The third disease-producing microbe found naturally in soil is that which produces the disease known as Malignant Œdema. Pasteur called this _gangrenous septicœmia_. Unlike quarter evil, malignant œdema may occur in man in cases where wounds have become septic. Animals become inoculated with this bacillus from the surface of soil, straw-dust, upper layers of garden-earth, or decomposing animal and vegetable matter. The bacillus occurs in the blood and tissues as a long thread, composed of slender segments of irregular length. It is motile and anaërobic. The spores are larger than the diameter of the bacillus, and the organism produces gas; so much is this the case in artificial culture, that the medium itself is frequently split up. Both malignant œdema and symptomatic anthrax are similar in some respects to anthrax itself. There are, however, a number of points for differential diagnosis. The enlargement of the spleen, the non-motility of the bacillus, the enormous numbers of bacilli throughout the body, the square ends, equal inter-bacillary spaces, aërobic growth, and characteristic staining afford ample evidence of anthrax. _The Relation of Soil generally to certain Bacterial Diseases._ Recent investigations have, in effect, considerably added to our knowledge of pathogenic germs in soil; and whilst the three species enumerated above are still considered as types normally present in soil, it must not be forgotten that other virulent disease producers either live in the soil or are greatly influenced by its conditions. Fränkel and Pasteur have both demonstrated the possible presence of anthrax. Fränkel maintained that it could not live there long, and at ten feet below the surface no growth occurred. This may have been due to the low temperature of such a depth. Pasteur held that earthworms are responsible for conveying the spores of anthrax from buried carcasses to the surface, and thus bringing about reinfection. Cholera, too, has been successfully grown in soil, except during winter. The presence of common saprophytes in the soil is prejudicial to the development of the cholera spirillum, and under ordinary circumstances it succumbs in the struggle for existence. From experiments recently conducted for the Local Government Board by Dr. Sidney Martin, evidence is forthcoming in support of the view that the bacillus of typhoid can live in certain soils. Samples of soil polluted with organic matter formed a favourable environment for living bacilli of typhoid for 456 days, whereas in sterilised soil, without organic matter, these organisms lived only twenty-three days. Tubercle also has been kept alive for several weeks in soil.