Day.— Eye of Crayfish. 
PLATE 5. 
Fig. 9a. Observation record of eye 141, dark 6 hr. Color, yellowish orange. 
Pronounced darkening in the upper half. 
Fig. 9b. Section of eye 141, X 41. The extent of the migration is about 
twice the width of the tapetal layer, but not out to the nuclei. 
Fig. 10. Photographic test of light-box for leakage of white light. A Seed’s. 
“Gilt Edge 27” plate, substituted for the animal as in text-fig. F, 
had six separate exposures made on it as follows: At 50 cm.: a, 
30 sec.; b, 60 sec.; c, 90sec. At150cm.: d, 270sec.; e, 540 sec. ;. 
f. 810 sec. 
