i 



THE SYSTEM OF 

 ANIMATE NATURE 



THE GIFFORD LECTURES DELIVERED IN 



THE UNIVERSITY OF ST. ANDREWS 



IN THE YEARS 1915 AND 1916 



i BY 



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



Professor of Natural History in the University of Aberdeen 



IN TWO VOLUMES 

 Vol. I 



NEW YORK 



HENRY HOLT AND COMPANY 



1920 



