Abstract
1. The axopods of Actinophrys sol are caused to collapse by the application of high hydrostatic pressures. 2. Axopods grow out again on release of pressure or on reduction of pressure below a certain critical value. 3. Temperature and pressure act in opposition as regards the outgrowth and maintenance of axopods. At 15° C., the average critical value for the restoration of axopods is about 3500 p.s.i. (207 atm.). An increase of temperature by 10° C. counteracts an increase in pressure of 1200 p.s.i. (82 atm.).