PREFACE 



THIS book owes its origin to a series of eight lectures delivered 

 upon the invitation of Professor E. B. Wilson and Professor H. F. 

 Osborn at Columbia University in the spring of 1902. The aim of 

 the lectures was to give a presentation of my researches on the 

 dynamics of living matter and the views to which they had led me. 

 In preparing the book I have tried to give a somewhat more com- 

 plete survey of the field of experimental biology than was possible 

 in the lectures, without, however, trying to alter their character. In 

 the introductory lecture use was made of my address at the Inter- 

 national Congress at St. Louis. 



To Dr. S. S. Maxwell, who has undertaken the main burden of 

 reading the proof and preparing the index, and to Professor J. B. 

 MacCallum, who also assisted me in the reading of the proof, my 

 sincere thanks are due. 



BERKELEY, CALIFORNIA, 

 January I, 1906. 



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