234 A BOOK OF INSECTS 



The flowers are very large, and the labellum, instead of 

 forming a spur, is converted into a bucket, into which 

 liquid drips from two special glandular appendages. This 

 fluid, though slightly sweet, does not deserve to be called 

 nectar ; nor does it attract insects — this office being 

 served by fleshy, succulent portions of the labellum itself 

 which certain humble-bees are eager to eat. When the 

 bucket is full, the fluid escapes through a kind of spout, 

 which is over-arched by the column bearing the stigma 

 and pollen-masses. Humble-bees congregate upon the 

 labellum, often in considerable numbers ; and in their 

 struggles to get a share of the coveted dainty which the 

 flower provides, some of them fall into the bucket. 

 When a bee gets a ducking it can only escape from its 

 unpleasant predicament by creeping through the over- 

 flow spout, and in so doing it must needs pass beneath 

 the column. The first bee to do this gets the pollinia 

 glued to its back. As soon as its wings are dry, it flies to 

 the same or another flower, where sooner or later it gets 

 another wetting, and goes through the whole distressing 

 process of its inglorious exit once again. This time, 

 however, it carries pollen-masses which, as the insect 

 creeps through the spout, come into contact with the 

 stigma. In this way pollination is effected. " There 

 cannot be the least doubt," concludes Darwin, " that the 

 fertilisation of the flower absolutely depends on insects 

 crawling out through the passage formed by the extremity 

 of the labellum and the over-arching column. If the 

 large distal portion of the labellum or bucket had been 

 dry, the bees could easily have escaped by flying away. 

 Therefore we must believe that the fluid is secreted by 

 the appendages in such extraordinary quantity, and is 

 collected in the bucket, not as a palatable attraction for 

 the bees, as these are known to gnaw the labellum, but 



