226 THE POPULAR SCIENCE MONTHLY 



plant depends on one species only to those for whom any insect that can 

 carry pollen at all will serve. An illustration of a dependent plant is 

 the Yucca which is visited by a little white moth, a Pronuba, which 

 proceeds in its work as deliberately and purposefully as if it realized the 

 importance of every step in the process. Another of still greater inter- 

 est is that of the edible Smyrna fig, which depends upon Blastophaga 

 for its fruit development. It is a case where the establishment of a 

 horticultural interest depended upon the possibility of introducing with 

 the fruit its specific pollinator as well. 



The relation of bumble-bees to red clover is so well understood now 

 that it is not really necessary to do more than mention it, and in general, 

 the most effective pollinators are found among the bees, because they, 

 more than any other insects, are structurally adapted for the gathering 

 and transportation of pollen. Not only are the mouth structures 

 adapted for getting deep into the flower cups but the hairy covering 

 itself is modified so that it holds the grains dislodged as the insect 

 moves among them. 



To be sure butterflies and moths are also of use, and the butterfly 

 tongue is well adapted for its purpose of reaching down and lapping 

 nectar from concealed nectaries. Some of these tongues indeed are 

 so developed as to permit the insects to feed while on the wing and 

 to get into depths beyond the reach of less favored species. 



(To be concluded) 



