The metabolism of amino‐acids by Paramecium caudatum

Abstract

AbstractThe object of the present study is to determine by quantitative means the rate at which a given number of paramecia can utilize the various amino‐acids and to study factors influencing this rate.The method consisted in testing the rate of utilization of isolated and mixtures of amino‐acids by a known number of Paramecium caudatum. The amino‐acids were used in 0.1 per cent solution and were tested, by the Henriques‐Sörensen formol titration method for amino‐acids, at the beginning and after the paramecia had lived in these amino‐acids for twelve hours. The difference between these two tests, figured in percentage, is considered as the amount utilized by the paramecia. The part played by bacteria was found to be negligible when isolated amino‐acids were studied. The influence of temperature on the rate of utilization of the amino‐acids has been studied, and the results show a direct relationship between the two.The rate of utilization was decreased by anaesthetics and nitroglycerin. A careful study has been made of a number of isolated amino‐acids and the rate of utilization of each discussed in relationship to the others studied. An explanation of why one amino‐acid was used more than another amino‐acid was sought for, but not found. A detailed discussion of the above points has been presented in the body of the paper.