324 CHARLES ZELENY 



14. The fact that ultra-bar occurred in the course of a down- 

 ward selection of bar is interesting, though probably not signif- 

 icant, in view of other mutations affecting facet number which 

 have not always been in the direction of selection. 



Acknowledgments 



In common with other students of Drosophila, I have had the 

 generous help with materials and suggestions of Prof. T. H. 

 Morgan and Drs. A. H. Sturtevant and C. B. Bridges. It is a 

 pleasure also to express my indebtedness to Dr. Joseph Krafka, 

 Jr., to whose untiring care of the stocks and tests the success 

 of these experiments is largely due. I am also under obligation 

 to Prof. A. R. Crathorne, who was kind enough to go over the 

 method of factorial units which I have used in tabulating the 

 data. 



BIBLIOGRAPHY 



Khafka, Joseph, Jr. 1920 The eflfect of temperature upon facet number in the 

 bareyed mutant of Drosophila melanogaster. J. Gen. Physiol., v. 2. 



May, H. G. 1917 Selection for higher and lower facet numbers in the bar-eyed 

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 Bull., vol. 33, pp. 361-395. 



Seyster, E. W. 1919 Eye-facet number as influenced by temperature in the 

 bar-eyed mutant of Drosophila melanogaster (ampelophila). Biol. 

 Bull., vol. 37, pp. 168-182. 



TiCE, S. A. 1914 A new sex-linked character in Drosophila. Biol. Bull., vol. 

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Zeleny, C. 1917 Full-eye and emarginate eye from bar-eye in Drosophila 

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1917 Selection for high-facet and low-facet number in the bar-eyed 

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1918 Germinal changes in the bar-eyed race of Drosophila during 

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1919 A change in the bar gene of Drosophila involving further decrease 

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Zeleny, C., and Mattoon, E. W. 1915 The effect of selection upon the 'bar 

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