much of the anion had been adsorbed by the cell. It was then assumed that the kation had been adsorbed in equivalent measure, which would not be exactly correct; the difference, however, would not constitute a serious error in the magnitudes obtained. Chlorine determinations were made by direct titration of 25 cc. of the liquid with AgNO, 0.01M. Since deviations in the concentration of the salt solutions played small part in the adsorption no great care was exercised in making them up, but the chlorine was titrated in the originals and then at the close of the experiment. The results are expressed in cc. of the silver nitrate necessary to effect the titration. Table X. gives results from agar-pectin-gelatine-lecithin cells; 3 parts of gelatine to 5 parts of agar were used in the plasmatic layer.10 A set of agar-gelatine-pectin cells with lecithin omitted with contents of 20 per cent. sugar solution gave the following: I am indebted to Professor J. W. E. Glattfeld, of the University of Chicago, for the titrations. 10 19 See Gortner, R. A., and Hoffman, W. F., “Quantitative Estimation of Chlorides and Sulphates in Expressed Plant Tissue Fluids," Botan. Gazette, 77, 96, 1924, for additional methods. The rate of endosmose formed the series Na < K < Ca in both concentrations of the immersion solution. The rates of absorption of chlorine from the solutions of the higher concentration formed the series K > Na > and > Ca. The rate from the weaker solution formed the series Ca > Na > and > K, a reversal of the action of Ca and K which may be due to some unknown features of the cell. Another set gave the following data (agar-gelatine-pectin-lecithin cells): The permeability series of these cells was NaCl > Seawater > KC1 > CaCl2. The amounts of chlorine adsorbed formed the series KCl > NaCl > Seawater > CaCl2. The adsorption of chlorine was seen to be very much greater in the alkaline solution than from the acid-salt solution. The influence of the concentration of the cell-contents on absorption was noticeable in potassium only, which was probably due to faulty operation, or some defect in the cells. The average absorption of chlorine by the cells with 20 per cent. sugar solution was 18.3 while it was 17.3 for the cells containing only 0.5 per cent. sugar solution, a difference largely due to the discordant action of the cells in the potassium solution. A similar discrepancy in the action of cells was found in the sodium solution in the following series. In this series the adsorption of the salt was much greater from alkaline than from neutral solutions, and the adsorption of K much greater than that of Na. It is also seen that the adsorption of ions by the colloidal cell was but little influenced by the concentration of the cell-contents; the average loss of chlorine from all immersions of cells with concentrated contents was 35.3 per cent.; to cells with dilute contents it was 34.5 per cent. While the current conceptions of the physical action of the cell make it obvious that the passage of electrolytes into the cell-material is affected very little by the osmotic potential of the cell-contents, this conclusion has not been directly or adequately tested. The foregoing tests show that the adsorption of chlorides by constructed cells with dilute contents was but slightly different in amount from the adsorption by similar cells with concentrated contents. The average adsorption of chlorides from neutral and alkaline salts in one series by cells with a 20 per cent. sap was 18.3 per cent. of the immersion, while 17.3 per cent. was taken up by cells with contents of 0.6 per cent. sugar solution. In another series cells with the more concentrated sap took up 35.3 per cent. of the chlorides while those with the dilute contents adsorbed 34.5 per cent. The relative amounts of the various salts which may be taken up vary with the composition of the cell and other controllable factors. The well-known acceleration of adsorption in solutions made alkaline is strikingly exemplified. DEPT. BOTANICAL RESEARCH, CARNEGIE INSTITUTION. THE FAUNAS OF THE CONCRETIONARY ZONES OF THE OREODON BEDS, WHITE RIVER OLIGOCENE.1 I. INTRODUCTION AND SUMMARY. When the Princeton 1920 Expedition to South Dakota was being planned, I hoped that we might succeed in locating one or more zones or levels in the White River beds, of wide areal extent and rich fossil possibilities, which would afford large assemblages of con 1Investigation aided by a grant from the Marsh Fund of the National Academy of Sciences. |