XX ACKNOWLEDGEMENTS 



of Experimental Biology, Biological Reviews, Science Progress, and the Monist, 

 for permission to reprint passages from papers. I must record my gratitude 

 to the following friends, who very kindly read through and criticised the 

 proofs of the various sections: 



Part I 



Professor A. E. Boycott 

 Dr J. H. Woodger 



Part II 



Professor R. C. Punnett 

 Dr Charles Singer 

 Dr Reuben Levy 

 Dr Arthur Peck 

 Sir William Dampier 

 Professor A. B. Cook 

 The Rev. W. Elmslie 

 Professor F. M. Cornford 



Part III 



Section 



1 Professor R. H. A. Plimmer 

 Mr J. B. S. Haldane 



2 Dr Samuel Brody 

 Mr James Gray 

 Dr E. N. Willmer 



3 Mr G. R. de Beer 



Mr C. H. Waddington 

 Mr J. B. S. Haldane 



4 Dr D. Keilin 

 Professor Munro Fox 



5 Mr T. R. Parsons 

 Dr Malcolm Dixon 



6 M. Louis Rapkine 

 Mr C. Forster Cooper 



7 Miss Marjory Stephenson 

 M. Louis Rapkine 



Dr D. Keilin 



8 Dr Eric Holmes 



Dr Bruce Anderson & Mrs Margaret 

 Whetham Anderson 



