An orchid was found with a nectary that was only accessible by way of a long, narrow tube, and Darwin predicted the existence of an insect pollinator with an almost equivalently long tongue.

• 随著一种需要藉由细长管状物才能吸取其花蜜的兰花的被发现，达尔文预测说，一定存在有一种传递花粉的昆虫，具有细长的口器。