HORIZONTAI. DIFFUSION Values for C and in calculated from various spore-dispersal tests are shown in Table VIII. Evidently for microbiological work we must use high values of perhaps because we are concerned with longer sampling periods than Sutton. We shall therefore choose C,, = o•8 (metre)t, and = (metre) , as standard in Chapter XIII where deposition gradients are considered in detail. There seems to be little in favour, however, of adopting In = 2•o instead of in = I•75.