vi AUTHOR'S PREFACE. 



in the discovery of their own similarities to forms of life 

 unlike themselves, and in the fact that life powers are not 

 theirs by right to the exclusion of other animals, which 

 may even transcend them in some of these powers. 



The writer stands indebted to several authors whose 

 work has covered a much larger field, notably Comstock, 

 Folsom, Galloway, and Kellogg, and the many excellent 

 workers in the Government Biological Survey and the 

 Bureau of Entomology. Courteous permission was given 

 to use various illustrations, by Henry Holt & Co., by 

 Doubleday, Page & Co., of New York, and by James T. 

 Hathaway, of New Haven, Conn. 



