Metabolic Rate of Early vestigial and wild-type Prepupse of Drosophila melanogaster in Relation to Genotype, Sex, and Size

SUMMARY.

• 1
   Using a manometric method, the oxygen consumption of early D. melano-gaster prepupae was studied.
• 2
   It was found that males respired faster per unit wet weight than females, that wild-type respired faster than vestigial, and that the heterozygote did not differ from the wild-type.
• 3
   It was then noticed that the prepupae in the different groups differed in size, owing to differences in population density in the culture bottles. On modifying the culture conditions so that the prepupae were of the same size, the differences in respiration between the sexes and between vestigial and wild-type disappeared.
• 4
   It is concluded that, in early prepupae, (a) significant differences in respiratory rate between the sexes, and between the genotypes employed, are absent; (6) that body-size has considerable influence on the respiratory rate, large animals consuming less oxygen, per mg. wet weight, than animals of smaller size. The importance of controlling the size factor in work of this type is emphasized.