stigma. This mechanical transfer of the pollen grain to the stigma 

 constitutes what is known as pollination. Cross pollination is said to 

 occur when the pollen of one flower is carried to the stigma of another 

 flower of the same kind. Without discussing the matter, we find that 

 in nature cross-pollination occurs in a large majority of plants, and 

 that by many devices self or dose pollination is prevented. 



Cross-pollination is effected in a large measure through two 

 agencies, tJie unnd and insects. 



If we examine wind-pollinated flowers, we find the following con- 

 ditions to exist:. 



1. Calyx and corolla absent or greatly reduced. 



2. Absence (ordinarily) of fragrance. 



3. Absence of nectar or honey. 



4. The development of an immense quantity of pollen. 



The reasons for these correlations are very evident. The wind is 

 an insensate agent; it "bloweth where it listeth," and its direction is 

 not changed by brilliance of color, delicacy of odor or presence of 

 nectar. So natiire wastes no energy in the development of useless 

 structures, and all the force thus saved is turned to the production of 

 large quantities of pollen grains. This great amount of pollen is 

 necessary because of the uncertainty of any large portion of it finding 

 its way to stigmas ready to receive it; and so these large quantities 

 stand merely as the index of the difficulty of the perpetuation of 

 species in wind-pollinated plants. 



In insect-pollinated flowers, however, we have a sentient agency, the 

 insect, and as we examine the flowers we find the following correla- 

 tions: 



1. Development of color. 



3. Development of fragrance. 



3. Development of nectar. 



4. Extremely varied forms. 



5. A reduced amount of pollen. 



It is scarcely necessary to speak in detail of these correlations. 

 Color and fragrance serve largely, doubtless, to enable the insects to 

 readily find the plants which produce their favorite food. We must 

 remember that insects do not visit flowers because the flowers are 

 beautiful or fragrant, but because they want food, the color and 

 fragrance standing merely as the indication of the presence of food. 

 The food, however, is so placed that the insect securing it bears away 

 upon its body greater or less quantities of pollen. As it visits another 

 flower of the same kind, this pollen is brushed off by the stigma, and 

 pollination results. The devices for insuring that the pollen be thus 



