THE FLOWERING PLANTS. 25 



fertilization, i.e., fertilization of the ovary by pollen pro- 

 duced in an anther on the same flower, is the exception. 

 Cross fertilization, or fertilization by pollen borne on some 

 other plant of the same or a closely related species, is 

 the rule. Self fertilization tends to deterioration ; cross 

 fertilization tends to produce stronger and healthier plants. 

 To effect cross fertilization the pollen is carried by the 

 wind, by insects, and in some cases by birds. As a rule 

 plants that do not bear colored flowers are fertilized 

 by the wind, or are anemophilous ; those that bear col- 

 ored or conspicuous flowers are entomophilous, i.e., are 

 fertilized by insects or birds. The colors, fragrance, and 

 honey in flowers are contrivances of nature to attract 

 insects, which carry the pollen from one flower to another 

 as they search for their food. Not only do we owe the 

 beautiful colors and sweet odors of flowers to this neces- 

 sity of receiving pollen from other plants, but nature has 

 caused the parts of flowers to assume a great variety of 

 curious and interesting shapes to adapt them to receive 

 visits from insects that can benefit them by depositing 

 the pollen in the right place, and to shut out other insects 

 that might rob them of their honey without rendering 

 them service in turn. It is interesting to notice, also, 

 that parallel with these modifications in the shapes of the 

 flowers, there have resulted corresponding modifications 

 in the structure of insects. Certain insects and certain 

 flowers may almost be said to exist for mutual benefit. 

 This subject opens most extensive fields for intensely 

 interesting study. The present limits allow mere men- 

 tion to be made of it. In the season of the flowers 

 take every opportunity to watch insects visiting flowers. 

 Write out an account of what you observe. 1 



1 See Darwin's "Self and Cross Fertilization of Flowers" ; Sir John 

 Lubbock's "Flowers, Fruits, and Leaves"; and Weed's "Ten New 

 England Blossoms and Their Insect Visitors." 



