On the Function of Haemoglobin in Chironomus

Abstract

At 17° C. the oxygen consumption of Chironomus larvae shows little diminution when the oxygen concentration in the water decreases from 7·5 c.c. per litre (air saturation) to about 3 c.c. per litre. Below 3 c.c. per litre a further decrease in oxygen concentration causes a falling ôff in oxygen consumption. At 17° C. the oxygen consumption of Chironomus larvae whose haemoglobin has been converted to carboxyhaemoglobin is as great as that of normal animals from air saturation down to 3 c.c. per litre. Below this point the oxygen consumption is less than that of normal animals. It follows that at 17° C. the haemoglobin of Chironomus larvae from well aerated water does not function in oxygen transport at air saturation, but only at oxygen pressures below 3 c.c. per litre. Some observations of the habitat of the larvae show that they can live in situations where oxygen concentrations of less than 2 c.c. per litre persist for periods of at least 16 consecutive hours. The larvae are also to be found in situations where the oxygen concentration is high.