The results are given of an examination of 128 different soils from 30 different localities of cultivated and virgin land of Manitoba, made during the months of October, 1933 to June, 1934. The results are based upon the microscopic observations of the 128 soils and of cultures of them, during a period of two months each; also upon chemical tests of these soils. An attempt has been made, firstly to determine which species constitute the protozoan fauna of Manitoba soils, and the extent to which variations in soil type and soil texture cause changes in this fauna; secondly, to detect the influence of such factors as hydrogen ion concentration, soil depth and variations in amount of precipitation upon the kind and abundance of protozoa; thirdly to determine the effects of various natural and artificial fertilizers applied to soils on Manitoba Agricultural College farm plots. Thirty species of protozoa were identified. None of the Actinopoda, Testaceous Rhizopoda, Cryptonionadinae nor Hetero- and Oligo-tricha were found. In every soil tested the hydrogen ion concentration decreased with increase in depth. Also the protozoan population decreased with increase in depth and was absent at 36 inches...