Some highly unusual features of a lipid-water liquid crystal are revealed byhigh pressure x-ray diffraction, light scattering and dilatometric studies ofthe lamellar (bilayer $L_{\alpha}$) to nonlamellar inverse hexagonal ($H_{II}$)phase transition. (i) The size of the unit cell of the $H_{II}$ phase increaseswith increasing pressure. (ii) The transition volume, $\Delta V_{bh}$,decreases and appears to vanish as the pressure is increased. (iii) Theintensity of scattered light increases as $\Delta V_{bh}$ decreases. Data arepresented which suggest that this increase is due to the formation of anintermediate cubic phase, as predicted by recent theoretical suggestions of theunderlying universal phase sequence.
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