THE FERTILISATION OF FLOWERS. 



331 



he did not realise the import of these markings in flowers until he 

 saw how much time bees lost, if honey which has been put out for 

 them is even slightly moved from its usual place. Whilst it forms an 

 allied subject of the most interesting description, to speculate upon 



FIG. 231. FLOWER AND STAMENS OF SALVIA. 



the remarkable changes in colour which some plants undergo, and 

 which, like the times of opening and closing, are doubtless related 

 to the visits of insects. Thus, we know of some flowers (Hibiscus] 

 which are white in the morning, of a pale rose hue at mid-day, and 

 exhibit a bright rosy red colour in the evening. Many flowers 

 change their hues as the petals wax old and tend to fall off ; and 



ti 



FIG. 232. FERTILISATION OF SALVIA. 



that such alterations of hue have a reference to insect-visits, and 

 attract, it may be, insects of different tastes and structure at different 

 periods, is by no means a far-fetched speculation. The presence of 

 bright colours in flowers has been shown to bear an important. rela- 

 tion to fertilisation, and necessarily, through this latter process, to 

 the development of such species of plants. Bright hues are, as a 



