75 WAYSIDE AND WOODLAND BLOSSOMS. 



secreted. At the top of this spur, at the back, is the stigmatic 

 surface, and above it protrudes a fleshy knob, called the 

 rostellum, which supports the anther. This organ consists of 

 two lobes, side by side, which open in front, and reveal in each 

 a mass of pollen grains tied together by elastic threads and 

 attached to a slender foot-stalk with a sticky base. This is a 

 tedious description, though we have made it as brief as pos- 

 sible. The reader shall see the reason for it if he will conduct 

 a little experiment. We may premise that these orchids are 

 fertilized by long-tongued insects, who suck the juice through 

 the tender skin lining the spur. 



Now for the experiment. Take a finely-pointed pencil, 

 which we will pretend is the head and tongue of a humble-bee 

 in search of this sweet juice. We push the point gently down 

 the spur, when a part of the pencil touches against the rostel- 

 lum and presses it down, touches lightly the viscid feet of the 

 pollen masses (pollinia)^ and as the pencil is withdrawn both 

 come with it, and stick out from it like a pair of horns. Be 

 careful to hold the pencil in the exact position it now occupies, 

 and watch. The heavy heads of the pollinia are drooping 

 forward, but after a few minutes they cease to fall lower. Now 

 push the pencil into this other flower. The pollen-masses go 

 directly to the stigma^ and some of the pollen is detached. 

 If you are watching where orchids grow it is no uncommon 

 thing to see insects flying around with these pollinia attached 

 to their heads or tongues like a pair of horns. 



It will be seen to be impossible for the pollen to fall upon 

 the stigma of the same flower, and from its elastic attachments 

 it is impossible that it should be carried by the wind to 

 another flower, so that insect agency is here an absolute 

 necessity. 



