506 ♦ 



men of the last species was found alive among algce in the drift. 

 Numerous Chironomus eggs were in the same situation; and air- 

 breathing beetles — Dincutcs and Gyrimis — were also common, but 

 there were no water-breathing larv?e except Cliirojwmus. Slime 

 worms (Tubificidcr) were rare in the soft black sludge at the bottom 

 and the edge of the stream — a great contrast with conditions at Mor- 

 ris to be reported later. Splncyotilus was again very abundant on 

 weeds and sticks, and on old stems of Carchcsium lachmanui. Blue- 

 green alg?e, chiefly Oscillatoria limosa and Phoniiidiiim imcinatum, 

 were fairly frequent. The green filamentous algcT, Stigeoclonium 

 tcnuc, and Spirogyra, chiefly S. vcrnata, were common in both 

 August and September, and Ulothrix zonata in the latter month; 

 and some Lemna and JVolffia were caught in the drift along the 

 bank. Protoj:oa were represented mainly by fixed forms, especially 

 by CarcJicsiiim, attached to sticks or floating in the water. There 

 were no sponges, hydroids, leeches, planarians, or crustaceans. 



The general impression to be gained from these midsummer and 

 autumn data is that of a heavily polluted stream with less oxygen 

 and more carbon dioxide than was consistent with the life of fishes, 

 mollusks, insect larv^, or crustaceans, and with the natural tauna 

 of the stream represented by saprobic organisms, except at its edges, 

 where oxygen enough was absorbed from the air to serve the needs 

 of a few green algse and an insignificant group of associated ani- 

 mals. Decomposition of its sewage materials had not yet reached 

 its climax, which came at Morris and Marseilles at low water in the 

 hottest weather, and at various distances farther down when the 

 water was higher or the weather cooler, — farthest, of course, when 

 these conditions were coincident. 



The Kankakee River at Dresden Heights 



Conditions in the Kankakee at its mouth are particularly inter- 

 esting and important since they give us a close approximation to 

 those of the natural water of the Illinois River, derived, as they are, 

 from a territory similar in character to the valley of the Illinois 

 below, and contaminated but slightly, if at all at this place, by way 

 of contributions from comparatively small towns at some distance 

 above. Collections were made from the Kankakee at a point near 

 the east bank and two hundred yards above the mouth of the stream. 

 The samples were taken in two or three feet of water by wading 

 out or by working from an improvised trestle forty feet in length. 

 The river at this point is broad and shallow, with a moderately swift 

 current, probably two to three and a half miles per hour, becoming 



