REACTIONS OF DAPHNIA PULEX TO LIGHT AND HEAT. 



Q.B. 



363 



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FIGURE A. Apparatus for Giving a Band of Light Regularly Graded in Intensity. 



C. B., two 16-candle-power electric lamps; G, rays of light; 7, //, ///, course of rays; A, a dish containing solu- 

 tion of alum 10 cm. deep; H, frame for lens, L; E, screens to cut off light from ends of glass box, T; D, cloth 

 curtains to exclude light; F, table for apparatus; K, slit in table for passage of rays; Jl/, mirror. Scale J. 



