“…In principal, two possibilities are conceivable, i.e. the induction of intracellular crystallization by nucleating agents present within the cell (Toscano et al 1975;Franks & Bray, 1980;Franks et al 1983) and by extracellular ice (Mazur, 1965(Mazur, , 1966. Rasmussen et al (1975) and Franks and co-workers (Franks & Bray, 1980;Franks et al 1983) have employed an emulsion technique for suppressing extracellular crystallization and detecting the formation of intracellular ice by means of differential scanning calorimetry, but obtained inconclusive results: whereas yeast and human erythrocytes could be supercooled down to the homogeneous nucleation temperature (Rasmussen et al 1975), Franks and coworkers (Franks & Bray, 1980;Franks et al 1983) observed intracellular crystallization above the homogeneous nucleation temperature for yeast, erythrocytes and various culture cells indicating the presence of heterogeneous nucleators.…”