of 1 lb per acre of a relatively easily manufactured chemical, without undue aircraft effort. By the end of the war development was in fact sufficiently advanced to make this form of attack practicable, using the agents and weapons already available. The American authorities had actually built up a stock of material and were planning an attack on the main islands of Japan early in 1946, calculated to destroy some 30% of the total rice crop. Chemical Agents 4. In addition to the substances already examined in this country, approximately 800 chemical substances have been examined in America to determine their relative power to injure or destroy plants.