The Eye« of Dactylopius. 89 



Fig. 2. An outline drawing of the dorsal surface of the head to show the 

 Position of the dorsal accessory eyes. Drawn with a dissecting microscope. 



Fig. 3. The thickening of the ventral hypodermis of the head from which 

 the ventral acce-ssory eyes develop. Third nymphal period. 



Fig. 4. Shows the beginning of the visual rods and of the nerve. Latter 

 part of the third nymphal period. 



Fig. 5. Demonstrates the position of the comeal hypodermis befor it is 

 superimposed upon the visual rods. Early part of the fourth nymphal period. 



Fig. 6. This shows the corneal hypodermis superimposed upon the visual 

 rods. Fourth nymphal period ; pigment not yet deposited. 



Fig. 7. This is an early stage in the formation of the iens. The figure also 

 shows the iris cells which appear about this time. Fourth nymphal period. Pig- 

 ment now first begins to be deposited. 



Fig. 7a. Shows the Iens at a slightly earlier period than in fig. 7. 



Fig. 8. This demonstrates an advanced stage in the formation of the Iens. 

 Latter part of the fourth nymphal period. 



Fig. 9. The pigmented eye of the adult. The tube of the microscope was 

 not drawn out for this drawing. 



Fig. 10. The depigmented eye of the adult. 



Fig. 11. This shows a cross section of the visual rods. 



Fig. 12. The primary eye depigmented. 



Fig. 13. A longisection of the head and the anterior portion of the thoras 

 to show the mouth opening and the developing ventral accessory eye. The latter 

 is made slightly diagrammatic. Third nymphal period. Drawn with number 6 

 ocular. 



Fig. 1-4. A group of phagocytic cells. 



Fig. 15. This shows the entrance of the nerve into the cerebral ganglion at 

 the time of the third nymphal period. The direction of the nerves to the dorsal 

 and ventral eyes respectively is indicated by the arrows. 



Fig. 16. A transverse section of the head to show the relation of the six 

 eyes to each other and to the cerebral ganglion. The figure is slightly diagram- 

 matic and was drawn with a low power ocular. 



