vi PREFACE 



Dr Anderson*. At a later stage I learned much from Dr Gaskell, 

 Professor Langley and Dr Haldane. 



There are occasions on which every sailor of the deep sea has to 

 ship a pilot. Mr A. V. Hill has brought me into those harbours 

 which are best approached through the, to me, unknown channels of 

 mathematics. 



♦ Formerly supervisor in physiology to King's College, now Master of Gonville 

 and Caius College. 



J.B. 



Cambridge, 

 December, 1913. 



