To the young physicians and biologists, 



Fellows of various foundations and scientific societies, 



who came from other lands 



to study with the author of this book 



problems common to all humanity 



Sidney Arthur Asdell, Cambridge, England 



Seitchi Saiki, Tokyo, Japan 



Eduardo Burster Montero, Santiago, Chile 



Friedrich Hoffmann, Dusseldorf, Germany 



Graham Weddell, London, England 



Ines Lopez Colombo de Allende, Cordoba, Argentina 



Luis Vargas Fernandez, Santiago, Chile 



Washington Buno, Montevideo, Uruguay 



WE TOOK counsel TOGETHER 



AND WALKED IN THE WAY OF TRUTH 



AS FRIENDS 



Published by Atheneum 

 Reprinted by arrangement with Princeton University Press 



Copyright 1942, 1947 by Princeton University Press 



All rights reserved 



Manufactured in the United States of America by 



The Murray Printing Company, Forge Village, Massachusetts 



Bound by The Colonial Press, Clinton, Massachusetts 



Published in Canada by McClelland & Stewart Ltd. 



First Atheneum Edition 



