46 . NATUKE STUDY 



two cells of pollen which are located on each side of the 

 stigma and are more or less separated from each other in 

 the different species. In fact, the genus has recently been 

 cut up by Dr. Rydberg, into seven genera. Whether he 

 is right or not is a matter for the systematists to decide. 

 Each separate, club-shaped mass of pollen (anther sac) is 

 narrowed toward the base into a slender thread (caudicle) 

 and to this is attached a disc or gland of ver}' viscid mat- 

 ter. The use of this sticky gland will soon be apparent. 

 We will suppose the insect to alight on the lip and to crawl 

 toward the nectary at the base of it. As he presses forward 

 to insert his proboscis some part of his head will strike 

 against the glands. These will adhere to him with such 

 tenacity that when he backs out of the flower he will tear 

 the whole pollinium off and fly awa}^ with it. When he 

 enters another flower, if ever^-thing works right, he will 

 thrust the large end of the pollinium against the stigma. 

 When he withdraws, part of the pollinium will adhere to 

 the viscid stigma, the delicate membrane which encloses 

 the pollen will be ruptured and some of the pollen will re- 

 main on the stigma. In this case the only harm that comes 

 to the insect is the inconvenience of lugging around one or 

 more pollinia which must to him appear quite large and 

 burdensome. Sometimes these impediments become at- 

 tached to the eye, sometimes to other parts of the head, 

 sometimes to the proboscis. A proboscis encumbered with 

 half a dozen or more of these bundles must be nearly use- 

 less and its owner in danger of starvation. 



But this is not the whole story of the pollinia. It might 

 happen that they would not be in the right position to strike 

 the stigma of the next flower ; in fact, when they first ad- 

 here to the insect they are placed at such an angle that 

 they would not strike it, and all contrivances up to this 

 point would have been evolved in vain. By a refinement 

 of specialization so wonderful that it would scarcely be cred- 



