192 



COLORATION IN LEFriNOTARSA. 



Experiment 20. — To determine the effect of a considerable decrease in relative humid- 

 ity upon the color and color pattern of L. decemlineata. 



Conditions. — Relative humidity on the average 14 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, 

 3,860 eggs were used which were taken at random and subjected soon after 

 being laid to the conditions of the experiment. From these 2,000 larvae were 

 hatched. 



The conditions of the experim.ent were as follows : 







Table 82. — Humidity conditions. 









Humidity— 



7 a. m. 



10 a.m. 



I p. m. 



3p.m- 



8p, m. 



Maxi- 

 mum. 



Mini- 

 mum. 



Aver- 

 age. 



Deviation 



from 

 normal. 



In nature 



In experiment. 



Per ct. 



100 



95 



Per ct. 

 65 



55 



Per ct. 



50 



40 



Per ct. 



55 

 40 



Per ct. 



100 



70 



Per ct. 

 100 

 100 



Per ct. 



43 

 30 



Per ct. 



74 

 60 



Per ct. 





 -14 



In this series of experiments 38 per cent died in the larval stage, 42 per cent 

 in the pupal, and 20 per cent emerged. The larvae were all small in size and 

 light in color, and the basal pleural spots were wanting. The imagines were 

 25 per cent below the average size of the parent, and were strongly albinic. 

 The hypodermal color was light yellow. On the epicranium the spots were 

 entirely absent in 70 per cent of the variates, and in the remainder rudiments 

 of g and g' only were found. On the pronotum the spots f and /' and d and d' 

 were absent and b and b' and e and e' were reduced to mere traces. On the 

 elytra all the stripes were reduced posteriorly and the anal and costal were 

 absent. The ventral surface was almost unicolorous, traces of the outer ster- 

 nal spots only being found in the thoracic and anterior abdominal region. The 

 entire lot was strongly albinic, as may be seen in the following seriations : 



Table 83. — General color of beetles used. 



Class 



3 



4 



5 



6 



7 



8 



9 



10 



II 



12 



13 





P.ci. 



P.ct. 



P.ct. 



P.ct. 



P.ci. 



P.ct. 



P.ci. 



P.ci. 



P.ci. 



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. 



2 



12 



40 



23 



10 



7 



3 



2 



I 







Empirical mode of parents. 9 



Empirical mode of control 9 



Empirical mode in experiment 5 



Modal deviation of parents o 



Modal deviation of control o 



Modal deviation in experiment. . . — 4 



