THE catastrophic inundation of the valley of the River Ohio, which was referred to in NATURE of January 30 (p. 185), has since assumed even more alarming proportions and threatens to overwhelm in a comprehensive deluge the whole of the Mississippi Valley from the town of Cairo (Illinois) at the junction with the Ohio River right down to the Gulf of Mexico. The flood waters from the latter river are moving onwards, unchecked and uncontrolled, at the rate of 80-90 miles per twenty-four hours. The extent of country involved can be seen from the accompanying map. At the moment of writing, Cairo is just commencing to receive the crest of the wave, which is expected to culminate in a level of 62 ft. Thence it will pass on through Memphis (Tennessee), Vicksburg and Natchez (Mississippi) to Baton Rouge and New Orleans (Louisiana). In the Ohio Valley there has been left a track of widespread ruin and desolation, with the water still standing 12 ft. deep in the streets of Evansville, just below Louisville. Surveying the disaster at the week-end, the American Red Cross reported 400 people dead, 800,000 homes flooded, more than a million people still homeless and more than a quarter of a million marooned in the upper floors and roofs of their houses or other refuges. The chairman stated with every justification that the American nation is faced with the gravest emergency since the Great War. The material damage is estimated at 400 million dollars (£80,000,000). Not less important is the denudation of the valley, from which some 3,000,000 tons of fertile soil have been swept down-stream by the force of the current.