The growth kinetics of Neurospora in unstirred liquid culture may be accounted for by an exponential and a linear growth phase. If a cubic growth phase exists it is in addition to the exponential and linear phases of growth. A method of measuring the exponential doubling time in unstirred cultures is described which may be usefully applied to fungi which cannot be observed growing exponentially by normal methods. Rate of linear growth is shown to be proportional to the surface area of the culture. Expression of linear growth rates as [mu]g. /cm. 2hr would assist in the comparison of data from different laboratories.