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HUMAN PHYSIOLOGY 



A Text-Book for High Schools and Colleges 



BY 

 PERCY GOLDTHWAIT STILES 



ASSISTANT PROFESSOR OF PHYSIOLOGY IN HARVARD UNIVERSITY; 



FORMERLY ASSISTANT PROFESSOR OF PHYSIOLOGY IN SIMMONS 



COLLEGE, BOSTON; INSTRUCTOR IN THE BOSTON SCHOOL OF 



PHYSICAL EDUCATION 



SECOND EDITION, REVISED 



PHILADELPHIA AND LONDON 



W. B. SAUNDERS COMPANY 



1919 



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