146 JOSEPH KRAFKA, JR. 



BIBLIOGRAPHY. 

 Kopec, S. 



'22 Journ. Exp. Zool., 36, 451;. 



Krafka, J., Jr. 



'ig-'zo Gen. Physiol., II., 409, 433, 445. 

 '20 Gen. Physiol., III., 207. 



May, H. G. 



'17 BIOL. BULL., XXXIII., 361. 

 Seyster, E. W. 



'19 BIOL. BULL., XXXVII., 168. 

 Tice, S. C. 



'14 BIOL. BULL., XXVI., 221. 

 Weismann, A. 



'64 Zeitsch. f. Wiss. Zool., XIV., 101. 

 Zeleny, C. 



'17 Proc. Indiana Acad. Sc., 73. 

 Zeleny, C., and Mattoon, E. W. 



'15 Journ. Exp. Zool., XIX., 514. 



EXPLANATION OF FIGURES. 

 PLATE I. 



FIG. i. Frontal section through the anterior end of a two-day larva. The 

 imaginal disks (7) of the compound eye are shown attached to the so-called 

 pharynx and are far removed from the supra-esophageal ganglia (G). 300 X. 



FIG. 2. Sagittal section through the anterior end of a three-day larva. 

 The imaginal disk (7) is shown in union with the brain. 300 X. 



FIG. 3. Section through the imaginal disk of a four-day larva. The cells 

 are arranged around a central axis, while the groups correspond to the omma- 

 tidial arrangement in the adult. 1300 X. 



FIG. 4. Section through the imaginal disk of another four-day larva. The 

 rudiments of the ommatidia appear as rosettes of four or six cells in cross- 

 section. 2100 X. 



FIG. 5. Cross-section of the head of a two-day pupa (sixth day), showing 

 the compound eye in place and the ommatidia present as such. The latter are 

 connected to the optic tract by nerve fibres. 300 X. 



FIG. 6. The same ommatidia greatly magnified. The rhabdome, six retinu- 

 lae cells, the supporting cells, and the bristles are all clearly shown. The fig- 

 ures at the side represent cross-sections at two different levels. 1300 X. 



FIG. 7. Longitudinal sections through the ommatidia of a pupa slightly 

 older than that of Fig. 6. 1300 X. 



