ABSTRACT
Eighty years ago Lankester(1867) identified spectroscopically the red blood pigment of the larvae of Chironomus plumosus as haemoglobin. Subsequently (1873) he correlated its presence with the fact that they inhabit stagnant ponds and putrescent mud where the amount of accessible oxygen must often be small. Since then it has been generally assumed that their haemoglobin enables the larvae to live in surroundings deficient in oxygen, and experimental evidence for this has lately been supplied by Harnisch (1936) and by Ewer (1942). These workers compared the metabolism of normal larvae with that of larvae whose haemoglobin had been made functionless by conversion to carboxyhaemoglobin. They found that the pigment was only used as an oxygen carrier at low pressures of oxygen; it is used to the greatest extent in water which is 22 % saturated with air at 17° C. Ewer also made a series of measurements of the oxygen content of the pond from which her larvae were obtained and found oxygen concentrations corresponding to 32 % air saturation or less for periods of at least 16 consecutive hours. Thus it may be assumed that in nature the haemo-globin of the species with which Ewer worked is of functional value.
And possibly above it. My data, not extending above air saturation, do not settle this point.
Hyman (1932) records that Nereis in tubes has a lower metabolism, more independent of declining oxygen concentrations, than free animals.
