485 



State Fish Commission, beginning at Montezuma, on the lower Illi- 

 nois River, going thence to Grafton, at its mouth, from Grafton up 

 the Mississippi to Quincy, down that stream to St. Louis, from St. 

 Louis back to Grafton, and thence up the Illinois to Pekin. The 

 systematic plankton collections of this trip were the first ever made 

 on the Mississippi River. Additional collections were obtained in 

 1902, by the use of the station launch, from Pekin to Peoria Nar- 

 rows, and in August, 1903, from Wesley, below Peoria, to Henry, 

 thirty-three miles above. The next long trip was made June 8-17, 

 1910, again on the steamer "Illinois," from Keokuk, Iowa, to Quincy 

 and St. Louis, and thence up the Mississippi and the Illinois to La 

 Salle, with a return to Havana; and additional materials for a study 

 of the plankton were obtained by means of numerous collections in 

 Peoria Lake, July 19-22 of this year. The final trip of the series 

 was made with the "Illinois" July 25 to August 6, from Havana 

 down the Illinois and the Mississippi to Cairo, and thence up the 

 Ohio to Paducah, Ky., where we left the steamer, to rejoin it at 

 St. Louis for continuous collections up the ^lississippi and the Illi- 

 nois to La Salle, and back to Havana. 



In 191 1, chemical determinations and biological collections for 

 an analysis of seasonal conditions on the upper Illinois and in re- 

 lated waters, were begun July 18 and repeated at frequent intervals 

 until the 13th of December. Similar trips were made in February 

 and March, 1912, for a study of winter conditions; and in July, 

 19 1 2, an elaborate series of oxygen determinations was made for 

 the entire length of the river. August 21 to October 12, two such 

 series were obtained for the upper Illinois ; and in November two 

 more, for the whole stream, with comparative tests for the Missis- 

 sippi, below and above the mouth of the Illinois. The situations 

 thus brought more or less closely into comparison were the sanitary 

 canal at Lockport, the Des Plaines River at the same place and at 

 its mouth (Dresden Heights), the Kankakee just above its mouth, 

 and the Illinois River at Dresden Heights, Morris, Marseilles (both 

 above and below^ the dam which crosses the river there), Ottawa, 

 Starved Rock, Peru, Hennepin, and Chillicothe. The distances of 

 these points from the mouth of the Chicago River are approximately 

 as follows, in miles : Lockport, 35 ; Dresden Heights, 53 ; Morris, 

 62; Marseilles, 80; Ottawa, 86; Starved Rock, 95; Peru, 102; 

 Hennepin, 116; and Chillicothe, 145, ninety-two miles of this last- 

 mentioned distance being on the Illinois River itself. 



In 191 1, low-water midsummer conditions were shown by studies 

 pursued between July 15 and August 29, during which time three 



