375 
Copperas Creek and Havana, we get a yield of 1,447 pounds per acre, to 
be compared with 705 pounds per acre for the unusually rich sections of 
the river opposite. 
From analyses of the bottom muds of the river channel and esti- 
mates of the nitrogen content of total bottom fauna per acre, it appears 
that the nitrogen in the river sediments is many hundred times the nitro- 
gen content of the flesh of the animals living in them, and that the total 
dry organic matter in the channel muds is several thousand times the 
dry weight of this bottom fauna. 
Chemical analyses show that the bottom soils of the lakes are richer 
in organic matter than those of the river opposite them, and that in the 
lakes themselves the bottom soil is richer near the shore than at the center. 
The plankton of the river passing Havana in a year amounts to about 
200,000 tons live weight, equivalent to four thousand to ten thousand 
tons dry weight. This is, roughly, 20 to 50 times the total dry weight of 
the flesh of the animals of the bottom muds of the lakes from Copperas 
Creek to the mouth, a distance of 138 miles. 
An estimated total of 600,000 tons dry weight of organic matter, 
suspended and dissolved, passed Chillicothe in 1914. This is 60 to 150 
times the dry weight of the plankton that passed Havana in twelve 
months (1909 and 710), and 3,000 times the dry weight of the total bot- 
tom fauna of 1915 from Copperas Creek to the mouth of the river. 
The dry weight of nitrogen in the above organic matter was sufficient to 
replace the nitrogen in the plankton of a year from 92 to 232 times. 
The plankton per cubic meter of water was greater throughout the 
year in Thompson Lake than in the river opposite in 1909 and ’10, the 
difference being greatest at times of lowest production (midsummer and 
winter) in both river and lake. 
The river plankton is constantly settling to the bottom to an impor- 
tant degree, as is shown by the composition of the bottom ooze and by 
the stomach contents of small invertebrates living on and in it. In June, 
1914, living, moribund, or recently dead limnetic plankton was more 
abundant in the upper layers of the ooze than the normal bottom plank- 
ton or old organic detritus, as was shown by the food of Sphaeriidae, 
Trichoptera, and Chironomidae, and it made also an important part of 
the food of large detritus-eating gastropods (Viviparidae, Pleuroceridae, 
etc.). 
There is a much greater loss of plankton down-stream than can be 
explained by dilution merely. The falling off in plankton per cubic 
meter between Havana and Grafton amounted, during nine months of 
the growing season, to approximately 62 per cent., notwithstanding the 
normal rate of multiplication of the planktonts as they. passed down 
stream. These losses were greatest when the current was slowest and 
settling consequently easiest. They were not due to lack of food, because 
the percentage of nitrogen and the nitrates increased from Havana down- 
ward. 
