LAW OF P/WGRESSIVE COLOURATION, 



55 



sage (Fig. 19), and basil, which it need hardly be said 

 are great favourites with bees. Ground-ivy [Nepeta <^le- 

 chomd) is bright blue ; catmint {Nepeta cataria), pale 

 blue ; Prunella, violet-purple ; and common bugle 

 {Ajtiga reptans), blue or flesh-colour. Many of the 

 others are purple or purplish. It must be added that 

 m this family the flowers are very liable to vary 

 within the limit of the same species ; and red. white, 

 or purple specimens are not uncommon in many of 

 the normally blue kinds. 



Fig. 19 — Flower of sage {Salvia) visited by b^e ; blue. 



The Scrophularmecs^n^ other allied irregular tubular 

 families are mostly spotted, and so belong to a later 

 stage of our inquiry ; but even amongst this group, 

 the Veronica genus has almost always pure blue 

 flowers ; foxglove {Digitalis purpurea) is purple; and 

 most of the Kroomrapes {Orobanchacece) are more or 

 less bluish. Blue and lilac also appear abundantly 

 in spots or stripes in many species of Linaria., in 

 Euphrasia^ and in other genera. 



We have given so much consideration to the Dico- 

 tyledons that the relatively simple and homogeneous 



