In the experiments of Charles and Francis Darwin, which parts of the seedlings were shown to be sensitive to light?

Question

Quizplus · Accepted Answer

Charles and Francis Darwin showed that only the extreme tip of the coleoptile was sensitive to light. They observed that when the tip of the coleoptile was covered, the seedling would grow straight up regardless of the direction of the light source, while leaving the tip exposed to light caused the seedling to bend towards the light source.

In the Experiments of Charles and Francis Darwin, Which Parts