MODIFICATION OF COLOR. 



I8 7 



^Deviations in temperature, - from the normal, - used in experiments. ^ 



Text-figure 13. To illustrate the results obtained in a series of experiments of which two (14 and 15 

 are described in the text, the results obtained in the others being shown by the figure. 



x Deviations in temperature, - from normal,- used in experiment , 



5 10 15 5 



5 10 15 5 10 15 5 10 15 



Text-figure 14. To illustrate the results that were obtained in a series of experiments as described 

 in the text when continued for a number of generations. Kach of the different lines represents a 

 series of experiments and the arrow heads the direction takeu by different parts of each set when 

 the stimulus was removed or applied. In all the sets of experiments represented lines going toward 

 the modal line of the parents indicate the rapid return of the beetles to the modal couditiou when 

 the stimulus was removed. 



