Summary and conclusion
The float gases of Physalia contain carbon monoxide. The amount varied from 0.21% to 6.07% of the total. It is suggested that variations in carbon monoxide content may reflect differing functional states in the organism. The composition of the gas in the pneumocyst may change qualitatively and quantitatively in 24 hours. When the float was inflated with pure carbon monoxide this gas was diluted approximately 4-fold during the following 66 hours. During this same period the concentration of oxygen and carbon dioxide increased about the same extent. Concentration of nitrogen in the float gas increased 3-fold during this same period. These changes in composition of float gases could result either from active secretion from the gas gland or from passive diffusion through the wall of the pneumocyst. Structural considerations make this latter possibility considerably more remote than active secretion by the gas gland.
