ADDITIONAL MECHANISMS FOR THE ORIGIN OF BUBBLES IN ANIMALS DECOMPRESSED TO SIMULATED ALTITUDES* Bx W. E. BERG, MORGAN HARRIS, D. M. WHITAKER, AND V. C. TWITTY

In a series of studies, described separately (Whitaker et al. (1945), Harris et al. (1945)), it has beenshown that muscular activitycauses bubbles to form in decompressed animals, and that high blood concentrations of dissolved gases (e.g. CO2 or air) facilitate this effect, decreasing the degree of muscular activity required. Aside from the facilitating effect of the CO, produced, the muscular activity is believed to exert its effect largely through the physical consequences of mechanical disturbance. Blinks (unpublished), Dean (1944), and E. Newton Harvey (unpublished) have shown in models that mechanical agi .ration, by creating "negative pressures," causes bubbles to form in fluids (including blood) that are supersaturated with gases. However, the presence of "nuclei" (e.g. minute bubbles or gas films) which serve as centers for bubble growth is apparently necessary. Assuming that nuclei are involved in bubble formation in animals, it is important to investigate means by which they may form within the body, or be introduced from without. In the experiments to be described, a possible source of entry of nuclei has been explored and also new methods of producing nuclei and bubbles within the body in the absence of muscular activity have been found.