190 



COLORATION IN LEPTINOTARSA. 

 Table 77- General color of beetles used. 



Empirical mode of parents 9 I Modal deviation of parents o 



Empirical mode of control 9 ] Modal deviation of control o 



Empirical mode in experiment 7 | Modal deviation in experiment . 2 



Experiment 18. To determine the effect of a saturated atmosphere upon the coloration 



of L. deccmlineata. 



Conditions. Relative humidity 26 per cent above that in nature, with other 

 conditions normal. 



Apparatus. The same as in experiment 16 . 



In this experiment, which was conducted during the years 1899 to 1904, 

 2,000 larvae, hatched from 4,450 eggs, were subjected to the following condi- 

 tions : 



Table 78. Humidity conditions. 



In the experiments of this series 52 per cent died in the larval stage, 38 per 

 cent in the pupal, and 10 per cent emerged. In the larvae the hypodermal 

 color was a light, translucent, yellowish red, and the dark areas were small 

 and brown in color. All dorsal markings were wanting, as were also the pos- 

 terior four or five basal pleural centers. In the imagines the hypodermal 

 color was pale yellowish-white and the dark spots were much reduced in size. 

 On the epicranium h and h' were wanting and g and g' were represented by 

 mere traces of color. On the pronotum / and /' were absent entirely ; d and 

 d', b and b' were absent in 40 per cent of the variates, and e and e' in 12 per 

 cent. The spots a and a' were in 8 per cent of the variates divided into 

 anterior and posterior parts. On the elytra all stripes were reduced and the 

 anal was absent. On the ventral surface all spots were represented by mere 

 traces, and the entire series of middle sternals was absent. The legs, with 

 the exception of the tarsse, were devoid of color and the general appearance 

 was decidedly albinic, as is shown in the following seriations : 



