viii. PREFACE. 



If the style in which I have written be some- 

 what varied, it must be borne in mind that the 

 conditions under which the writing has been done 

 have also been varied, and this must be my apology 

 for any deficiency which may be found in its pages. 

 Most of the chapters have been written off without 

 the opportunity of reference to other books. Several 

 of them have been penned whilst crossing the 

 Atlantic, some in railway station waiting-rooms, 

 often during a midnight wait, or in the early hours 

 of the morning. A part was written at sea in the 

 cabin of a trawler, and the rest has been put. 

 together amidst the scenes of a very busy life. For 

 my knowledge of the subject I am indebted largely to 

 my own perseverance, and determination to under- 

 stand thoroughly that which I had taken up as my 

 life's work ; as well as to many fellow-labourers in 

 the same field, who have given me the benefit of 

 their knowledge. 



It is interesting to look back upon the work of 

 thirty years that have passed away, and to note how 

 one has been led, and how the work has developed, 

 at times under considerable difficulties, until it has 

 reached its present magnitude. The present seems 

 a fitting opportunity for tendering my warmest 

 thanks to some of those who have aided me in my 

 investigations of so fascinating a subject. To the 

 late Frank Buckland I am indebted for my first 



