34 



BIOLOGY AND HUMAN LIFE 



it originates (the stamen) to the seed-bearing organ (the pistil) 

 (see page 42). The bees and the butterflies represent two 

 groups that are most generally active in this process of pollena- 

 tion (see Chapter IV). This interdependence between insects 

 and seed-bearing plants is in some cases so great that certain 

 orchids are dying out because the insects necessary for pollena- 

 tion are not sufficiently abundant to insure seeds every year. In 



other cases insects in- 

 troduced in a new re- 

 gion cannot maintain 

 themselves because the 

 needed food plants are 

 not present. In our reg- 

 ular horticulture it hap- 

 pens occasionally that 

 trees or bushes in full 

 blossom fail to yield the 

 expected crop of fruit 

 because of the lack of 

 insects to insure pollen- 

 ation. This is why wise 

 farmers and orchard- 

 men so often maintain 

 hives of bees : even 

 where the honey itself 

 is not considered worth producing, the bees are worth having 

 because they insure abundant pollenation at the right time. 



28. Homology. The division of labor among the organs of 

 the bee is of course the same as that which we find in other in- 

 sects, or even in entirely different classes of animals such as our 

 own bodies ; but if we compare the insects already studied with 

 one another, we shall find that most of the functions are carried 

 on by corresponding organs in the different animals. Thus, the 

 locomotive organs in bees, butterflies, and grasshoppers are the 

 legs and wings, and in every case the position of the organ and 

 the general plan of structure are the same. If we examine the 



Fig. 15. Division of labor among ants 



Three forms of the Central American fighting ant 

 (C/ieliomyrmex nortoni): a, soldier; b, medium 

 worker; c, small worker 



