508 



held together by threads of algae and fungi and growths of branching 

 colonial bell-animalcules, rose from the bottom buoyed up by the 

 gases developed within them, but settled quickly when they were 

 broken apart by a light touch. Noticeably cleaner water, with a less 

 offensive smell, carrying also much less Sphccrotihis and Carchesium, 

 was found along the south shore, where the Kankakee contribution 

 still had a discernible influence. The water temperatures of the 

 surface layer were 69.1° F. July 28, 73° August 11, and 73° August 

 23. 



October 11, when the water was three feet higher than in August, 

 conditions were greatly improved, the water being much less offen- 

 sive in odor, with no bubbling of gases and no floating masses of 

 detached sludge. The feathery tufts of Sphccrotihis and Carchesium 

 were also much less abundant. Virtually the same statement may be 

 made for November 3, when the river level was about two feet above 

 that of the midsummer season, and for November 13, when it was 

 two or three feet higher still. 



Imperfect Mixture of Waters. — A study of conditions at Morris 

 was made difficult by the fact that the waters of various origin flow- 

 ing past that point were not yet thoroughly mingled, those of the 

 Kankakee predominating along the south bank and those of the Des 

 Plaines River and the sanitary canal along the north bank, while 

 the midstream current was made up of a variable mixture of the 

 two. This was most plainly shown by a comparison of the chemical 

 reports of the oxygen content of the water, on the same days but on 

 opposite sides of the stream. Determinations of oxygen, available 

 for this comparison, are as follows, stated in percentages of satura- 

 tion. 



The differences between the two sides of the stream varied with 

 the weather and with the stage of water, being greater in hot weather 

 than in cold, and greater also in high water than in low. In the 

 former case the more rapid decomposition of the organic matter 

 appropriated the oxygen more completely by the time the water of 

 the northern side of the river had reached Morris. The degrees of 



