Page:Darwin - The various contrivances by which orchids are fertilized by insects (1877).djvu/59

. I. and I determined to examine O. morio rigorously. As soon as many flowers were open, I began to examine them for twenty-three consecutive days: I looked at them after hot sunshine, after rain, and at all hours: I kept the spikes in water, and examined them at midnight, and early the next morning: I irritated the nectaries with a bristle, and exposed them to irritating vapours: I took flowers which had lately had their pollinia removed by insects, of which fact I had independent proof on one occasion by finding grains of some foreign pollen within the nectary; and I took other flowers, which judging from their position on the spike, would soon have had their pollinia removed; but the nectary was invariably quite dry. After the publication of the first edition of this work, I one day saw various kinds of bees visiting repeatedly the flowers of this same Orchid, so that this was evidently the proper time to examine their nectaries; but I failed to detect under the microscope even the minutest drop of nectar. So it was with the nectaries of O. maculata at a time when I repeatedly saw flies of the genus Empis keeping their proboscides inserted into them for a considerable length of time. Orchis pyramidalis was examined with equal care with the same result, for the glittering points within the nectary were absolutely dry. We may therefore safely conclude that the nectaries of the above-named Orchids neither in this country nor in Germany ever contain nectar.

Whilst examining the nectaries of O. morio and maculata, and especially of O. pyramidalis and hircina, I was surprised at the degree to which the inner and outer membranes forming the tube or spur were separated from each other,—also at the delicate nature of the inner membrane, which could be penetrated very easily,—and, lastly, at the quantity of fluid contained