. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 68 JOHN B. BUCK AND MARGARET L. KEISTER B. Rate of oxygen uptake of control flies The oxygen consumption of individuals at rest was about 5 mm3/mg. dry weight/hour (Fig. 4), a rate comparable to that in several other insects. How- ever, occasional controls showed periods of uptake as great as those of poisoned flies ( up to at least 10 times the usual control rate) coincident with periods of walking or running. Perturbations due to a single such individual out of twelve are seen in the Dry Control rate in Figure 4 (see a
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 68 JOHN B. BUCK AND MARGARET L. KEISTER B. Rate of oxygen uptake of control flies The oxygen consumption of individuals at rest was about 5 mm3/mg. dry weight/hour (Fig. 4), a rate comparable to that in several other insects. How- ever, occasional controls showed periods of uptake as great as those of poisoned flies ( up to at least 10 times the usual control rate) coincident with periods of walking or running. Perturbations due to a single such individual out of twelve are seen in the Dry Control rate in Figure 4 (see also Fig. 7), which is otherwise not significantly different from that of the Wet Controls. 10 FIGURE 4. Oxygen uptake in normal and DDT-poisoned flies under dry and humid condi- tions (mean of representative series of 6 experiments). Thirty flies in each poisoned group, 12 dry controls, 6 wet controls. Cap lines from points indicate standard errors. The numbers of flies represented are 78 through 8 hours, 65 at S1/^ hours, 51 at 91/£ hours, and 35 at 10 hours. C. Effect of DDT on oxygen uptake The mean uptake of poisoned flies in a humid atmosphere rose steeply in about 3^o hours to over five times the control value, leveled off for about 3 hours, then declined gradually (Fig. 4). Some individuals showed brief early peaks 15-20 times the control level. The "dry" poisoned flies followed the same course for about 2 hours, but thereafter had very significantly lower uptakes (P<) whether calculated from initial weights or estimated weights at the times of meas- urement. That this is a true metabolic difference is indicated by the dry weight data given below (Fig. 5 and Table I) and by evidence (see Appendix) that oxy- gen uptake was measured with equal accuracy under wet and dry conditions. Ac- cordingly, it can be concluded that a dry atmosphere partly inhibits oxygen uptake in poisoned flies. A similar inhibition has been reported in certain normal insects
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