28 ROBERT \V. HKGNER. 



The data from experiments C.B. 42 and C.B. 70 indicate that 

 darkness has no retarding nor accelerating influence upon the 

 embryonic development, upon the rate of larval growth, or upon 

 the period of pupation. 



One other conclusion that may be arrived at from these experi- 

 ments is that darkness has no effect upon the coloration of the 

 eggs, larvae, pupae or adults of the species studied. Frequent 

 examinations were made during the growth of the beetles reared 

 in the dark, but no variations from the normal were discovered 

 that could be attributed to the absence of light. This confirms 

 Przibram's (1906) results for the praying mantis, the entire post- 

 embryonic development of which was carried out in the dark 

 without producing any effect upon the coloring. 



2. The Influence of Colored Lights. 



Method and Data. Experiment C.B. 64. This experiment is 

 the only one attempted with a view to testing the effects of 

 colored lights upon the embryonic development of beetles' eggs; 

 but it indicates that color has no very striking influence upon the 

 rate of development. 



Several eggs from a single batch of 15, which were laid at 10:30 

 A.M. on June 24, were placed in each of six cylindrical tubes. 

 These tubes were then closed with rubber corks through each of 

 which were inserted a thermometer and a tube for ventilation. 

 These cylindrical tubes were then immersed in different colored 

 liquids prepared according to Yung (1878). The colors used 

 were red, blue, yellow, green and violet, and a tube was kept in 

 pure water as a control. The temperature in the different tubes 

 was practically identical. The eggs in the white, yellow, green 

 and red lights hatched on June 29; those in the violet and blue 

 were ready to hatch on the same day, but were prevented by 

 fungus growths. 



Discussion and Conclusions. Many experiments have been 

 performed with eggs of a number of species of anim.ils to deter- 

 mine the influence of colored lights upon their dc\ dopment. 

 Yung (1878) used freshly laid eggs of the frog, Rana esculeiita and 

 R. temper aria. At the end of two months all of the tadpoles in 

 the green light were dead, thoM- in tin- white and yellow liglits 



