451 
2. Stocks oF ToTAL NITROGEN AND NITRATES IN THE RIvER CHANNEL 
AT CHILLICOTHE, 1914—1915 
Comparison of the plankton figures obtained at Havana September, 
1909—August, 1910, with the total nitrogen and nitrate figures for 
Chillicothe, March, 1914—February, 1915, does not suggest that plank- 
ton production in the river between Havana and Peoria has been at all 
in danger of limitation by the nitrogen supply at any season during re- 
cent years. The total nitrogen that passed Chillicothe in the twelve 
months (67,722 tons) was sufficient, if all metabolized without loss, to 
produte more than ninety times the actual stocks of plankton that 
passed Havana in the year 1909—1910 (based on a dry-matter per cent. 
= 5; nitrogen per cent. in dry matter = 7) ; while the stock of unused 
nitrogen in the form of nitrates (22,345 tons) was capable of producing 
under the same conditions more than twenty times the total plankton 
that actually passed Havana in 1909—1910. At the dry matter and ni- 
trogen ratios assumed, only about 1,431,983 pounds out of the total 
of 35,444,859 pounds of nitrogen that passed Chillicothe in the year 
1914—1915 would be accounted for as nitrogen in the form of living 
matter in 400,000,000 pounds of plankton (the approximate amount that 
passed Havana September, 1909—August, 1910). 
If we could distribute the total nitrogen that passed Chillicothe 
over a river acreage of 26,782 acres (the estimated acreage below Chilli- 
cothe at about 8 ft., Havana, the average gage of July—November, 1910 
—1914), we would have 2,442 pounds per acre in the March—June pe- 
riod ; 1,495 pounds per acre July—November ; 1,119 pounds per acre De- 
cember—February; and a total of 5,057 pounds per acre for the year. 
The nitrates, similarly distributed with correspondingly lesser poundages 
for the separate seasons, would amount to 1,668 pounds per acre for the 
twelve months on the same acreage. 
The Peoria discharge data entering into the various tables following 
are the rating-table figures of Jacob A. Harman, as published in the 
special Report of the Illinois State Board of Health on Sanitary In- 
vestigations of the Illinois River, 1901, and more recently used by Alvord 
and Burdick in the Report of the Rivers and Lakes Commission on the 
Illinois River and its Bottom-lands, 1915. These figures are consider- 
ably higher than recent figures of the U. S. Geological Survey, which we 
did not have at hand, except in fragmentary form, when the manu- 
script for the present article was being prepared. 
