VIU AUTHOR S PREFACE 



necessarily matters of controversy, an attempt has been made to 

 state the views of experts as objectively as possible, without attempt- 

 ing to assess the merits of rival theories. As far as possible the 

 material has been arranged uniformly in each chapter, under the 

 headings of introduction, organization, and results. Territorial 

 arrangement has been followed when subjects lent themselves to 

 such treatment. 



Unfortunately shortage of time has resulted in the omission of 

 much interesting work, particularly in the Union of South Africa 

 and in the French territories, and there is consequently a lack of 

 proportion in the treatment of some subjects. Much as I regret 

 this, it seemed preferable to a general scaling down of the volume 

 in order to preserve a more even balance. 



In addition to those mentioned in the list, I would like to thank 

 Lord Hailey and the members of the African Research Survey 

 Committee, as well as Miss Hilda Matheson, for help and advice 

 in all stages of the work; Professor J. Stanley Gardiner for reducing 

 my duties in the Zoological Department at Cambridge to a 

 minimum, so that I have been enabled to spend as much time as 

 possible on this work; the Conference of East African Governors, 

 for providing me with a research assistant, so that studies of 

 African lakes have been continued at the same time; my wife, for 

 much assistance in extracting information and translating foreign 

 memoranda; Miss J. L. Hopkins, for performing many duties 

 which usually fall outside the scope of secretarial assistance, and 

 Mrs. R. M. C. Fasnacht for preparing the index. When preparing 

 the final draft for press Dr. L. Mair and Dr. M. Lambert very 

 kindly revised the whole volume from an editorial viewpoint, and 

 most of the chapters were submitted to individual experts for final 

 comment and revision, in some cases involving considerable addi- 

 tions and corrections. These experts, to whom thanks are specially 

 due, were as follows (the numbers in brackets indicating the chap- 

 ters examined): Sir A. Richard Gregory, Bt., F.R.S. (I), Brigadier 

 M. N. MacLeod, D.S.O., M.C. (H), Professor O. T.Jones, F.R.S. 

 (HI), Mr. L. W. C. Bonacina (IV), Sir E.John Russell, F.R.S. 

 (V and XI), Dr. G. V.Jacks (V), Mr. A. D. Cotton, O.B.E. (VI), 

 Mr. J. N. Oliphant, Professor R. S. Troup, C.M.G., CLE., 

 F.R.S., and Dr. J. Burtt Davy, F.R.S. (VII), Dr. Julian S. 



