1 86 



COLORATION IN LEPTINOTARSA. 



The temperature records are as follows : 



Table 72. Temperature conditions. 



In this experiment the larvae showed the same color changes as those in 

 No. 10. The mortality was 60 per cent in the larval stage, 12 per cent in the 

 pupal, and 38 per cent emerged as imagines. The seriations of these are 

 shown in the following table: 



Table 73. General color of beetles used. 



Empirical mode of parents 9 



Empirical mode of control 9 



Empirical mode in experiment. .. . 9 



Modal deviation of parents o 



Modal deviation of control o 



Modal deviation in experiment. . . o 



In these experiments the adult coloration was not affected by temperature 

 stimuli applied throughout the larval stage alone. This fact is made clearer in 

 text-figure 13, where the curve of the entire series of these experiments is rep- 

 resented. Not the slightest indication is here apparent of any influence upon 

 imaginal coloration of the conditions of temperature to which the larvae have 

 been subjected. 



The modifications of coloration produced by external stimuli during the 

 ontogeny of L. decemlineata are purely somatic variations, there being no 

 accumulations of the effects of stimuli applied at one stage upon the coloration 

 of a later one. The influence of temperature upon coloration is felt during 

 the development of coloration of a particular instar only, and consists in the 

 acceleration or retardation of the action of the color-producing enzymes. 

 Neither is there any accumulation of the results of repeated temperature stim- 

 uli nor any increase of response even when repeated for several generations. 

 This is apparent in text-figure 14, where are given the results derived from a 

 series of experiments made in the years 1901 to 1904, in which these beetles 

 were subjected to the conditions of increased or decreased temperature during 



