with the clear spaces at the bases of the attached threads. Fios. I. and II., are modifications of Fig. III., made as diagrammatic representations of the cell before and at the beginning of the extrusion of the thread. usually collected into reniform groups, or knobs. They are, however, found, in v...