1 etiolated coleoptile;
2 decapitation: the extreme tip of the coleoptile is removed (1mm),
3 second decapitaion (2-4 mm),
4 removal of the primary leaf,
5 removal of tip;
6 Auxin-containing gelatine block is placed on one side of the amputed tip of the seedling,
7 tip always bent away from the side on which the gelatine block was placed.