Studies in Microorganismal Behavior by Computerized Television

Abstract

Up to the present time behavior of motile microorganisms has been investigated in general by two methods. (1) “The mass movement” method and (2) the “individual cell” method. Quantitative “mass movement” techniques involve the principle of the measurement of optical density of cell suspensions (vide Pohl, 1948; Bruce and Pittendrigh, 1956; Feinleib and Curry,1967, etc.) As is well known, this method records changes in optical density resulting from the movement of cells into or out of the point being “watched”. This is a good method to make measurements of the responses of populations of cells to changes in the environment (for example, studies of vertical or horizontal migration in gradients.) But the method is obviously not well suited to investigate the movement of the individual cell or to find out how such movements bring about the accumulation or dispersal that may be observed. A further weakness in the system results from the fact that mass movement takes time and this means that the observer may be monitoring movements of cells which are undergoing a change in physiological state when, indeed, he should be investigating them as nearly as possible in the steady state.