42 SLEEP OF PLANTS. [CHAP. 



themselves ; by eight o'clock the flower is as fragrant 

 as before, the second set of stamens have rapidly 

 grown, their anthers are open, and the pollen again 

 exposed. By morning the flower is again " asleep," 

 the anthers are shrivelled, the scent has ceased, and the 

 petals rolled up as before. The third evening, again 

 the same process occurs, but this time it is the pistil 

 which grows: the long spiral stigmas on the third 

 evening take the position which on the previous two 

 had been occupied by the anthers, and can hardly fail 

 to be dusted by moths with pollen brought from 

 another flower. 



An objection to the view that the sleep of flowers is 

 regulated by the visits of insects, might be derived 

 from the cases of those flowers which close early in 

 the day, the well-known Tragopogon pratense, or " John 

 Go-to-bed at Noon," for instance ; still more, such 

 species as Lapsana communis, or Crepis pulchra, which 

 open before six and close again before ten in the 

 morning. Bees, however, are very early risers, while 

 ants come out later, when the dew is off; so that it 

 might be an advantage to a flower which was quite 

 unprotected to open early for the bees, and close 

 again before the ants were out, thus preserving its 

 honey exclusively for bees. 



Thus then I have endeavoured to show in a variety 

 of cases how beautifully flowers are constructed, so as 

 to secure their fertilisation by insects. Neither plants 

 nor insects would be what they are, but for the in- 

 fluence which each has exercised on the other. Some 

 plants, indeed, are altogether dependent on insects for 

 their very existence. We know now, for instance, that 



