MODIFICATION OF COI.OR. 



193 



Experiment 21. — To determine the effect of a large average decrease in the relative 

 humidity upon the coloration of L. decemlineata. 



Conditions. — Relative humidity on the average 24 per cent below that in 

 nature, with other conditions normal. 



Apparatus. — The same as in experiment 16. 



In this series of experiments, conducted during the years 1899 to 1904, 

 there were used 3,000 larvae, hatched from 5,300 eggs collected at random and 

 subjected to the conditions of experiment soon after being laid. The condi- 

 tions were as follows : 



Table 84. — Humidity conditions. 



Humidity— 



7 a. m. 



10 a.m. 



I p.m. 



3 p.m. 



8 p.m. 



Maxi- 

 mum. 



Mini- 

 mum. 



Aver- 

 age. 



Deviation 



from 

 normal. 



In nature. . . . 

 In experiment . 



Per ct. 

 100 



75 



Per ct. 

 65 

 40 



Per ct. 

 50 

 30 



Per ct. 

 55 

 40 



Per ct. 

 100 



65 



Per ct. 

 100 



83 



Per ct. 

 43 

 25 



Per ct. 

 74 

 50 



Perct. 





 -24 



In this series of experiments 52 per cent died in the larval stage, 40 per 

 cent in the pupal, and 8 per cent emerged. All larvae and imagines were 

 developed in the same directions as those in experiment 20, although to a 

 greater extent. The size of the imagines was 38 per cent below that of the 

 parents and the general color appearance was strongly albinic, as is shown in 

 the following table : 





Table 8s.— General cc 



lor of beetles used. 









Class 



I 



2 

 P.ct. 



3 

 P.ct. 



4 

 P.ct. 



5 

 P.ct. 



6 

 P.ct. 



7 



P.ct. 



8 

 P.ct. 



9 

 P.ct. 



10 

 P.ct. 



II 

 P.ct. 



12 

 P.ct. 



13 

 P.ct. 





P.ct. 



Parents 



. . 









I 



2 



5 



20 



42 



18 



9 



2 



I 



Control 











2 



7 



8 



17 



37 



19 



8 



I 



I 



Experiment. . 



3 



6 



43 



30 



12 



5 



I 







.. 







•• 



Empirical mode of parents 9 



Empirical mode of control 9 



Empirical mode in experiment .3 



Modal deviation of parents o 



Modal deviation of control . o 



Modal deviation in experiment . — 6 



Experiment 22. — To determine the effect of an extremely low relative humidity upon 

 the color and color pattern of L. decemlineata. 



Conditions. — Relative humidity on the average 40 per cent below that in 

 nature, with other conditions normal. 



Apparatus. — The same as in experiment 16. 



In these experiments, conducted during the years 1899 to 1903, 6,500 larvae, 

 hatched from 14,300 eggs taken at random, were used. The conditions of 

 experimentation were as follows : 



