LIFE HISTORIES OF FAMILIAR PLANTS 



Fig. 29 (Plate 19), they meet with disappointment, 

 for the arum contrives to induce the midges to 

 enter the bloom before its pollen and nectar are 

 mature. So, when the insects reach the base of 

 the bloom and find no nectar there, they have 

 plenty of time to sober down and perhaps repent 

 the foolishness of their past orgy. In fact, this 

 period of fasting after one feast often lasts so 

 long that they become really hungry. 



Of course, you will ask : Why then do not the 

 flies leave the bloom ? They undoubtedly would 

 if they could, and they travel up and down the 

 central axis many times, doubtless with that 

 intention, but when they reach the bristles in the 

 narrowed neck of the bloom they find that, 

 although they could travel down them freely 

 enough when they entered, yet they cannot return 

 the same way, for the bristles point downwards 

 and form a perfect barrier against their leaving. 

 Indeed, they are prisoners until the arum chooses 

 to release them. There is often ample room for 

 such tiny flies to travel up the sides of the hood, 

 and so miss the bristles, but they make no attempt 

 to escape in this manner ; it may be that the hood 

 is too steep and smooth for them to climb. 



So the midges crawl about within in durance 

 vile, and keep increasing in numbers as new 

 visitors arrive. Meanwhile, however, the lower 

 female flowers arrive at maturity, and the top of 

 each carpel or ovary develops a sticky stigma. 

 Amongst these gummy surfaces the tiny flies 

 wander in search of the nectar which they need 



40 



