424 



HUTCHINSON'S POPULAR BOTANY 



FIG. 527. HEMLOCK STORK'S-BILL 

 (Erodium cicutarium). 



\Vith seven-spotted lady-bird clinging to a petal which its 

 weight has dislodged. 



byj Dr. Ogle that in flowers which 

 are cross-fertilized by insects, 

 Nature does not hold out her baits 

 one minute sooner than necessary. 

 " The brilliancy, the scent, and the 

 nectar are only furnished when the 

 flower is ready for its guests and 

 requires their presence ; just as a 

 thrifty housewife lights her candles 

 when the first guest is at the door. 

 The mature bud is furnished with 

 no such attractions." 



We have seen that Darwin's 

 pronouncement that '' Nature ab- 

 hors self-fertilization," though not 

 yet recognized (like Newton's law 

 of gravitation or Boyle's law of the 

 pressure of gases) as an established law of natural science, has yet some 

 striking facts to support it; and more of these facts will come before us 

 in the present chapter. "We have seen,vtoo, that the curious and often 

 minute correlations in certain flowers are in view of their cross-pollination 

 by insects ; and that the parts of the flower which sustain the weights, 

 strains, thrusts, etc., are admirably modified and strengthened, as though 

 to facilitate and encourage the guests by whose visits the crossing is to be 

 effected. Of this subject also the present chapter will furnish additional 

 illustrations. 



Yet it must not be thought that all cross-pollinated flowers are so careful 

 of their guests. In some instances it is really surprising that the visitors 

 remain at all, so little are they encouraged. Watching one day some seven- 

 spotted ladybirds (Coccindla septempunctata) licking honey from the pretty 

 rose-pink flowers of the Hemlock Stork' s-bill (Erodium cfoutarium), Hermann 

 Miiller met with an amusing illustration of this fact. While seated on a petal 

 the insect would apply its mouth to one of the nectaries at the base ; and 

 then all at once the petal would break off, and either precipitate the beetle 

 to the ground or leave it clinging to the next petal. " In the former case it 

 would keep on its way round the flower, and perhaps pull off all five petals, 

 one after another ; but when it fell it was always at once on its legs again, 

 running to another stalk of the same plant to climb up anew. I saw," adds 

 this careful observer, " one beetle fall four times to the ground without 

 growing wiser by experience " (fig. 527). 



How irritating, again, must be the treatment offered to the gnat- 

 pollinators of the Aristolochias, who (as we were seeing in another chapter) 

 are held prisoners in the blossoms for a period not far short of sixty hours! 

 Much the same sort of thing goes on in the flowers of the Indian stove- 



