ABSTRACT
The effect of temperature has been studied more than that of any other single ecological factor, and its significance for the growth of populations of many species has been known for a considerable period. Previous studies on Protozoa have been confined to the effect of temperature on the rate of division, and so far as is known other aspects of the problem have not as yet been examined. Thus,Woodruff & Baitsell (1911) and Mitchell (1929) examined the effect of temperature on the division rate of Paramecium in cultures containing bacteria. This effect was also studied on Chilomonas paramecium in isolation cultures by Smith (1940),and on Tetrahymena geleii by Phelps (1946). Phelps observed division rates only in the logarithmic phase of growth, and in that work he was not concerned with the effect of temperature on population growth. It seemed worthwhile, therefore, to examine the effect of temperature on the growth of Chilomonas paramecium in greater detail.
Standard deviation is calculated from the formula 
