Quantitative studies on the flicker phenomenon in the erythrocytes.

in the erythrocytes is difficult to describe or to define. It is well known that the normal erythrocyte has the shape of a biconcave disk with a pale center and, when living, exhibits two different activities: first, vibratory variations of density inside the cytoplasm, best visible at the junction of the outer dark and the pale central regions; second, slow undulating movements of the membrane resulting in the formation of irregular bulges which appear and disappear by intervals. The flicker phenomenon was first described in 1890 by Browicz,1 using ordinary light microscopy. In 1901, Cabot2 confirmed this observation. In 1949 Pulvertaft3 described the flicker as seen with phase-contrast micro-scopy which makes it very prominent. According to this author, the phenomenon is present in mammalian, avian and amphibian erythrocytes; it is also present in reticulocytes, abnormally shaped anemic erythrocytes, in erythroblasts, but not in proerythroblasts, nor in " ghost " cells. Pulvertaft mentions that fluorides inhibit the flicker in normal cells and suggests that this phenomenon may be related to glycolysis. In 1950, Blowers et al.5 made an extensive study of this problem; they found that the flicker is inhibited in the presence of fluorides and mono-iodo acetate, but persists in the presence of carbon monoxide, cyanide and azide. They concluded that it is related to glycolysis but not to respiration. Parpart and Hoffman5 in 1956 contradicted these conclusions entirely. According to these authors, the flicker phenomenon is simply the result of Brownian motion. In order to clarify these discrepancies , it seemed important-as an initial study-to obtain quantitative records of the phenomenon permitting measurement of its frequency. According to the literature, only few attempts have been made in the past to quantitate the flicker. Technics which have been used include cinematographic recording,#{176} stroboscopy3 and television microscopy,5 but none of these experiments have been successful. We assumed that the best way of recording and eventually quantitating