STATE OF ILLINOIS 
DEPARTMENT OF REGISTRATION AND EDUCATION 
DIVISION OF THE 
NATURAL HISTORY SURVEY 
STEPHEN A. FORBES, Chief 
Vol. XIIL. BULLETIN Article II. 
WAYS AND MEANS OF MEASURING THE 
DANGERS OF POLLUTION TO 
FISHERIES 
BY 
VICTOR E. SHELFORD 
SSS 
AN 
TATE SY 
3 OF 
PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS 
URBANA, ILLINOIS 
September, 1918 
