Environmental Factors Other than Temperature Affecting Facet Number in the Bar-eyed Mutant of Drosophila

In a recent paper the author 1 has undertaken to show the relation between temperature and 'the facet number in the bar-eyed mutant of Drosophila mdanogaster Meig. Since it was essential to know the part played by other environmental factors the experimental evaluation of some of these was carried out. While these experiments were not as critical as was desired, they give some idea as to the respective value of food, humidity, and evaporation as these are commonly represented in Drosophila culture technique. The following data are submitted, then, not as a final analysis, but rather as a basis for further work. The work in all cases was carried out on the Ultra-bar mutant. For a direct comparison the data on the effect of temperature are given in Table I. The temperature data are for the interval 23-29°C., as the experiments involving the other factors were carried out at these temperatures. An interesting suggestion for further work appeared in the analysis of the few experiments dealing with different kinds of foods. Since consistent results were obtained in three successive experiments it may be that they have some significance. I t is the experience of nearly all investigators rearing Drosophila, that fermented banana rapidly becomes acid at the high temperatures and that oviposifion is much retarded. In an attempt to eliminate