AMERICAN SCIENCE SERIESADVANCED COURSE 



THE HUMAN BODY 



AN ACCOUNT OF 



ITS STRUCTURE AND ACTIVITIES AND THE 

 CONDITIONS OF ITS HEALTHY WORKING 



H. NEWELL MARTIN, D.Sc., M.A., M.D., F.R.S. 



Late Professor of Biology in the Johns Hopkins University 



and of Physiology in the Medical Faculty 



of the same 



NINTH EDITION, THOROUGHLY REVISED 



BY 



ERNEST G. MARTIN, PH.D. 



Assistant Professor of Physiology in the Harvard Medical School 



j 



NEW YORK 

 HENRY HOLT AND COMPANY 



1912 

 ^ 



