Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/62

42 lower and first opened flowers. But this statement is completely contradicted by my observations previously given, from which it follows that very many of the upper flowers are fertilised; for instance, on a spike of O. pyramidalis with between fifty and sixty flowers, no less than forty-eight had their pollinia removed. Nevertheless, as soon as I learnt that Delpino still believed in Sprengel's view, I selected during the unfavourable season of 1875 six old spikes of O. maculata, and divided each into halves, so as to observe whether many more capsules were produced by the lower than by the upper half. This certainly was not always the case; for in some of the spikes no difference could be detected between them; in others there were more capsules in the lower, while in others there were more in the upper half. A spike of O. pyramidalis examined in the same manner produced twice as many capsules in the upper as in the lower half. Bearing in mind these facts and others before given, it appears to me incredible that the same insect should go on visiting flower after flower of these Orchids, although it never obtains any nectar. Insects, or at least bees, are by no means destitute of intelligence. They recognise from a distance the flowers of the same species, and keep to them as long as they can. When humble-bees have bitten holes through the corolla, as they often do, so as to reach the nectar more easily, hive-bees immediately perceive what has been done and take advantage of the perforations. When flowers having more than a single nectary are visited by many bees, so that the nectar is exhausted in most of them, the bees which afterwards visit such flowers insert, their proboscides only into one of the nectaries, and if they find this exhausted, they instantly pass on to another flower. Can it be believed that bees which