[p.i] THE UNIVERSITY OF CHICAGOSCIENCE SERIES
Editorial Committee
ELIAKIM HASTINGS MOORE, Chairman
JOHN MERLE COULTER
ROBERT ANDREWS MILLIKAN
[p.ii] The University of Chicago Science Series, established by theTrustees of the University, owes its origin to a feeling that thereshould be a medium of publication occupying a position between thetechnical journals with their short articles and the elaborate treatiseswhich attempt to cover several or all aspects of a wide field. Thevolumes of the series will differ from the discussions generallyappearing in technical journals in that they will present the completeresults of an experiment or series of investigations which previouslyhave appeared only in scattered articles, if published at all. On theother hand, they will differ from detailed treatises by confiningthemselves to specific problems of current interest, and in presentingthe subject in as summary a manner and with as little technical detailas is consistent with sound method.
[p.iv] THE UNIVERSITY OF CHICAGO PRESSCHICAGO, ILLINOIS
Agents
THE BAKER & TAYLOR COMPANY
NEW YORK
THE CUNNINGHAM, CURTISS & WELCH COMPANY
LOS ANGELES
THE CAMBRIDGE UNIVERSITY PRESS
LONDON AND EDINBURGH
THE MARUZEN-KABUSHIKI-KAISHA
TOKYO, OSAKA, KYOTO, FUKUOSA, SENDAI
THE MISSION BOOK COMPANY
SHANGHAI
By
EDWIN OAKES JORDAN
Chairman of the Department of Hygiene and Bacteriology
The University of Chicago
THE UNIVERSITY OF CHICAGO PRESS
CHICAGO, ILLINOIS
[p.vi] Copyright 1917 By
The University of Chicago
All Rights Reserved
Published May 1917
Composed and Printed By
The University of Chicago Press
Chicago, Illinois, U.S.A.