THE ANAEROBIC GASEOUS METABOLISM OF THE ROACH, CRYPTOCERCUS PUNCTULATUS SCUDDER

¹ From the Biological Laboratories, Harvard University, Cambridge, Mass.

Fully-grown specimens of Cryptocercus punctulatus Scudder had an average oxygen consumption of 46.1 cu. mm. per gram per hour at 7.5° C. and 28.5 cu. mm. per gram per hour at 5° C. The average respiratory quotient was 1.09.

The production of combustible gases by the intestinal protozoa was found to be much less than that previously reported for the termite, Zootermopsis.

Complete exclusion of oxygen was fatal to the insects if continued for more than 5 or 6 hours.

The extra oxygen consumed during oxidative recovery from a period of anaerobiosis lasting 1 hour was, on the average, three times as great as the amount of oxygen missed. Recovery was complete at the end of 4 hours after the re-admission of air.

The carbon dioxide excreted during anaerobiosis was 80 cu. mm. per gram in 1 hour at 5° C. and was equal to the amount of carbon dioxide retained during recovery, indicating that the carbon dioxide evolved during anaerobiosis was probably all derived from the acidification of bicarbonate.

In defaunated roaches the average oxygen consumption at 5° C. was 44.6 cu. mm. per gram per hour. The respiratory quotient was 0.69.

In insects investigated 1 day after defaunation the extra oxygen consumed during recovery from anaerobiosis amounted to only 130 per cent of the oxygen debt. At 6 days after defaunation 200 per cent of the debt was paid off, and at 8 days, 260 per cent.

Insects which had undergone the defaunation treatment, but in which defaunation was not complete, owing to the presence of resistant stages of the protozoa, had a heightened rate of oxygen consumption but behaved like normal insects, paying off 300 per cent of the debt.

The anaerobic carbon dioxide excretion and carbon dioxide retention during recovery of defaunated roaches were the same as those of untreated individuals.