[Relationship between the heat resistance of different muscles and frog viability during heat selection]

An attempt was made to elucidate the relation between the survival of mature frogs Rana temporaria during sudden (unforeseen) thermal selection and the heat resistance of several muscles: m. interfalangealis, m. ileofibularis, m. sartorius, m. gastrocnemius and m. rectus abdominis. It has been found that of greater selective value are the individuals with lower heat resistance not in all muscles, but in those having lesser heat resistance, such as m. ileofibularis and m. sartorius.