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June 22, 1935


JAMA. 1935;104(25):2259-2260. doi:10.1001/jama.1935.02760250037013

One of the fundamental requirements of all living organisms is the ability of constant adaptation to physical changes in the environment. Alterations in environmental temperature and humidity are most commonly considered in this connection; the compensatory mechanisms for variations in these factors have been extensively investigated. There are other environmental factors, however, that may exert a profound influence. Of these, one of the most interesting but apparently least studied is the effect of pressure.

Adaptation to variations in pressure presents a real problem to many different forms of life. Fish, for example, are exposed to a pressure of two atmospheres at a depth of only 34 feet below the surface of the water. The pressure at a depth of 2 miles, at which various species of fish have been captured, is approximately 300 atmospheres, or 4,600 pounds per square inch. Apparently, one of the chief compensatory adjustments required is an