1 2 Flowers and their Unbidden Guests. 



the first day of floweriiig, had been smeared with pollen 

 from the outwardly dehiscing anthers, to stand on the 

 last day, at the final closing of the flower, on a level 

 with the stigma. Again, take those species of Pedicu- 

 laris, in which the upper petals form a beak-shaped 

 tube. At the end of the blossoming period ^ the dusty 

 pollen gets into this little tube, and then, in conse- 

 quence of an angular movement of the corolla which 

 happens at this time, rolls upwards through the tube 

 to the stigma, which stands close over the mouth. 

 This as before results in autogamy. But the whole 

 mechanism can only be successful if the above-men-; 

 tioned angular movement be of a definite strength, 

 which again is only possible if the corolla be uninjured 

 and undisturbed during the flowering period. 



In the blossoms of many Caryophyllaceae (which will 

 be treated of more fuUy on a future page), the filaments 

 of the stamens lengthen quite suddenly with the coming 

 on of evening. The anthers are thus brought forward, 

 above the tube of the corolla ; they open, and, owing to 

 the position they have now assumed, expose their pollen 

 in such a situation that insects, attracted to the flowers 

 by the nectar, must necessarily wipe it off, and, flying 

 elsewhere, carry it to another flower on the same plant. 

 If, at the time when the pollen is exposed in these 



^ [In the earlier period of flowering, Pedicularis has flowers 

 most ingeniously adapted for cross-fertilisation ; cf. Pop. Science 

 Bex,, 1870, p. 45, where I have described it. — Editok.] 



