1. The repeated elevation of body temperatures of male and female rabbits to 41° and 42°C. from 2 to 5 times per week by short radio waves (30 m.), beginning from 29 to 171 days of age and extending through their first period of gestation, failed to injure their growth or to interfere with mating, fertilization, or the development of young in utero. Litter mates were kept for controls.
2. The rabbits exposed to the short wave fevers showed, in the majority of cases, a greater percentage gain in weight than did the control litter mates.
3. The kindling age of the treated group was, on an average, 2 weeks older than the non-treated group.
4. The fever-treated females averaged five and one-half young per litter with an average weight of 41 gm., while the untreated females averaged seven per litter with an average weight of 36.5 gm.
5. The repeated elevation of body temperature by short radio waves is a safe procedure when temperatures greater than those within physiological limits are not employed.