108 Mr Giistav Mann on Fertilisation in [sess. li. 



however, I tried the following experiment : — I caught several 

 humble bees, hive-bees, and different kinds of fly, including 

 some blue-bottles, and put them along with the Orchid under 

 a bell-jar, and watched them. For the first two hours the 

 insects were rather excited, but after that they became quiet, 

 and a hive-bee entered the flower first. It alighted on the 

 labellum, and then moved towards the base of the labellum 

 until its thorax came to the region of the first yellow spot, 

 when suddenly the labellum tilted up, and the bee was 

 thrown with the back part of the head and the thorax against 

 the viscid matter, and by crawling backwards its head moved 

 the anther case. I did not see the pollen masses removed, 

 however, for I had used them for fertilising another flower in 

 which the pollinia had been defective. The blue-bottle came 

 next, alighted in the same way, and when it put out its pro- 

 boscis to try whether the yellow spot contained something 

 sweet, the labellum lost its balance, and came into a vertical 

 position; this seemed to frighten the blue-bottle, and it 

 quickly crawled, backwards. 



The stellate hairs of the labellum give it a certain strength, 

 combined with lightness. The yellow colour of the three spots 

 ser\'es to draw the attention of insects to this particular place, 

 and why we shall see shortly. While the epidermal bulgings 

 at the same time prevent the insect from slipping, when 

 the labellum is in a vertical position, in order to give the 

 insect a sure foothold, the pit-like depressions are developed 

 towards the apex of the labellum. It must be remembered 

 that the claws of the two posterior pairs of an insect's legs are 

 directed backwards, and being curved, will naturally go into 

 the pits and help the insect to crawl back till the heavier 

 parts of its body are outside the yellow spot in the middle 

 line of the labellum, when, of course, the labellum will fall 

 back into its horizontal position, and the pits being now 

 directed upwards, the insect will have no difficulty in with- 

 drawing its claws, and may fly to the next flower, where the 

 same thing will happen over again, only with the difference 

 that now one pollinium — or may be both pollinia — is pressed 

 into the viscid matter of the stigma, and so fertilises the 

 flower, while at the same time new viscid matter and the 

 pollinia of the second flowerwill be attached to tlie insect's head. 



There is no nectary in this flower, and it is my opinion 



