Figure 3: Microphotographs of ice crystals growing in birch pollen washing water.

(a) Ice crystal growth in pure sucrose solution (control). (b) Ice crystal growth in raw filtrate of birch pollen #A washing water after heating to 90 °C for three hours to increase concentration. (c) Consecutive microphotographs of an ice crystal growing in the presence of birch pollen #B washing water after two ice affinity purification cycles; see also the entire sequence in Supplementary Video S1. In all experiments very small cooling rates of −0.01 °C min⁻¹ were applied at temperatures just below the ice melting temperature to ensure that shaping originates from interaction with ice-binding molecules^4,44. Note that while the absolute size and growth rate of the crystals in the three experiments are not directly comparable due to variable starting conditions (size, solute concentration, temperature etc.), the shape of each crystal is representative for each experiment.