ii.] THE SLEEP OF FLOWERS. 39 



from snakes and other enemies. As instances of this kind, 

 I may mention the common Snowdrop, and the Cyclamen. 

 Many flowers close their petals during rain, and this, 

 is obviously an advantage, since it prevents the honey 

 and pollen from being spoilt or washed away. I have 

 elsewhere suggested that the so-called " sleep " of flowers 

 has reference to the habits of insects, on the ground 

 that flowers which are fertilised by night-flying insects 

 would derive no advantage from being open in the day ; 

 while, on the other hand, those which are fertilised by 

 bees would gain nothing by being open at night. I 

 confess that I suggested this with much diffidence, but it 

 may now, I think, be regarded as well established. 



Silene nutans (Fig. 34), the Nottingham catchfly, is a 

 very instructive species from this point of view, and 

 indeed illustrates a number of 

 interesting points in the relations 

 between plants and insects. Its 

 life history has recently been well 

 described by Kerner. The upper 

 part of the flowering stem is 

 viscid ; from which it has derived 

 its English name, the Nottingham FIG. u.-sucne 

 catchfly. This prevents the access 



of ants and other small creeping insects. Each flower 

 lasts three days, or rather three nights. The stamens 

 are ten in number, arranged in two sets, the one set 

 standing in front of the sepals, the other in front 

 of the petals. Like other night flowers, it is white, 

 and opens towards evening, when it also becomes ex- 

 tremely fragrant. The first evening, towards dusk, the 



