78 SCIENCE PRIMERS. [xx. 



far down the corolla tube, and the stigma high up at 

 its mouth, the other has stamens high up the tube and 

 the stigma far down; both have honey at the very 

 bottom of the corolla tube. When a bee visits a 

 short-styled flower, it thrusts its proboscis to the 

 bottom and, withdrawing it, brings away some pollen 

 at its base. If it then visits another short-styled 

 flower it cannot fertilize it, and only takes more pollen 

 away ; but if it visits a long-styled flower it must de- 

 posit pollen on its stigma, that being at the mouth of 

 the corolla. If, on the other hand, the bee first visits 

 a long-styled form of primrose the operation is reversed, 

 it will then carry away pollen upon the tip of its 

 proboscis and deposit this on the stigma of the next 

 short-styled flower it visits. 



123. In the common orchis the anther is placed 

 above the stigma, which is a hollow viscid cavity in 

 front of the flower, at the base of the lip, and the lip 

 is produced into a long tube full of honey. A bee 

 seeking honey thrusts its head against the anther, and 

 in so doing detaches one or both of the two sticky 

 glands to which two club-shaped masses of pollen are 

 attached ; these it carries away on its forehead, in 

 an erect position. So long as the pollen masses 

 are erect on the bee's head these do not reach the 

 stigma of any other flower that it visits ; gradually, 

 however, as the sticky gland contracts, the pollen 

 masses incline forward and assume a horizontal 

 position, in which they must touch the stigma of 

 the next flower the bee visits, when the greater 

 stickiness of the stigma detaches some or all the pol- 

 len from the bee's head and fertilizes the flower. 

 Further, in some cases it takes so long for the pollen 



