Societies and Academies

Abstract

LONDON. Royal Society, February 12.—H. Muir Evans: A contribution to the anatomy and physiology of the air-bladder and Weberian ossicles in Cyprinidse. In Cyprinida? the air-bladder is constricted, so as to form an anterior and posterior chamber connected by a short duct. The Weberian mechanism is designed to conduct vibrations and not to register variations of pressure. The nerve-ganglion regulates tension of anterior sac and thus allows it to receive vibrations: it controls the sphincters and prevents undue lowering of tension when the pneumatic duct is open, and excess of tension due to pressure of gas in the posterior sac.- J. S. Huxley: Studies on amphibian metamorphosis. II. It is not always possible to induce metamorphosis of the axolotl by enforced air-breathing in a con siderable number of specimens. This may be due to genetic differences between strains. When axolotls are so treated the dorsal fin falls over and fuses completely with the skin of the back. By using urethane it was found possible to keep frog tadpoles in narcosis for 8-12 days. If previously treated with thyroid, they metamorphosed as rapidly as controls. An atmosphere of oxygen is deleterious to tadpoles, and retards metamorphosis. A mixture of air and oxygen containing 40 per cent, oxygen allows meta morphosis to proceed at the same rate as in air. The dorsal fin of male newts which is developed in the breeding season is not caused to regress by administra tion of thyroid, unlike the larval fin-crest occupying the same position.-A. S. Parkes and J. C. Drummond: Effects of vitamin-B deficiency on reproduction. In a buck rat on a diet totally deficient in vitamin-B degeneration of testes and sterility ensue. The amount of degeneration can be generally correlated both with degree of deficiency and time on the diet. The fecundating power of the buck can be definitely correlated with degree of deficiency. Size of litter, however, shows little variation. The proportion of males among the young decreases.-A. Dendy: On an orthogenetic. series of growth forms in certain tetraxonid sponge-spicules. The so-called strept-asters or siliceous spicules of the Theneidae and Pachastrellidae are not asters, and the spirally twisted axis which they exhibit is not an elongated centrum. They are really derivatives of the primitive triact, which have arisen in accordance with a remarkable law of growth. These spicules, for which the name "dichotriacts "is proposed, appear to form an orthogenetic series of growth-forms, probably re presenting both a phylogenetic and an ontogenetic series. As in true asters, the increase in the number of rays is accompanied by diminution in size.-C. E. Walker: The meiotic phase in Triton (Molge vulgaris). As is the case in the ordinary somatic mitoses, the univalent filament splits in the telophase of the somatic division immediately preceding the 1st meiotic (heterotype) division. These semivalent threads rejoin in the early prophase; the univalent filaments thus formed join longitudinally, and at the anaphase whole somatic chromosomes are distributed to the daughter cells. The splitting of the univalent filament in the telophase of the last somatic division is not consummated until the 2nd meiotic division, when the chromosomes split into longitudinal halves. The 1st meiotic division is a unique phenomenon interpolated between two mitoses providing for the equal distribution of whole chromosomes.-W. E. Alkins: Clausilia bidentata (Strom) and Cl. cravenensis (Taylor): a statistical inquiry into the relationship of two similar species. Clausilia bidentata is widely spread in Britain and elsewhere; Cl. cravenensis occurs only in a restricted area in the north of England, and its specific status has generally been questioned. The altitude, diameter, and diameter/altitude ratio in series of each species collected from limited loci in which both species live together in the same habitat, have been studied. While both species, and especially bidentata, are highly variable, and though local races may be distinguished within cravenensis, the two forms are clearly separated by biometric criteria, and there is no evidence of intermediate forms.