420 



GENERAL PRINCIPLES 



tion for pollination. The insects are often as much modified. 

 The worker bee has special organs for carrying pollen, the Moth 

 has a long proboscis for reaching into the extremely deep necta- 

 ries of certain flowers and thePronubahas developed a special in- 

 stinct for pollinating the Yucca, which is as much a part of the 

 insect as are its legs and wings. In many cases both plant and 

 flower are so modified with respect to each other that one can- 

 not exist without the other. 



FIG. 257. FIG. 258. 



FIG. 257. Pronuba yuccasella in the flower of the Yucca. (From Folsom 

 after Riley.) 



FIG. 258. Female Pronuba getting pollen from the anther of Yucca. (From 

 Folsom after Riley.) 



854. Care of Young. The food stored up in seeds and in eggs 

 is not the only kind of provision made for the young of the next 

 generation. Birds feed the young until they are able to hunt 

 food for themselves, and the young of Mammals are fed for some 

 time from the secretions of the mammary glands of the female. 

 But many more special adaptations occur. To mention only 

 one from the plants: The mangrove trees grow in shallow 

 water, but the seeds are not allowed to fall and drown or be 



