A. R. MOORE AND W. H. COLE 335 



to the logarithm of the intensity of the stimulus. Putting R, the 



rate of response, for S, transposing and putting k for - , the integrated 



c 



equation of Fechner becomes logel = kR — K. 



Substituting the experimental values of loge/ and of R in this equa- . 

 tion and solving by the method of least squares for k and K we obtain 

 k = 1.09 and K = 2.71. These quantities when put into the equa- 

 tion for each value of loge/ in turn yield a series of calculated values 

 for R, as shown in the last column of Table II. 



When the rates are plotted as abscissae against the values of loge/ 

 as ordinates the result is a straight line (Fig. 1), showing at a glance 

 that the rate of response of the organism to light is proportional to 

 the logarithm of the intensity of the illumination. This demon- 

 strates that the Japanese beetle responds to light in accordance with 

 the Weber-Fechner law. 



SUMMARY. 



Light and a temperature above 23°C. are necessary for the activity 

 of Popillia. 



The effect of light as indicated by the rate of locomotor response is 

 related to light intensity according to Fechner's expression of Weber's 

 law. 



