POLLINATION BY BIRDS AND OTHER ANIMALS 87 



diclinous and the plants are essentially dioecious. The pistillate 

 syconia, which are called figs, contain only normal pistillate flowers 

 with rather long styles, while the staminate syconia, called caprifigs, 

 contain both staminate flowers and small, short-styled, pistillate 

 flowers, which are known as gall flowers. Pollination of the fig is 

 accomplished by the female wasps. The orifices of the syconia are 

 so nearly closed by overlapping scales that the wasps have great 

 difficulty in getting in and often tear off their wings in the process. 

 After a wasp has entered a pistillate syconium she creeps over the 

 flowers searching for a suitable place to lay eggs and while doing this 

 the pollen on her body is rubbed onto the stigmas. The styles of the 

 flowers are so long, however, that the w^asp is unable to reach the 

 ovaries with her ovipositor and so is unable to lay any eggs. She 

 cannot get out of the syconium, however, and soon perishes, but 

 the flowers, having been pollinated, continue their normal develop- 

 ment and the syconium matures into a fig. 



If, on the other hand, the wasp chances to enter a caprifig she 

 readily reaches the ovaries of the short-styled gall flow^ers and lays 

 her eggs there. She then perishes in the caprifig. When the eggs 

 hatch the young wasps feed upon the tissues of the gall flowers and, 

 when mature, the males eat then* way out of the ovaries in which 

 they hatched and into those occupied by the females. After mating 

 with the females the males soon die without leaving the caprifigs. 

 The females now become dusted with pollen, make their way to the 

 exterior, and fly to another syconium. Those that by chance enter 

 figs will effect pollination but will not leave any offspring, while those 

 that enter caprifigs will leave offspring but will not effect pollina- 

 tion. This symbiosis is obligate for both the plant and the insect yet 

 the course of the evolution that has brought about so strange a rela- 

 tionship can scarcely even be imagined. 



54. Pollination by Birds and Other Animals.— Next to insects, 

 birds are the most important pollinating animals. Bird pollination 

 seems to be more important in the southern hemisphere than in the 

 northern. In South America the numerous humming birds are 

 important pollinators while in Africa the sun birds are more impor- 

 tant. The characteristics of bird flowers are in general similar to 

 those that we are familiar with in bee flowers. 



A few cases of pollination by bats have been reported but neither 

 these nor any other mammals are important as compared with birds, 

 and more especially with insects, as pollinating agents. 



