Studies on the Bar Series of Drosophila V. the Effects of Reduced Atmospheric Pressure and Oxygen on Facet Number in Bar-Eyed Drosophila.

HE investigations which have been directed toward a clarification T of the kinetics of facet determination in the Bar series of alleles in Drosophila have, heretofore, been concerned largely with the use of temperature as a suitable and easiIy controlled variable. The manner in which temperature data have been used is clearly set forth in the work of a number of investigators, notably, KRAFKA, 1920; ZELENY, 1923; DRIVER, 1926; 1931; LUCE, 1931; HERSH, 1934; and MARGOLIS, 1935 a and b. The present paper is the outgrowth of an effort on the part of the author to find other environmental agencies which might be brought to bear upon the problem. The data presented here deal with the effects of reduced atmospheric pressure, and of a pure oxygen atmosphere on the number of facets in the compound eye.