Abstract
The Quarterly Journal of Microscopical Science, November.—On Julinia, a new genus of compound ascidians from the Antarctic Ocean, by W. T. Calman (plates 1-3). The colony is described as irregularly cylindrical in shape, measuring 78˙5 cm. in length, and from 1˙5 to 2˙5 cm. in diameter; it was found floating on the surface of the sea in the north of Erebus and Terror Gulf; a considerable quantity was seen; no attaching fibres were found, but it was probably an attached form. The species is described as Julinia australis, and it is provisionally placed in the Distomidse.—Hermaphroditism in mollusca, by Dr. Paul Pelseneer (Ghent) (plates 4-6). Hermaphroditism is found in the Amphineura, the Gastropoda, and the Lamellibranchia. It is not self-sufficient, is sometimes protandric; it would seem to the author to be not a primitive arrangement, but to be derived from the unisexual state, and to have been established upon the female organism.—Description of the cerebial convolutions of the chimpanzee known as “Sally,” with notes on the convolutions of the brains of other chimpanzees and of two orangs, by W. Blaxland Benham (plates 7-11).—On the inadequacy of the cellular theory of development and on the early development of nerves, particularly of the third nerve and of the sympathetic, in Elasmobranchii, by Adam Sedgwick, F.R.S. More than ten years ago the author called attention to the inadequacy of the cellular theory of development: “Embryonic development can no longer be looked upon as being essentially the formation by fission of a number of units from a single primitive unit, and the coordination and modification of these units into a harmonious whole. But it must rather be regarded as a multiplication of nuclei and a specialisation of tracis and vacuoles in a continuous mass of vacuolated protoplasm.” And “although opinions have changed on this important subject, and although there are some who think that they have escaped fiom the domination of this fetish of their predecessors, yet as a matter of fact the cellular theory of development is still rampant, still blinds men's eyes to the most patent facts, and still obstructs the way of real progress in the knowledge of structure.” When a student begins his zoology he is told that “the various structures present in a protozoon are all parts of one cell, whereas in a metazoon the various parts are composed of groups of cells which differ from one another in structure.” When in a later period of his studies he begins embryology, “the importance and distinctness of the cell meets him at every step, from the complete cleavage which he is led to believe is primitive, to the development of nerves according to the views of His.” If we take the so-called mesenchjme tissue of elasmobranch embryos, it is described as consisting of “branched cells lying between the ecto- and the endo-derm,” while, as a matter of fact, “the separate cells have no existence,” but “there is a ieticulum of a pale non-staining substance holding nuclei at its nodes. And far from the development of nerves being an outgrowth of cell-processes from certain central cells, it is simply a differentiation of a substance which was already in position.” This important memoir is so condensed as to make it extremely difficult to condense it further, but enough has been given to indicate its nature.—On Benhamia cœifera, n. sp., from the Gold Coast, by W. B. Benham (plate 12). This large species (20 inches) was found at Axini in the Fantee country, on the west coast of Africa.
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Scientific Serial. Nature 51, 213 (1894). https://doi.org/10.1038/051213a0
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DOI: https://doi.org/10.1038/051213a0