Page:On the Various Contrivances by Which British and Foreign Orchids are Fertilised by Insects, and on the Good Effects of Intercrossing.djvu/14

 therefore to the seeding of O. pyramidalis; whereas, as we shall hereafter see, the Bee Ophrys is independent of insects.

I counted many spikes of O. latifolia, because, being familiar with the usual state of the closely-allied O. maculata, I was surprised to observe in nine nearly withered spikes how few pollinia had been removed. In one instance, however, I found O. maculata even worse fertilised; for seven spikes, which had borne 315 flowers, produced only forty-nine seed-capsules—that is, each plant on an average produced only seven capsules: in this case the plants had grown in greater numbers close together, forming large beds, than I had ever before observed; and I imagined that there were too many plants for the moths to suck and fertilise. On some other plants, growing at no great distance, I found above thirty capsules on each spike Orchis fusca offers a more curious case of imperfect fertilisation. I examined ten fine spikes from two localities in South Kent, sent to me by Mr. Oxenden and Mr. Malden: most of the flowers on these spikes were partly withered, with the pollen mouldy even in the uppermost flowers; hence we may safely infer that no more pollinia would have been removed. I examined all the flowers only in two spikes, on account of the trouble from their withered condition, and the result may be seen in the list, namely, fifty-four flowers with both pollinia in place, and only eight with one or both removed. We see in this Orchid, and in O. latifolia, neither of which had been sufficiently visited by moths, that there are more flowers with one pollinium than with both removed. I casually examined many flowers in the other spikes of O. fusca, and the proportion of pollinia removed was evidently not greater than in the two given in the list. The ten spikes had borne 358 flowers, but, in accordance with the few pollinia removed, only eleven capsules had been formed: five of the ten spikes bore not a single capsule; two spikes had only one, and one bore as many as four capsules. As corroborating what I have previously said on pollen being often found on the stigmas of flowers which have their own pollinia in place, I may add that, of the eleven flowers which had produced capsules, five had both pollinia still within their now withered anther-cells.

From these facts the suspicion naturally arises that O. fusca is so rare a species in Britain from not being sufficiently attractive to our moths, and consequently not producing a sufficiency of seed. C. K. Sprengel noticed, that in Germany O. militaris (ranked by Bentham as the same species with O. fusca) is likewise imperfectly fertilised, but more perfectly than our O. fusca; for he found five old spikes bearing 138 flowers, which had set thirty-one capsules; and he contrasts the state of these flowers with those of Gymnadenia conopsea, in which almost every flower produces a capsule.

An allied curious subject remains to be discussed. The existence of a well-developed spur-like nectary seems almost to imply the secretion of nectar. But Sprengel, a most careful observer, thoroughly searched many flowers of O. latifolia and of O. morio, and could never find a drop of nectar; nor could Kriinitz find nectar either in the nectary or on the labellum of O. morio, fusca, militaris, maculata, and latifolia. I have looked to all the species hitherto mentioned in this work, and could find no signs of nectar; I examined, for instance, eleven flowers of O. maculata, taken from different plants growing in different districts, and taken from the most favourable position on each spike, and could not find under the microscope the smallest bead of nectar. Sprengel calls these flowers "Scheinsaftblumen," or sham-nectar-producers; that is, he believes, for he well knew that the visits of insects were indispensable for their fertilisation, that these plants exist by an organized system of deception. But when we reflect on the incalculable number of plants which have existed for enormous periods of time, all absolutely requiring for each generation insect-agency; when we think of the special contrivances clearly showing that, after an insect has visited one flower and has been cheated, it must almost immediately go to a second flower, in order that impregnation may be effected (of which fact we have the plainest evidence in the large number of pollinia attached to the probosces of those moths which had visited O. pyramidalis), we cannot believe in so gigantic an imposture. He who believes in this doctrine must rank very low the instinctive knowledge of many kinds of moths.

To test the intellect of moths I tried the following little experiment, which ought to have been tried on a larger scale. I removed a few already opened flowers on a spike of O. pyramidalis, and then cut off about half the length of the nectaries of the six next not-expanded flowers. When all the flowers were nearly withered, I found that thirteen of the fifteen upper flowers with perfect nectaries had their pollinia removed, and two alone had their pollinia still in their anther-cells; of the six flowers with their nectaries cut off, three had their pollinia removed, and three were still in place; and this seems to indicate that moths do not go to work in a quite senseless manner.