EEACTIONS OF DAPHNIA PULEX TO LIGHT AND HEAT. 363 



ff « o " 



wM fflMmmm k. 



I 



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; /, //, ///, 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; M , mirror. Scale $. 



