20 PLANT LIFE. 



long suction tube, often, indeed, much longer than the 

 insect. 



In the Bee all three pairs of jaws are employed. 

 The second pair are strong biting and masonry tools, 

 and can be pushed out a short distance. The third pair 

 can be pushed out still further, and they carry two side 

 flaps. The fourth pair has also two side-pieces, and a long 

 hairy tongue in the centre. Whilst sucking honey the 

 two flaps of jaws No. 3 and the two side-pieces of jaws 

 No. 4 fit over the floor of the mouth parts and form a 

 suction tube about 6 millimetres long. Before flying the 

 whole proboscis is drawn in and then folded so as to be 

 neatly packed away under the head. 



These modifications in the structure of insects are 

 undoubtedly a result of their flower-visiting habits. The 

 effects which insects have had upon flowers is well shown 

 in, e.g. the "Bluebeard" Salvia. In this species, the 

 upper bracts, which are about f inch in length, are a rich 

 blue-purple or typical bee-colour. After flying to this 

 very conspicuous centre of attraction, the bee notices 

 the small patches of bright blue on the upper lip of the 

 flower some distance below the bract. This blue is set 

 off by white hairs on the upper lip and yellow on the 

 lower. Thus, in addition to the two-lipped corolla, the 

 peculiar Salvia stamens and other arrangements for 

 insects, four distinct colours are contrasted and arranged 

 in an evidently intentional manner. 



But obviously the bee cannot produce colour inside 

 the flower. How these different tints have been formed 

 remains quite unknown. The existing theories upon the 

 subject are so weak and so indefinite, that they have to 

 be covered up and obscured in a very laboriously manu- 

 factured and imperfectly understood terminology. It is 

 well known, however, that flower-colour is much more 



