FLORAL MECHANISMS 95 



retain their pollen within. Then the stigma grows, 

 elongating its style, and shoving forward its curious, 

 star-shaped stigma, which, acting like a piston in 

 a cylinder, gradually pushes before it the charge of 

 pollen. 



Now of course the pollen must escape, so it 

 emerges through a small opening at the outer end 

 of the stamens, a little at 

 a, time. If we take away 

 the supply more is pushed 

 out, reminding us of a 

 minute sausage-stuif er at 

 work, squeezing out its 

 meat. When at length 

 all the pollen has gone, 



. i PALE SPIKED LOBELIA 



out comes the stigma, 



and becomes adhesive and ready for the touch of 



some pollen from another flower. 



CARDINAL FLOWER Lobelia cardinalis 

 August-Sept. 



This flower supplies its pollen in small instal- 

 ments in exactly the same manner as the pale spiked 

 lobelia, and it is more convenient to study because 

 its working parts are so much larger. 



We might almost assume that the piston-and- 

 cylinder scheme had been invented by the lobelias, 

 and then the idea had been appropriated by the 



