The Effect of Carbon Dioxide Tension Upon the Ability of Goldfish to Abosorb Oxygen at Low Tension

Within recent years much has been contributed to our knowledge of the physiology of respiration. Van Slyke (1921) in a study of the carbon dioxide carriers of the blood concluded that hemoglobin is almost as completely responsible for the transport of CO₂ in the blood as it is for the transport of oxygen. And that from 80% to 95%, sometimes possibly all, of the alkali furnished to neutralize the CO₂ that enters the venous blood comes from the hemoglobin.

Powers (1922) found that species of marine fishes have an optimum pH of more or less wide range for absorbing oxygen from sea water at low tension. He suggests that the CO₂ tension of the sea water is the limiting factor; and that the optimum CO₂ tension for a species depends upon the alkaline reserve and the optimum pH of the blood, also that the individual variations of a given species might depend upon the individual variations in the alkaline reserve of the blood. These suggestions are in accord with experiments of Henderson (1920) on the relation of the alkali reserve and oxygen tension of the blood in aoclimitixation to high altitudes.

It has been long known that. with very few exceptions, red salmon go to spawn up streams which are headed by lakes, but the phenomenon is yet unexplained. It fact most fishes in their migratory movements seek streams which drain lakes. Recently, it was found ( by Powers and Hickman 1928) that lakes and rivers draining lakes have a decidedly lower carbon dioxide tension than rivers not red by lakes. So, since the red salmon select the stream having a lower carbon dioxide tension, any correlation which might be established between the carbon dioxide tension and the ability to absorb oxygen would be of interest.

In this dissertation are recorded the results of a series of experiments performed to determine whether the carbon dioxide tension of water affected the ability of goldfish to absorb oxygen. Somewhat similar experiments were performed by Powers (1922) to determine the ability of marine fishes to extract oxygen from sea water at different hydrogen ion concentrations. It was found that the ability to absorb oxygen at low tension was more or less dependent upon the hydrogen ion concentration.

Subsequently the work of Powers, Shelford, and others indicate that organisms are affected more directly by carbon dioxide tension than by the pH as such.