No comparative estimations have been made of the number of fungi in the soils of different regions. There are, however, certain figures which show that decided seasonal differences exist. Thus, correcting and averaging certain of Waksman’s results[25] the following numbers of fungi per gram of soil at 4 inches deep are obtained; September, 768,000; October, 522,000; November, 310,000; January, 182,000. At Rothamsted results have been obtained which would appear to mark a clear seasonal rhythm, corresponding in the time of its maxima in Autumn and Spring with the periodicities known for many other ecological communities (Fig. 19). The numbers of fungi at various depths in the soil show very clearly marked differences. The distribution in the top 4-6 inches depending probably upon the depth of soil, is more or less equal, but there is a very rapid falling off in numbers, especially between 5-9 inches, until at 20-30 inches fungi are either very few in number or absent. Thus Takahashi[22] found 590,000 fungi per gram at a depth of 2 cms. and only 160,000 at 8 cms. TABLE XIII.--INFLUENCE OF SOIL TREATMENT UPON THE NUMBERS OF FUNGI AS DETERMINED BY THE PLATE METHOD--(AFTER WAKSMAN). +--------------------------+---------+-----------------+ | | |Numbers of Fungi | | Soil Fertilisation. |Reaction.|per Gram of Soil.| +--------------------------+---------+-----------------+ | | P.H. | | |Minerals only | 5·6 | 37,300 | |Heavily manured | 5·8 | 73,000 | |Sodium nitrate | 5·8 | 46,000 | |Ammonium sulphate | 4·0 | 110,000 | |Minerals and lime | 6·6 | 26,200 | |Ammonium sulphate and lime| 6·2 | 39,100 | +--------------------------+---------+-----------------+ The type of soil and its treatment exercise a great influence over the number of fungi present. Fischer[6] found that farmyard manure increased the number of fungi in uncultivated “Hochmoor,” cultivated “Grunlandmoor,” and a clay soil by two, three, and five times respectively. Waksman’s results[25] indicate that the more fertile soils contain more fungi, both in number and species, than the less fertile ones, and if one averages his results, the following figures are obtained: garden soil, 525,000 per gram; orchard soil, 250,000; meadow soil, 750,000; and forest soil, 151,000. Recently Waksman[25_e_] has found that manure and acid fertilisers increase the numbers of fungi in the soil, whereas the addition of lime decreases them (Table XIII.). Jones and Murdock[10] examined surface and sub-surface samples of forty-six soils representing seventeen soil types in eastern Ontario. Molds were fairly uniform in numbers in all soils except a sandy clay loam and sandy clay shale, in which they were absent.