Abstract
An investigation to determine the relative roles of various factors in the variability of expression of a chromosomal inversion in Drosophila melanogaster. Starvation, due to crowded cultures or to the eggs being depleted of some essential substance, has a marked effect on the expression. The extremes of the temp, range have less effect than the intermediate temps. Extra Y-chromosomes decrease the effect. Genetic modifiers may increase the effect. Sex, age, and age of parent have no influence. The results are correlated with the role of heterochromatin on the chromosome.