THE FLOWER AND THE BEE 



length of 11 inches. It seemed impossible at the time of 

 the discovery of this plant that there should be in existence 

 a moth with a tongue long enough to consume all of the 

 nectar, but such a moth was later actually found. To re- 

 move the pollen masses it must thrust its long proboscis 

 into the nectary up to its very base. If these great moths 

 were to become extinct, then assuredly Angroecum would also 

 become extinct, for smaller moths are unable to remove the 

 poUinia. On the other hand, as Darwin states, there will 

 always be an inch or more of nectar at the base of these long 

 nectaries safe from the depredations of other insects, upon which 

 the moths are probably largely dependent. Thus the destruc- 

 tion of either the plant or the moth would be fatal to the sur- 

 vivor. The tongues of the moths tend continually to increase 

 in length in order that they may drain the last drop of nectar, 

 while the nectaries which are long enough to compel the moths 

 to insert their tongues up to the very base will be the best 

 fertilized. Thus there is a race between the moths and the 

 plants, in which AngrcBcum has triumphed, for it still flourishes 

 abundantly in the forests of Madagascar. 



There was undoubtedly a time in the history of butterfly 

 and moth flowers when the nectar was less deeply concealed 

 than at present and was accessible to bees. Concealment of 

 the nectar was at first beneficial by shutting out marauding 

 beetles and flies. And at this point the lengthening of the 

 nectaries, or corolla-tubes, should have stopped, for bees are 

 the most valuable of pollinators, and as a general principle 

 it is a disadvantage for a flower to be dependent on a single 

 species or genus of insects for pollination. But variation in 

 the direction of increased length of the nectaries once started, 

 the impulse still continued, and the tongues of the visiting 

 moths and butterflies lengthened correspondingly. The ne- 



158 



