It has also frequently been pointed out that acid and water-logged soils are richer in fungus content than normal agricultural soils. On the other hand, Brown and Halversen[2] found, examining six plots receiving different treatment and studied through a complete year, that the numbers of fungi were unaffected by moisture, temperature, or soil treatment. Against this, however, must be set the work of Coleman[3] who studied the activities of fungi in sterile soils and found such factors as temperature, aeration and food supply to exercise a deciding control. Investigations at Rothamsted show that Broadbalk plot 13, receiving double ammonium salts, superphosphate and sulphate of potash and yielding 31 bushels per acre, and plot 2, receiving farmyard manure and yielding 35·2 bushels, contain approximately equal numbers of fungi. This figure is about half as high again as that for plot 3, which is unmanured and yields 12·6 bushels, plot 10, with double ammonium salts alone and yielding 20 bushels, and plot 11, with double ammonium salts and superphosphate and yielding 22·9 bushels per acre. A primary factor, however, in all considerations such as these is the equality of distribution of fungi laterally in any particular soil. There are probably few soils so homogeneous as the Broadbalk plots at Rothamsted, and on plot 2 (farmyard manure since 1852) samples taken from the lower and upper ends and the middle region gave average numbers of colonies per plate of 24, 23, and 25 respectively. On the other hand, soil samples taken only a few yards apart in the middle region of the plot gave average plate counts of 33·7 and 56·8. CONCLUSION.