BULLETIN 
OF THE 
ILLINOIS STATE LABORATORY 
OF 
NATURAL HISTORY 
URBANA, ILLINOIS, U. S. A. 
ee NATL. MAY, 1908 ee: a 
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. 
BY 
C. A. KOFOID, Pu.D. 
