64 THE COLOURS OF FLOWERS. 



ones, besides being deeply marked with belts and spots 

 of dappled colour. In the allied Tropcsolum (Fig. 23) or 

 Indian cress (the so-called nasturtium of old-fashioned 

 gardens — though the plant is really no more related 

 to the water-cress and other true nasturtiums than we 

 ourselves are to the great kangaroo) this tendency is 

 carried still further. Here, the calyx is prolonged 

 into a deep spur, containing the honey, inaccessible to 

 any but a few large insects ; and towards this spur all 

 the lines on the petals converge. Sir John Lubbock 



Tig. 23. — Flower of Indian cress {Tropceoluttt waJMs). with one sepal prolonged into 

 a honey-bearing spur ; orange and yellow. 



observes that without such conventional marks to 

 guide them, bees would waste a great deal of time in 

 bungling about the mouths of flowers ; for they are 

 helpless, blundering things at an emergency, and 

 never know their way twice to the same place if any 

 change has been made in the disposition of the 

 familiar surroundings. 



The readiness with which the Geraniacece pass into 

 irregular forms in Pelargoniiim and in the balsam 

 genus {Impatiens), in itself shows that they are a fairly 

 advanced family, and explains the common appear- 



