VI 



Carl Voegtlin, M.D. 



PEOFESSOB OF PHARMACOLOGY AND CHIEF OF DIVISION OF PHABMACOLOGY, HYGIENIC 

 LABORATORY, U. S. PUBLIC HEALTH SERVICE, WASHINGTON, D. C. 



Ward J. MacNeal, Ph.D., M.D. 



PROFESSOR OF PATHOLOGY AND BACTERIOLOGY AND DIRECTOR OF THE LABORATORIES, NEW 

 YORK POST-GRADUATE MEDICAL SCHOOL AND HOSPITAL, NEW YORK. 



