blossom Hosts Jini Insect Ciiests 



pointing the way to the nectar^'* — the spots, rings, 

 and converging Hnes on the petals constituting so 

 many guide-posts on the road to the nectary. 



THE WEAK POJXTS IX SPREXGEL'S THEORY 



Why was Sprengel's seeming victory an empty 

 one ? All that he stated about nectar, fragrance, 

 and color is true. These floral attributes are the 

 result of adaptation to insects, and have been ac- 

 quired for the special purpose of attracting them. 

 His theory fitted perfectly, too, the problem shown 

 in C, Fig. 2 and in Fig. 4. An insect could with- 

 out doubt fertilize such a flower with its own pollen, 

 but Sprengel's carefully noted facts showed only too 

 plainly that there were many other flowers incapable 

 of fertilizing themselves, and yet quite as incapable 

 of being fertilized in the way he had described. 



For instance, he was met at every hand by floral 

 problems, such as are shown at E and F, Fig. 2, 



example, possessed perfect nectar guides, and yet produced no nectar. 

 Sprengel supposed that these plants existed by an organized system 

 of deception, by leading the insects to suppose that nectar was con- 

 cealed in their depths, and thus inducing them to enter and perform 

 the service of the transfer of pollen, and then cheating them of their 

 reward. Darwin, however, showed that the nectar in Orchis morio 

 was contained in the upper and lower tissues of the corolla ; he also 

 explained the reason for this concealment. (See page 27.) Many 

 flowers produce quantities of pollen and little or no nectar. Such 

 flowers are especially adapted to pollen-gathering insects. 



* Evil-smelling flowers, like the trillium, attract carrion-loving 

 flies — the vile odor of these blossoms being the result of adaptation 

 to this special class of insects. 



