BULLETIN 
OF THE 
ILLINOIS STATE LABORATORY 
OF 
NATURAL HISTORY 
UEPann Tmo: i--Sy A: 
Wore itt: ARTICLE I, 
THE PLANKTON OF THE ILLINOIS RIVER, 1894-1899, WITH 
INTRODUCTORY NOTES UPON THE HYDROGRAPHY 
OF THE ILLINOIS 
RIVER AND ITS BASIN. 
PART II. CONSTITUENT ORGANISMS AND 
THEIR SEASONAL DISTRIBUTION. 
= 
o 
BY 
Cy x. KOFOLD) Pr, 
