Abstract
LONDON. Royal Society, February 2.—Sir Charles Sherrington, president, in the chair.—C. Shearer; The oxidation processes of the echinoderm egg during fertilisation. The oxygen consumption and the carbon dioxide output of the eggs of the sea-urchin E. microtuberculatus during fertilisation have been measured by means of a special form of the Barcroft differential manometer. An immediate consumption of oxygen and a corresponding output of carbon dioxide take place on the sperm being added to the eggs. At the end of one minute this increase is equivalent to a rise in the metabolic rate of the egg of more than 8000 per cent. Sections of fixed material preserved during different intervals of the process of fertilisation show that this is brought about by the contact of the sperm with the external surface of the egg-membrane. The fusion of the male and female pronuclei in the later phases of fertilisation is without any influence on the curve of the oxygen consumption. The dipeptide glutathione is present in both ripe germ-cells of the sea-urchin E. miliaris, but one minute after fertilisation it is found in much greater quantity in the egg in reduced form, and evidence shows that it plays a very important, if not the chief, part in the oxidation processes taking place.—J. Schmidt: The breeding-places of the eel. The common or fresh-water eel (Anguilla. anguilla or A. vulgaris) of Europe has only one breeding area, as determined by the distribution of the larvæ, situated in the western Atlantic, south-east of Bermuda. The larvae are pelagic, and are carried to the east and north-east by the Atlantic current; their growth and the metamorphosis into the “elver,” or young eel, are described; the elvers are three years old. The breeding area of the American eel (A. chrysypa) is south-west of that of the European eel, but overlaps it; in the American eel growth of the larvæ is much more rapid than in the European species, and the elvers are only one year old. This explains why the European eel is not found in American rivers or the American eel in Europe; if larvae of the American eel are carried eastwards, the metamorphosis takes place in the middle of the Atlantic; if larvae of the European eel go north or north-west, they reach the American coast two years before the metamorphosis is due.—J. Gray: The mechanism of ciliary movement. Pts. 1 and 2. The rate of beat of the cilia on the gills of Olytilus edulis can be controlled by adjusting the hydrogen-ion concentration of the cell inferior. The amplitude of the beat can be controlled by an alteration in the osmotic pressure of the external medium. The cilium is essentially a bundle of elastic fibres the tension of which varies during the different phases of the beat. The activity of cilia and muscle-cells depends on similar conditions and mechanisms. The normal properties of the cell-membrane are maintained only in the presence of divalent cations. Ciliated cells are permeable to monovalent cations, but not to anions. Ciliary activity may persist when the normal semi-permeable properties of the cell-wall have been destroyed—J. S. Huxley and L. T. Hogben: Experiments on amphibian metamorphosis and pigment responses in relation to internal secretions. Sala-mandra and Triton larvae may be metamorphosed by immersion in a dilute solution of iodine. Metamorphosis is retarded by low temperature; high temperature at first, causes increased growth of the gills. Sexually mature Axolotls can be made to undergo rapid metamorphosis by means of a thyroid diet. Metamorphosis is accompanied by exophthalmos, apparently in all Amphibia. Iodine free of organic combination, and fresh glandular substance of the prostate and pituitary anterior lobe, are without effect on the metamorphosis of the Axolotl. Pituitary feeding produces a marked temporary dilatation, followed by excessive contraction of the dermal melano-phores in albino Axolotls. Adrenal medulla extract produces, temporarily, complete contraction of the dermal melanophores in the Axolotl. Pineal administration rapidly causes a striking transient contraction of the dermal melanophores in frog tadpoles, but has no effect on the melanophores of the Axolotl. Seven months' thyroid feeding was not accompanied by any noteworthy somatic changes in Necterus.
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Societies and Academies. Nature 109, 193–194 (1922). https://doi.org/10.1038/109193a0
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DOI: https://doi.org/10.1038/109193a0