A TEXT-BOOK 



OP 



PHYSIOLOGY 



FOR 



MEDICAL STUDENTS AND PHYSICIANS 



BY 



WILLIAM H. HOWELL. Ph. D., M. D., Sc. D.. LL.D. 



PROFESSOR OF PHYSIOLOGY IN THE JOHNS HOPKINS UNIVERSITY, BALTIMORE 



Bigbtb EDition, ^TbocougblB iRevlseO 



PHILADELPHIA AND LONDON 



W. B. SAUNDERS COMPANY 



1022 



