AND CROSS-PEKTILIZE THEIR FLOWERS. 29 



down into the flower so as to press gently upon these disks for a moment ; then 

 withdraw it : the disks will stick fast, and the stalks with the pollen-mass be 

 drawn out of the anther. Now the tip of the finger or the pencil is just in 

 the position which the head of the large butterfly or moth would occupy when 

 its proboscis is thrust deep into the honey-tube. In draining the nectar from 

 the tube the insect's head is brought down close to its orifice, its large projecting 

 eye on one side or the other, or on both at once, is pressed against the sticky but- 

 ton ; and when the moth raises its head and departs, it carries away bodily one 

 or both of the pollen-masses. With these the next flowers visited may be ferti- 

 lized. 



58. Except by the insect's aid as a carrier, secured by this most elaborate and 

 wonderful contrivance, these Orchis flowers could never be fertilized. Close as 

 the pollen is to the stigma, it evidently cannot reach it by any ordinary chance. 

 And it would appear as if the obstacles were not eft'eotually overcome even when 

 a moth or butterfly is so ingeniously employed to convey the pollen from one blos- 

 som to another, which is plainly what is intended. For the position of parts is 

 such that when the pollen-masses are extracted by the moth's head, they will 

 stand poititing upwards and forwards, as shown in Fig. 20. The stalk is too stiff' 

 to allow them to subside by their own weight. So when the moth alights upon 

 the next flower and thrusts its proboscis down its honey-tube, the pollen-masses it 

 has brought would hit the anther, quite above the stigma, and eiFect nothing. 

 But all this is accurately provided for. As may be seen by watching the pollen- 

 masses when taken upon the point of a pencil, within from ten to thirty seconds 

 their stalk turns downward, as if upon a joint between it and the adhering disk, 

 bringing them into a position like that represented by a front view in Fig. 21. 

 Now the pollen-masses will accurately strike the stigma ! 



59. In some Orchises, and where this adjustment is needful, the pollen-masses 

 on the insect's head not only turn downwards but converge inwards, always in the 

 way and to the degree necessary for their striking the stigma. In the larger 

 Green Orchises, from which the illustrations are drawn, the sticky disk is almost 

 parallel with the stalk of the pollen-mass at its lower end, and attached to it by a 

 short intermediate joint, as shown in Fig. 18, and more magnified in Fig. 19. It 

 is nearly the same in the Yellow and the White Fringed Orchises, which flower 

 later in the season. In all these the disks face partly inwards, at considerable 

 distance apart, and are stuck to the eye of the butterfly that visits" them. In 



