x PROBLEMS OF RELATIVE GROWTH 



S. F. Bush, Professor F. W. Kunkel, Mr. J. A. Robertson, 

 Miss I. Dean, Mr. A. S. Edwards and Mr. F. S. Callow, without 

 whose collaboration I should never have been able to collect 

 and analyse the data on which this treatment of the subject 

 is founded. Finally, I must not forget my secretary, Miss 

 P. Coombs, whose aid has been invaluable in preparing the 

 book for the press. 



Many of the figures have been drawn for this book. As 

 regards the others, I would like to express my thanks for the 

 willingness of the authors and publishers concerned for allow- 

 ing me to reproduce them. Acknowledgements have been 

 made in the list of illustrations : the citations there made 

 refer to the literature list for fuller details. 



JULIAN S. HUXLEY 

 King's College, London 

 December, 1931 



