— 48 — 



of the section is denoted in the figure of the transverse section (fig. 5) 

 by 3—3. Stained with Delafield's haeraatoxylin, Eosin. i^^/i. 



Fig. 4. Section through the same object parallel to the preceding 

 section, but nearer to tlie anterior and dorsal surface of the eye. The 

 direction of the section is denoted in fig. 5 by figures 4—4. Stained as 

 above. i^Vi. 



Eig. 5. Transverse section through the right eye of D. ichneumonea on 

 the level of the chiasma which is seen in the middle of the drawing in 

 the shape of an elongated white oval, a — anterior aspect, p — posterior, 

 d — dorsal, v — ventral. The direction of the section is denoted in fig. 3 by 

 figures 5 — 5. Depigmentated. Stained as above -|- picric acid ^^Vi. 



Fig. 6. Four facets of the ventral part of the transverse section of 



fig. 5. 320/1. 



Fig. 7. Five facets of the dorsal part of the same section 320/i. 



Fig. 8. Three facets of the transverse section, dorsal aspect, near the 

 eye— stalk of the same object as in fig. 6 and 7. ^'^Ix. 



Fig. 9. Three ommatidia from the middle part of the sagittal section 

 in fig. 3, 7^/i. 



Fig. 10. Transverse section of the facets from the dorsal part of the 

 left eye of D. pulchella. On the right side the section has passed 

 only through the upper layer of facets, ''^/i. 



Fig. 11. Transverse section through six ommatidia of D. pulchella. On 

 the right the section has passed through the cells of the crystalline cone 

 The same object as in fig. 3, i39o/i_ 



Fig. 12. Transverse section through two ommatidia of the dorsal eye 

 region on the level of the retinular nuclei 1 — 6. Same object, ^^^ii. 



Fig. 13. Transverse section through five dorsal ommatidia proximally 

 to the retinular nuclei 1 — 6 and distally to nuclei 7. The upper ommatidia 

 in the drawing are on one side, and the lower ommatidia — on the other 

 side of the plane of symmetry dividing the eye in two equal parts with 

 respect to the arrangement of the rhabdom cells. The same preparation 

 as in fig. 3. i39o/i. 



Fig. 14. Transverse section through five dorsal ommatidia on the 

 level of the retinular nuclei 7. The same object. i»io/i. 



Fig. 15. Transverse section through the row of „rods" of the molecu- 

 lar layer of the exterior optical ganglion. Same object as in fig. 4. i^^/i. 



Fig. 16. Slightly reconstructed transverse section through the ventral 

 ommatidium of the same object, as in fig. 3, and on the same level as in 



fig. 13. 1390/1. 



