On the Temperature Characteristics for Frequency of Breathing Movements in Inbred Strains of Mice and in Their Hybrid Offspring. I

Young mice of a selected line of the dilute brown strain of mice exhibit over the range 15-25 degrees C. (body temperature) a relation of frequency of breathing movements to temperature such that when fitted by the Arrhenius equation the data give a value for the constant micro of 24,000+/- calories or, less frequently, 28,000+/-. Young mice of an inbred albino strain show over the range 15-20 degrees C. a value of micro = 34,000+/-, or, less frequently, 14,000+/-, with a critical temperature at about 20 degrees C. and a value of micro = 14,000+/- above 20 degrees C. The F(1) hybrids of these two strains, and the backcross generations to either parent strain, exhibit only those four values of the temperature characteristic observed in the parent strains and none other. One may therefore speak of the inheritance of the value of the constant micro, but the inheritance shows in this instance no Mendelian behavior. Furthermore there appears to be inherited the occurrence (or absence) of a critical temperature at 20 degrees C. These experiments indicate the "biological reality" of the temperature characteristics.