POLLINATION MECHANISMS 93 
nectar is stored. The stamens, only two of which are 
developed, have each a hinge near the top, the part 
above the hinge being like a curved rod supported 
near its middle. These two curved rods stand nor- 
mally in a vertical position, so that their lower ends 
partly block the entrance to the tube; the pollen is 
borne at their upper ends. Should a bee insert its 
head down the tube in search of nectar, it pushes the 
lower ends of the hinged rods upwards, with the 
Fic. 18, —FLOWER AND FRUIT OF LINARIA PURPUREA. #, 
result that their upper ends swing downward against 
the bee’s back, dusting it with pollen just at that part 
of its body which, if the bee should visit a rather older 
flower, would come in contact with the stigma, the 
slender stalk of which (the style) increases in length 
during the period of flowering, and is in consequence 
the more liable to be encountered. 
Only one more instance can be referred to, which 
can be tested by the reader any summer day wherever 
