XX PREFACE 



As to the physicochemical actions and reactions of the 

 hving organism I have drawn especially from Loeb's Dynamics 

 of Living Matter. In the physicochemical section I am also 

 greatly indebted to the very suggestive work of Henderson 

 entitled The Fitness of the Environment, from which I have 

 especially derived the notion that fitness long antedates the 

 origin of life. Professor Hans Zinsser, of Columbia University, 

 has aided in a review of Ehrlich's theory of antibodies and the 

 results of later research concerning them. Professor Ulric 

 Dahlgren, of Princeton University, has aided the preparation of 

 this work with valuable notes and suggestions on the light, 

 heat, and chemical rays of the sun, and on phosphorescence 

 and electric phenomena in the higher organisms. 



In the geochemical and geophysical section I am indebted 

 to my colleagues in the National Academy, F. W. Clarke and 

 George F. Becker, not only for the revision of parts of the 

 text, but for many valuable suggestions and criticisms. 



For suggestions as to the chemical conditions which may 

 have prevailed in the earth during the earliest period in the 

 origin of life, as well as for criticisms and careful revision of 

 the chemical text I am especially indebted to my colleague in 

 Columbia University, Professor William J, Gies. 



In the astronomic section I desire to express my indebted- 

 ness to George Ellery Hale, of the Mount Wilson Observatory, 

 for the use of photographs, and to Henry Norris Russell, of 

 Princeton University, for notes upon the heat of the primordial 

 earth's surface. In the early narrative of the earth's history 

 and in the subsequent geographic and physiographic charts 

 and maps Professor Charles Schuchert and Professor Joseph 

 Barrell, of Yale University, kindly cooperated with the loan of 

 illustrations and otherwise. In the section on the evolution of 

 bacteria, which is a part pertaining to the idea of the early 



