Shivering is influenced in the guinea-pig by temperature alterations in the cervical part of the vertebral canal, but it is independent of the temperature in the hypothalamus. For the quantitative determination of the relationship between body surface temperature, cervical temperature, and shivering, the two temperatures were varied independently in guinea-pigs of the age of 4 and 8 weeks while the eleetrieM activity of two muscle groups was continuously recorded as a measure of shivering. An electrical activity of 5 mV/see was taken as threshold activity. Threshold activity could be elicited by decreasing either the cervical or the surface temperature; the decrease of cervical temperature necessary for producing the threshold activity was inversely related to the temperature level of the body surface, and vice versa. By plotting the various combinations of the two temperatures which had produced threshold activity into a co-ordinate system (with the two temperatures as ordinates) a shivering threshold curve is obtained which has the appearance of a rectangular hyperbola. In accordance with the hyperbolic function the shivering threshold activity is a function of the product of the two temperature deviations, A v~ and A 0 0 (difference between the temperature given by the respective asymptote and the actual temperature value). Thus the mean body temperature, rather than any local temperature within the body core, may be thought of as the controlled variable.