BULLETIN 



OF THE 



ILLINOIS STATE LABORATORY 



OF 



NATURAL HISTORY 



Urbana. Illinois. U.S.A. 



Vol. VI. NOVEMBER, 1903 Article II. 



THE PLANKTON OF THE ILLINOIS RIVER, 1894-1899, WITH IN- 

 TRODUCTORY NOTES UPON THE HYDROGRAPHY OF THE ILLINOIS 

 RIVER AND ITS BASIN. PART I. QUANTITATIVE INVESTIGATIONS AND 

 GENERAL RESULTS. 



BY 



C A. KOFOID, PH.D. 



