43 



each of which contains two bright yellow pollen masses connected together at the end 

 next to the hinge by a viscid drop ; the pair is, therefore, drawn out at once by any body 

 touching this viscidity. 



That some animated agent is required to affect the pollination is manifest from the 

 fact, stated before, that the anther never opens of itself, not even when the flower is 

 violently shaken. There is indeed no free nectar, but the basis of the lip and of the column, 

 which are connate, are thickened around a small depression which seems to correspond to 

 the spur of the other genera, and are as if swollen with juices. To insects knowing how 

 to draw from this store, the winged column offers a most convenient stage while sucking 

 the sweets. Then the anther is behind them and the pollinia must become attached to 

 their legs as is the case with the milk-weed. 



Though I paid many visits to a Calopogon plot, and noticed many anthers with 

 empty cells and many stigmas pollinised, I only once saw an insect visit a flower. It 

 was a humble-bee as it was just alighting on a column, its head towards the labellum ; 

 but unfortunately it flew away frighted by my presence, without having raised the 

 anther. However, it was easy to understand that so large an insect must by its weight 

 bend down the column, when the edge of the swelling at its apex would thus offer a sure 

 foothold. In its movements, the bee cannot but invert the lid of the anther, and then 

 often, if not always, the pollinia will be fastened to a leg and carried either to the contig- 

 uous stigma or to that of some other flower. Humble-bees are, moreover, known to 

 puncture juicy parts of flowers, as I shall have occasion to mention later, and they have 

 a well-known trick with long honey-tubes, to save themselves trouble, of biting them 

 through from the outside. This may frequently be seen in the flowers of Linaria 

 vulgaris, the common Toad-flax, and the Garden Antirrhinum. 



By holding successively a house-fly and then a meat-fly over the anther of a Calopogon, I 

 saw that the former was no4 strong enough to produce any effect on the lid, while the 

 latter lifted it without difficulty, and soon had the pollinia attached to its legs ; in its 

 struggles to free itself, the insect then brought them against the stigma, which retained 

 them. Self-fertilisation seems thus not to be so well guarded against as in the case of 

 Pogonia. 



Tribe Ophryde.#:. — {Orchis, Habenaria.) 



In this tribe, the anther is adnate to the apex of the column. Its dehiscence takes 

 places by a slit along the whole length of the two cells, which contain each a granular 

 pollinium. The caudicles into which the pollinia are produced, become then connected 

 with the two glands of the rostellum. In the genus Orchis these glands are protected by a 

 pouch, and are contiguous, coalescing even into one; in the genus Habenaria, they are on 

 the contrary naked and more or less distant from each other. As soon as they adhere to 

 any object, they flatten out into a disc, which has generally the remarkable property of 

 contracting in a peculiar direction, and in about half a minute or more of time, causing 

 to bend down from an erect position to a nearly horizontal one. If now the object loaded 

 with them is replaced in a flower in the same position as before, the pollinia strike not 

 against the anther cells, but exactly against the viscid stigma situated lower down, and 

 in Habenaria (in consequenee of a simultaneous movement of rotation) between the cells. 

 Darwin was the first to describe this movement of depression, and he understood all the 

 details as conducive to regular fertilisation, but in the English Orchises the spur is devoid 

 of honey, and he was long unable to discover what could attract the absolutely necessary 

 insects. "Sprengel, who supposed that the pollinia were applied to the stigma of the same 

 flower, suggested that the insect visitor came in search of honey, and on finding none, 

 passed on to some other kind of flower. But it- was essential for Darwin's theory that the 

 insect visitor should visit a number of the flowers in succession, and Darwin suggested 

 t&at possibly the insects pierced the delicate tissue of the spur and sucked the included fluid, 

 My own direct observations have confirmed this view, as well as every detail of the rest of 

 Darwin's account." (Miiller.*) Hive-bees and humble-bees, also an Empis, a dipterous fly. 

 have been seen in Europe to pierce the inner wall of several kinds of Orchis with the 



* See also Am. Nat., pp. 280 and following. 



