The University of Chicago Science Series 



HTHE purpose of this important new series is 

 -'- to enable the investigator to present the re- 

 sults of his special researches, not only to a wider 

 public but to his scientific colleagues, in a more 

 attractive and accessible form than that of scat- 

 tered contributions in technical journals. 



The First Published Volume of the Series 



The Evolution of Sex in Plants. By John 

 Merle Coulter, Head of the Department 

 of Botany, viii-l-140 pages, small i2mo, 

 cloth; $1.00, postage extra (weight 14 oz.). 



Volumes in Preparation for Early 



Publication 



The Origin of the Earth. By Thomas C. Cham- 

 BERLIN, Head of the Department of Geology. 



The Isolation and Measurement of the Electron. 



By Robert Andrews Millikan, Professor of 

 Physics. 



Finite CoUineation Groups. By Hans F. Blich- 

 FELDT, Professor of Mathematics in Leland 

 Stanford Junior University. 



Individuality in Organisms. By Charles Manning 

 Child, Associate Professor of Zoology. 



Chemical Signs of Life. By Shiro Tashiro, In- 

 structor in Physiological Chemistry. 



THE UNIVERSITY OF CHICAGO PRESS 



CHICAGO ILLINOS 



Corrosion-Resisting 



Put a piece of metal in acid, and 

 see the tiny bubbles stream up- 

 ward. That's corrosion you can see. 

 Dip an ordinary pen in ink (Ink contains acid) 

 and the same thing takes place, only so gradu- 

 ally that you can't see it. 

 The corrosion -resisting metal of all Esterbrook 

 Pens is the result of 50 years 'exhaustive metal- 

 lurgical and chemical research. 

 Esterbrook Pens last 



If you like a smooth, easy-writing pen that 

 makes a fine quick-drying line, try this Elster- 

 brook Inflexible No. 322. 



Cpn J I A« For useful metal box containing 

 OUliU I \j\J this and eleven other most popular 

 pens, including- the famous 048 Falcon. 



ESTERBROOK PEN MFG. CO. 

 24-70 Cooper Street, Camden, N.J. 



EsterbrooK ^_ 



Inflesiblo N6, 322 W. 







Circular of larger sizes upon request 



DONTJUDGE BY THE PRICE 



The high prices charged for the majority of office appliances 

 may lead some people to doubt the value of the 



DAUS' IMPROVED TIP TOP DUPLICATOR 



on account of its low price ($5-00), but the fact that it is used and 

 endorsed by the N.Y. Central Railroad, U. S. Steel Corporatinn, Westlnshouse 

 Electric Co., etc., proves that the work done must be first-class. 

 High-class endorsements are strong arguments, but we do not 

 depend upon them to sell our Daus' Tip Top, preferring to have 

 you try it yourself before buying, by taking advantage of our offer of 

 10 Days' Trial without Deposit 

 Each machine contains a continuous roll of our new "Dausco" 

 Oiled Parchment Back duplicating surface which may be used over and 

 over again. Five different colors can be duplicated at once. No 

 ' printer's ink or expensive supplies required. lOo copies from pen- 

 written and so copies from typewritten original. 

 Complete Duplicator, cap size (prints iyi X 13 inches.) Price, d» C f\f\ 

 $7.50, less special discount of 33 J^ per cent, net «P**»W 



FELIX E. DAUS DUPLICATOR CO. Daus Building, 111 John Street, New York 



THE UNIVERSITY OF CHICAGO PRESS 



Has issued nearly seven hundred books on subjects in philosophy, psychology, 

 education, Greek, Latin, comparative philology, classical archaeology, Semitic, 

 Germanic, English, Romance languages, Slavic^ political economy, political science, 

 sociology, anthropology, history, religion and theology, botany, physiology, zoology, 

 anatomy, pathology, physics, chemistry, geology, geography, astronomy, astro- 

 physics, mathematics, and bibliography. A complete catalogue will he sent on 

 application. Address 



THE UNIVERSITY OF CHICAGO PRESS, CHICAGO. ILLINOIS 



