THE FLOWEEING PLANT — FLOWEES 311 



necessary sketches. Make loHgitudinal sections 

 of the ovary to find pollen tubes penetrating the 

 ovule. 



Examine various flowers to answer the follow- 

 ing questions : Is the pollen set free at the time 

 the stigma becomes mature, which state is usually 

 shown by a viscid secretion on its surface ? Is the 

 pollen in such a position and of such structure that 

 it may fall or be bloAvn upon the stigma ? Do the 

 stamens grow in such a position or are they of 

 such shape that, if an insect were to alight upon 

 the flower or to enter it, some of the pollen would 

 be dusted upon or would adhere to his body ? Is 

 the pistil in such a position that a visiting insect 

 would rub against it ? If the flower secretes nec- 

 tar, is it in such a place that, in order to get it, 

 the insect must brush against stamens or pistil or 

 both ? Is the nectar freely exposed, or is it at the 

 bottom of a tube, out of the reach of all insects 

 except such as have a long proboscis, or is the 

 entrance to the place where the nectar is stored 

 guarded by hairs, bristles, etc. ? 



