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THE POPULAR SCIENCE MONTHLY, 



nation, can set no seed. For many trees, and for grasses generally, 

 the office of transporting the pollen is performed by the wind. And, 

 " as the wind bloweth where it listeth," it may waste a million pollen- 

 grains for every one it lodges on a stigma. Hence the prodigality of 

 pollen. If you walk through a field of corn, you will note how gener- 

 ously the tassel yields its pollen to the wind. If, toward the last of 

 May, you shake a branch of pine, you will see floating from it a cloud 

 of pollen-grains. 



Having seen the largest prodigality, we will search now for the 

 closest economy. 



In many of the violets we find, in addition to the showy flowers, 

 another set borne on runners and concealed under leaves. In the 

 fringed polygala we have another case of dimorphism. In one flower 

 the petals are of richest pink, two of them spreading out like wings, 

 and the other, keel-shaped, crested and fringed. Another flower, which 

 never opens, is borne close to the ground, or even in the ground, on 

 subterranean shoots. Now, these ground flowers of the violet and 

 polygala are self-fertilizing. One grain of pollen is enough for one 

 seed, and that is all which Nature, in these flowers, will furnish. 



You will observe now that the pine and the corn, in general all 

 conifers and grasses depending for fertilization on the wind, have col- 

 orless flowers and much pollen, and that concealed flowers are with- 

 out color and have but little pollen. We begin to suspect that color 

 stands in some relation to the needs of the flower. In the grasses and 

 pines it would be of no use, as the wind will find a dull flower as easily 

 as a gaudy one. In self-fertilizing flowers it is also of no use. 



Fig. 1. 



Eighty years ago Sprengel maintained that breeding in and in 

 would be as injurious in the vegetal as in the animal world, and he 

 argued that colors and odors attract insects and thus secure cross-fer- 

 tilization. It was the largest thought which had ever entered the head 

 of a botanist. But Sprengel was ridiculed in his own generation and 



