Bulletin of the Museum of Comparative Zoology 
AT HARVARD COLLEGE. 
Vou. LITI. No. 6. 
THE EFFECT OF COLORED LIGHT ON PIGMENT-MIGRATION 
IN THE EYE OF THE CRAYFISH. 
By Epwarp C. Day. 
Wits Five Puates. 
CAMBRIDGE, MASS., U. S. A.: 
PRINTED FOR THE MUSEUM. 
DrEcEMBER, 1911. 
