AUTHOR'S ABSTRACT OF THIS PAPER ISSUED BY 
THE BIBLIOGRAPHIC SERVICE, DECEMBER 22 
Le REACTIONS TO LIGHT AND ,TO GRAVITY. IN 
DROSOPHILA AND ITS MUTANTS 
ROBERT STANLEY McEWEN 
Columbia University, New York City 
THREE FIGURES 
INTRODUCTION 
The presence in the Columbia laboratory of a great variety of 
mutant stocks of Drosophila ampelophila involving differences 
in the size of wings and color of eyes has offered an exceptional 
opportunity to investigate the relation of these variations to the 
responses of the fly to light and to gravity. The wing mutations, 
moreover, have been useful in checking up results obtained by 
removal of part of the normal wings, while the differences in eye 
color have made possible a novel series of experiments on the 
effects of lights of varying wave lengths. 
Finally, in one case it has been possible to study the direct 
hereditary modification of a reaction system apart from any sig- 
nificant morphological variation. 
Although a considerable amount of work on the behavior of 
Drosophila toward light and gravity has already been done, 
notably by F. W. Carpenter, W. H. Cole, Fernandus Payne, A. 
O. Gross and F. E. Lutz, it was nevertheless found necessary to 
try out a number of preliminary experiments in order to deter- 
mine the source of certain discrepancies in the results of these 
investigators. This was particularly true in regard to the effect 
of the factors of age and sex on normal flies. 
I wish at this point to express my sincere thanks to Dr. T. H. 
Morgan for his many helpful suggestions in the course of my ex- 
periments. I also wish to express my indebtedness to Dr. Fran- 
cis H. Herrick for allowing me the use of the laboratory at 
Western Reserve University during the summers of 1915 and 
49 
THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 25, NO. 1 
