Societies and Academies

Abstract

LONDON. Royal Society, Mar. 12.-E. W. Fish: On the reaction of the dental pulp to peripheral injury of the dentine. A series of earlier experiments in which diffusible dyes were placed in the pulps of human teeth indicated that when primary dentine is injured at the periphery either by caries or attrition, the whole tract of affected tubules dies and becomes walled off from the pulp by secondary dentine. The nature of the reaction is found to vary with the severity of the lesion. The usual result is that the pulp ends of the injured tubules are sealed off by a deposit of calcium salts, and this is followed by a deposit of secondary dentine.-E. B. R. Prideaux: The combination curves, hydrogen ion regulating power, and dissociation constants of gelatin. The properties of gelatin as an ampholyte have been deduced from the combination curves, in which pJL is expressed as a function of added acid or alkali. Considerable differences were noted between the combination curve of gelatin and those of ammo acids. By means of equations which express the simultaneous relations: (a) absence of inflection at the isoelectric point, (6) the existence of the iso-electric condition; the constants of the basic and acidic dissociations have been calculated on the assumptions that gelatin consists mainly (i) of un-dissociated molecules, (ii) of amphoteric ions at its isoelectric point. On either theory, three constants are obtained, of which one acidic and one basic constant are nearly equal to one another.-R. Snow: Experiments on growth and inhibition. Since it had been found previously (New Phytologist, vol. 28, p. 345; 1929) that in older and taller pea seedlings the young leaves near the apex inhibit the axillary buds near the base of the stem more strongly than in very young short seedlings, experiments were carried out to test whether the increase in strength of inhibition is due to the greater length of intervening stem. It is concluded that the strength of inhibition increases with increasing length of intervening stem. Axillary buds normally grow to a certain length before they are stopped by inhibition, and they are susceptible to inhibition during their early growth as well as later. The interpretation of the increase of inhibition is briefly discussed.-C. H. Lea: The effect of light on the oxidation of fats. A quantitative iodimetric method for estimation of the peroxide oxygen present in rancid fats is described. By this means it is possible to follow the atmospheric oxidation of pure fats or of animal fats in the tissue, and, in conjunction with a suitable source of light, to forecast the relative susceptibilities of fats to oxidation. This method, with a quantitative modification of the Kreis test, has been used to investigate the effect on the oxidation of fats.-H. Munro Fox and H. Ramage: A spectro-graphio analysis of animal tissues. Tissues of annelids, molluscs, man, and some other animals have been studied. Iron and copper were present in all kinds of protoplasm investigated. Manganese was widely distributed. The manganese content of tissues varies with the locality in which a given species of animal lives. Nickel and cobalt occurred spasmodically, the former being more frequent. Except in one case, all high concentrations of nickel were accompanied by cobalt. In one tissue only did cobalt occur without detectable nickel. Lead and silver both exhibit an irregular distribution (see also NATCJBE, Nov. 1, 1930, p. 682).-A. S. Parkes: The reproductive processes of certain mammals (1). Cricetulus failed to breed under laboratory conditions, but it was found possible to investigate the cyclic changes occurring in the non-pregnant females, about half of which possessed perfectly normal.reproductive organs. The cycle is very similar to that of the mouse. Cortiincation of the vaginal epithelium, diagnosed in the live animal by examination of the vaginal contents, was found to be associated with the period of ovulation. The average length of cycle was a little under five days, and the average number of follicles maturing at one period of ovulation was eight.-F. G. Spear: The delayed lethal effect of radium on tissue cultures in, vitro-comparison of continuous and spaced radiation. It was found to be immaterial whether the radiation was given in one dose of six hours or in six fractional doses of 60 minutes each at 24 hourly intervals.