Ad hoc structural model of the β-carotene microparticle system on basis of the presented AUC results. The different color of the samples does not originate from the intraparticular coexistence of H- and J-aggregates as assumed before (Fig. 2) (Auweter et al. 1999) but instead separate particles contain pure H- or J-aggregates and the concentration ratio between these particles determines the colour of the final sample. Note the difference to Fig. 2