[Variability of heat resistance of frog muscle tissue in Ringer's solution]

The variability in the initial level of heat resistance of muscles was found to decrease with increase in the duration of keeping the frogs in vivarium. However, the variability in the resistance of isolated muscles kept in Ringer's solution during 90 min. is independent of this factor and lesser than the initial one. The data obtained suggest that the narrowing of the variability in the resistance of muscles kept in Ringer's solution is determined by the dispersion of the initial level of the resistance. This phenomenon is only observed when the individual variability in the resistance of muscles is sufficiently high immediately after their isolation.