PRACTICAL POLLINATION 259 



It differs from the bud from which it is de- 

 veloped chiefly in that it requires to be fertilized 

 by union with a pollen cell, before it is capable of 

 taking on development; and in the further very 

 essential fact that when mature it may be cast off 

 from its original moorings and carried to any 

 distance, thus in a way making amends for the 

 limitations put upon vegetables by their inca- 

 pacity for locomotion. 



The stamens that normally grow in a circle 

 about the central pistil develop at their ends 

 anthers that produce, usually in relatively large 

 quantities, pollen grains of exceedingly minute 

 size. And each pollen grain contains, somewhat 

 as does each ovule, all the hereditary potentiali- 

 ties of the entire plant. The pollen grain cannot, 

 indeed, be made to develop into a plant; but its 

 union with the ovule is essential to the develop- 

 ment of that organism, and it is certain that the 

 pollen grain, despite its infinitesimal size, brings 

 to the union factors that represent its parent 

 plant effectively and in full measure. 



It would be unbelievable, if we did not know 

 it to be true, that a fleck of matter of scarcely 

 more than microscopic size should contain the 

 potentialities of a mammoth tree, and should 

 predetermine the details of structure of a future 

 tree even to its remotest leaf and to the finest 



