516 



seine of one-inch mesh. The nets fished weH, as a rule, as far as 

 seventy-five feet from shore, in the fuU current with water four to 

 nine feet deep, but no Hving fish were taken by any of these hauls. 

 Two dead shiners were in the net February i8, and a small specimen 

 of the same species, in a dying condition, was picked up by hand 

 near the shore February 24. It had perhaps been washed in from 

 Au Sable Creek. A hoop-net, with a 6-foot opening, and two smaller 

 fykes with 2-foot and 3-foot openings were kept continuously fishing 

 from February 20 to March 2, alternating between the north and 

 the south shores, but not a fish was taken by them at any time. 

 Twenty- four sticks of dynamite were exploded on both sides of the 

 river and in the midstream, but the only fish to appear was a single 

 shiner, near the south shore, a hundred yards above the mouth of 

 Mazon slough. February 28, a neighboring farmer found a 15- 

 pound carp on the ice near the north shore below Au Sable Creek. 

 The fish was probably sick or suffocated, and trying to get air. On 

 the 2d of March, several perch and shiners, and a single carp eight 

 or ten inches long, were taken in cleaning out the pump-house tank 

 of the Rock Island Railroad, the intake of which is seventy-five feet 

 from the north shore of the stream. As the tank had last been 

 cleaned February i, these fish must have been pumped in since that 

 date. The stomachs and intestines of all the specimens taken at 

 Morris between February 16 and March 2 were quite empty. 



Summer and Fall of ipi2. — In August and September, 1912, 

 Morris was twice visited for systematic collections of fish and of the 

 shore and bottom forms of animals and plants — the first time August 

 I to 10, and the second, September 23 to October i. The river level 

 stood, in the beginning, at twenty inches above the July stage of 

 191 1, fell slowly to eight inches above by September 22, and then 

 rose to eleven inches by the end of the month. Specks of suspended 

 matter, largely Splicer otilus and Carchesium, gave the water a gray- 

 ish hue, and its smell was the same as in the summer of 191 1, but 

 less offensive. There was also less bubbling of gases from the bot- 

 tom, but the odor of the sludge was not noticeably different. 



Chemical determinations were made during this period only on 

 the 27th of September, at which time, with a water temperature 

 of 62.7° F., the oxygen reading for both the north shore and the 

 main stream was 17.9 per cent, of saturation (1.8 parts per million), 

 and that for the south side was 37.4 per cent. (3.7 parts per million). 



Persistent fishing was done with dip-nets, seines of various sizes, 

 set-nets, trammel-net, dynamite, dredges, and the mussel-bar, — the 

 last for Unios. Seven fishes were taken at this point in all — five of 



