Includes bibliographies.

The soil system, by A. Burges.--Bacteria in soil, by F. E. Clark--Fungi in soil, by J. H. Warcup.--The actinomycetes, by E. Kuster.--Soil algae, by J. W. G. Lund.--Protozoa, by J. D. Stout and O. W. Heal.--Nematoda, by C. O. Nielsen.--The enchytraeidae, by F. B. O'Connor.--Lumbricidae, by J. E. Satchell.--Arthropoda (except acari and collembola) by F. Raw.--Acari, by J. A. Wallwork.--Collembola, by W. G. Hale.--Mollusca, by P. F. Newell.--The importance of antibiotics and inhibiting substances, by D. Park.--Soil micro-organisms and plant roots, by D. Parkinson.--The decomposition of organic matter in the soil, by A. Burges.--Soil micro-organisms and plant protection chemicals, by N. Walker.