Inflated Calyx. 125 



mouth of the corolla, try to get at the nectar, which 

 they smell^ inside the flowers, by biting a hole through 

 the leafy investments of the nectary and inserting their 

 proboscis. This they are especially prone to do when 

 the passage which leads to the nectar is not a perfectly 

 open one, but is covered in by projecting parts that 

 must be pushed aside before access can be obtained. 



* I have already briefly alluded to the fact that it is by smell 

 that humble or other bees are attracted to the nectar. The clearest 

 evidence of this is furnished by those oases where the bees, usually 

 humble-bees, obtain the nectar in a manner prejudicial to the 

 plant ; as occurs, for instance, with species of Aconitum, Gentiana, 

 Bhododendron, and Pedicularis ; flowers to which I shall have to 

 come back in the final chapter. Not only the nectar, but the 

 parts that secrete and store it, are quite out of sight of the humble- 

 bees, even when they have settled on the flower ; and yet they 

 proceed forthwith to bite a hole through the perianth at the precise 

 spot which ofiEers the shortest road to the nectar. The nectar of 

 flowers, it is true, makes as a rule no impression on our olfactory, 

 nerves ; but this by no means excludes the possibility of its being 

 perceptible to insects even at some distance. When Sphinx con- 

 volvuli is seen flying with the rapidity of an arrow to the flowers 

 of Lonicera etrusea or Caprifolium, nay more, directing its flight 

 towards them from a distance at which they must be quite out of 

 its range of vision, it cannot be doubted that it is the perfume from 

 the corolla, which even our olfactory nerves can recognise at some 

 distance, that has furnished the attraction ; and we must draw 

 the same inference when we see the same phenomena with flowers 

 that contain nectar and yet are to our senses without scent and 

 without attractive coloration. Place yourself near a hedge where 

 the beea are swarming about the open flowers of Ampelopsis 

 hederacea, and you will soon be convinced of this. The observations 

 to be recorded in the next section, respecting the flowers of 

 certain Caryophyllacese, render it, moreover, highly probable that 

 the perceptibility of the nectar by certain insects is often subject 

 to some condition of periodicity ; just as there are many flowers 

 whose corollas develop a perfume perceptible to oilr own olfactory 

 nerves only at certain fixed hours in the day. 



