PEEFACE 



THIS work is not a text-book of theoretical biology ; it is a 

 systematic presentment of those biological topics which bear 

 upon the true philosophy of nature. The book is written 

 in a decidedly subjective manner, and it seems to me that 

 this is just what " Gifford Lectures ' ought to be. They 

 ought never to lose, or even try to lose, their decidedly 

 personal character. 



My appointment as Gifford Lecturer, the news of which 

 reached me in February 1906, came just at the right 

 moment in the progress of my theoretical studies. I had 

 always tried to improve my previous books by adding notes 

 or altering the arrangement ; I also had left a good deal 

 of things unpublished, and thus I often hoped that I might 

 have occasion to arrange for a new, improved, and enlarged 

 edition of those books. This work then is the realisation 

 of my hopes ; it is, in its way, a definitive statement of all 

 that I have to say about the Organic. 



The first volume of this work, containing the lectures 

 for 1907 though the division into "lectures" has not been 

 preserved consists of Parts I. and II. of Section A, " The 

 Chief Kesults of Analytical Biology." It gives in Part I. a 



