THE SYSTEM OF 

 ANIMATE NATURE 



THE GIFFORD LECTURES DELIVERED IN 



THE UNIVERSITY OF ST. ANDREWS 



IN THE YEARS 1915 AND 1916 



BY 



J. ARTHUR THOMSON, M.A., LL.D. 



Professor of Natural History in the University of Aberdeen 



IN TWO VOLUMES 

 VOL. I 



LONDON 



WILLIAMS & NORGATE 



1920 



