Abstract
IN the January number of the Quarterly Journal of Microscopical Science, Mr. E. A. Minchin gives a valuable addition to our knowledge of asconid sponge morphology in a paper on the origin and growth of the triradiate and quadriradiate spicules in the family Clathrinidæ. Mr. Minchin here produces full histological evidence of his discovery of the composite origin of these two kinds of spicules; he shows that the triradiate spicules are formed by trios of dermal cells which immigrate from the epithelium to the interior; by the division of each cell a sextet is formed, and the spicule appears with each of its rays corresponding to two sister cells of the sextet. With regard to the quadriradiate spicules the three basal rays develop exactly as do the triradiate spicules, but the fourth or gastral ray is secreted by a mother cell derived from a porocyte. The spicules are crysstalline as a whole, but the rays are non-crystalline so long as they are distinct from one another, and may remain so for some little time after union has taken place; the crystallisation appears to start from the secondary deposit which unites the rays at the centre. Much skill and care have been bestowed on the beautiful drawings illustrating these researches, and they are admirably reproduced in an excellent series of plates.—Prof. MacBride, in a paper on the early development of Amphioxus, shows the similarity between the cœlomic chambers of Amphioxus and Balanoglossus, and homologises the metapleural lymph canals of the former with portions of the collar pouches of the latter; in consequence of this he revives Bateson's comparison of the atrial folds of Amphioxus with the posterior collar folds of Balanoglossus.—Mr. Shipley gives an account of a new Tapeworm from a bird in the Sandwich Islands.—Dr. Willey gives the diagnosis of a new genus of Enteropneusta.—Prof. Haswell describes a Turbellarian from deep wells in New Zealand.—Prof. Ray Lankester, in a note on the development of the atrial chamber of Amphioxus, corrects Prof. MacBride's statements with regard to the well-known researches by himself and Dr. Willey on the development of the atrial chamber.
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Scientific Serials. Nature 57, 475–476 (1898). https://doi.org/10.1038/057475b0
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DOI: https://doi.org/10.1038/057475b0