Summary
The Root effect was measured in hemolysates from representatives of 56 genera of Amazonian fishes. Hemolysates from several species of air-breathing fishes were found to have Root effects, contrary to published hypotheses. Hemolysates from Potamotrygon, a fresh water ray, exhibit a Root effect under our experimental conditions. The pattern of Root effect distribution correlates positively with the distribution of choroid retia mirabile and swimbladders, but not with the distribution of swimbladder retia mirabile; it is proposed that the former is the more primitive structure which is associated with the origin of Root effect hemoglobins. Some cf the fish hemoglobins differ spectrally from one another. The positions of the absorption maxima of the deoxyhemoglobins range from 553 nm (Lepidosiren paradoxa and Potamotrygon sp.) to 560 nm (Plagioscion). Occurrence of Root effects is not correlated with the complexity of the hemoglobin electrophoretic pattern, although several species are found to have multiple hemoglobin systems in which the Root effect is restricted to certain components.