The phytoflagellate, Euglena gracilis var Z , maintained in a chemically defined culture medium, was subjected to various high hydrostatic pressures (10,000-15,000 psi) a t various temperatures (15" 20" and 25Β°C). The effects on form stability, locomotion, euglenoid movement and flagellatory activity were observed at various times after the application of pressure.
The pressure-temperature relations of form stability clearly show that the supporting gel structures of the cell, presumably the peripheral gelated cytoplasm and the pellicle, may be identified as Type I1 systems i n the Freundlich classification, since they undergo solational weakening with increasing pressure and with decreasing temperature. The gelational state of these structures appears to be unusually high, however, since at each given temperature, a n usually high intensity of pressure is required to produce a n observable loss of stability, i.e. a rounding up of the normally elongate cells.
Flagellatory movement continued even a t the highest pressure, but locomotion was abolished i n all rounded and partly rounded individuals. Euglenoid movement ceased a t relatively lower pressure (about 10,000 psi).
The rounding of the euglena, even a t maximum pressures, was not accompanied