FERTILIZATION IN THE VEGETABLE KINGDOM. 233 



on a large tree, if other and adjoining flowers were cross- 

 fertilized. Of the flowers annually produced by a great 

 tree, it is almost certain that a large number would be self- 

 fertilized ; and if we assume that the tree produced only 

 500 flowers, and that this number of seeds were requisite to 

 keep up the stock, so that at least one seedling should here- 

 after struggle to maturity, then a large proportion of the 

 seedlings would necessarily be derived from self-fertilized 

 seeds. But if the tree annually produced 50,000 flowers, of 

 which the self-fertilized dropped off without yielding seeds, 

 then the cross-fertilized flowers might yield seeds in sufficient 

 number to keep up the stock, and most of the seedlings would 

 be vigorous from being the product of a cross between dis- 

 tinct individuals. In this manner the production of a vast 

 number of flowers, besides serving to entice numerous insects 

 and to compensate for the accidental destruction of many 

 flowers by spring-frosts or otherwise, v/ould be a very great 

 advantage to the species ; and when we behold our orchard- 

 trees covered with a white sheet of bloom in the spring, 

 we should not falsely accuse Nature of wasteful expendi- 

 ture, though comparatively little fruit is produced in the 

 autumn." 



The Horse-Chestnut is not altogether a well-chosen ex- 

 ample, for in it, as in our Buckeyes, a very large projwrtion 

 of the flowers in the thyrsus are usually male, with barely a 

 vestige of pistil. These serve, however, to increase the show, 

 in the manner here illustrated, as well as to furnish abun- 

 dance of pollen. 



The section on anemophilous (wind-fertilized) plants, — 

 their interest as survivals of the earlier phtenogamic vegetatiou, 

 the speculation as to how, when flying insects came to prevail, 

 an anemophilous plant may have been rendered entomophi- 

 lous, — how pollen, being a most nutritious substance, would 

 soon have been discovered and devoured by insects, and by 

 adhering to their bodies be carried from anthers to stigma 

 and from one flower to another, — how a waste secretion, such 

 as honey-dew or glandular exudations, may have been devel- 

 oped into nectar and utilized as a lure, — the interesting illus- 



