Field Studies of a Peromyscus Population in an Area Treated with DDT

the minimal lethal dose for this species is near the 2,500 mg./kg. level. Chronic toxicity occurred in meadow mice at 0.2 per cent DDT in the diet, as shown by the development of marked tremors and the death of two among five animals within the period of 28 days. The five fed at the 0.4 per cent level died by the 21st day of the feeding period. All animals fed at levels lower than 0.2 per cent of the diet survived the 31-day test period. Three of six white-footed mice dosed