Page:On the Various Contrivances by Which British and Foreign Orchids are Fertilised by Insects, and on the Good Effects of Intercrossing.djvu/20

 superfluous, I covered up a plant under a net, so that some wind, but no insects, could pass in, and in a few days the pollinia had become attached to the stigmas; but the pollinia of a spike kept in water in a still room, remained free, suspended in front of the stigma.

Robert Brown first observed that the structure of the Bee Ophrys is adapted for self-fertilisation. When we consider the unusual and perfectly-adapted length, as well as the remarkable thinness, of the caudicles of the pollinia; when we see that the anther-cells naturally open, and that the masses of pollen, from their weight, slowly fall down to the exact level of the stigmatic surface, and are there made to vibrate to and fro by the slightest breath of wind till the stigma is struck; it is impossible to doubt that these points of structure and function, which occur in no other British Orchid, are specially adapted for self-fertilisation.

The result is what might have been anticipated. I have often noticed that the spikes of the Bee Ophrys apparently produced as many seed-capsules as flowers; and near Torquay I carefully examined many dozen plants, some time after the flowering season; and on all I found from one to four, and occasionally five, fine capsules, that is, as many capsules as there had been flowers; in extremely few cases (excepting a few deformed flowers, generally on the summit of the spike) could a flower be found which had not produced a capsule. Let it be observed what a contrast this case presents with that of the Fly Ophrys, which requires insect agency, and which from forty-nine flowers produced only seven capsules!

From what I had seen of other British Orchids, I was so much surprised at the self-fertilisation of this species, that during many years I have looked at the state of the pollen-masses in hundreds of flowers, and I have never seen, in a single instance, reason to believe that pollen had been brought from one flower to another. Excepting in a few monstrous flowers, I have never seen an instance of the pollinia failing to reach their own stigmas. In a very few cases I have found one pollinium removed, but in some of these cases the marks of slime led me to suppose that slugs had devoured them. For instance, in 1860, I examined in North Kent twelve spikes bearing thirty-nine flowers, and three of these had one pollinium removed, all the other pollinia being glued to their own stigmas. In another lot, from another locality, however, I found the unparalleled case of two flowers with both pollinia removed, and two others with one removed. I have examined some flowers from South Kent with the same result. Near Torquay I examined twelve spikes bearing thirty-eight flowers, and in these one single pollinium alone had been removed. We must not forget that blows from animals or storms of wind might occasionally cause the loss of a pollinium. In the Isle of Wight Mr. A. G. More was so kind as to examine carefully a large number of flowers. He observed that in plants growing singly both pollinia were invariably present. But on taking home several plants, from a large number growing in two places, and selecting plants which seemed to have had some pollinia removed, he examined 136 flowers: of these ten had lost both pollinia, and fourteen had lost one; so here there seems at first evidence of the pollinia having been removed by their adhesion to insects; but then Mr. More found no less than eleven pollinia (not included in the above cases of removal) with their caudicles cut or gnawed through, but with their viscid discs still in their pouches, and this proves that some other animals, not insects, probably slugs, had been at work. Three of the flowers were much gnawed. Two pollinia, which had apparently been thrown out by strong wind, were sticking to the sepals, and three pollinia were found loose in his collecting box, so that it is very doubtful whether many, if indeed any, of the pollinia had been removed by adhesion to insects. I will only add that I have never seen any insect visit these flowers. Robert Brown imagined that the flowers resembled bees in order to deter insects from visiting them; I cannot think this probable. The equal or greater resemblance of the Fly Ophrys to an insect does not deter the visits of some unknown insect, which, in that species, are indispensable for the act of fertilisation.

Whether we look to the structure of the several parts of the flower as far as hitherto described, or to the actual state of the pollinia in numerous plants taken during different seasons from different localities, or to the number of seed-capsules produced, the evidence seems conclusive that we here have a plant which is self-fertilised for perpetuity. But now let us look to the other side of the case. When an object is pushed (as in the case of the Fly Ophrys) right against one of the pouches of the rostellum, the lip is depressed, and the large extremely viscid disc adheres firmly to the object, and the pollinium is removed. Even after the pollinia have naturally fallen out of their cells and are glued to the stigma, their removal can sometimes be thus effected. As soon as the disc is drawn out of the pouch the movement of depression commences by which the