DEVELOPMENT OF THE COMPOUND EYE OF DRO- 



SOPHILA MELANOGASTER AND ITS 



BAR-EYED MUTANT. 1 



JOSEPH KRAFKA, JR., 

 UNIVERSITY OF GEORGIA, ATHEXS. 



A histological examination of the compound eye of Drosophila 

 tnelanog aster Meig., and its bar-eyed mutant, was made to deter- 

 mine its chronological development. The origin of this mutant is 

 known (Tice, 1914). Its germinal behavior has been shown to be 

 sex linked (Tice, 1914). Its major and minor fluctuations in the 

 homozygous condition have been given an exact expression by 

 Zeleny and Mattoon (1915), May (1917), and Zeleny (1917), 

 while the roles of the various environmental factors have been 

 evaluated by Seyster (1909) and Krafka (1919-20). 



The number of facets that are to form the compound eye of the 

 bar-eyed mutant is determined by the temperature at which the 

 larva passes a specific stage in development. This period is defi- 

 nitely established as the third day of larval life when the tempera- 

 ture is 27 C. (Krafka, 1920). 



The present paper establishes the condition of the imaginal disks 

 at that time and describes the subsequent changes that take place 

 in the growth and differentiation of the ommatidia through the 

 late larval and the pupal periods. 



Entire larvae, pupae, and adults were fixed in Benin's picro- 

 formol solution, representing developmental material of 24-hour 

 intervals over the entire life history. Records were kept of the 

 matings, fixation of material, and temperature. The latter ranged 

 from 25 C. to 28 C. Hot water and hot Gilsson's fluid were 

 used with some success. For cell detail, the brain, cord, and imag- 

 inal disks were dissected out and fixed in Flemming's strong solu- 

 tion. 2 



1 Contribution from the Zoological Laboratory of the University of Georgia, 

 No. 5. 



2 Acknowledgments are due Mr. Shelley C. Davis for drawing Fig. 8. 



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