ORGANIC CONTENT OF LAKE WATER 
197 
proteins contain 50 to 55 per cent of carbon, and an average amount of 53 per cent 
may be assigned to them. Thus, the organic carbon may be divided at once into 
two parts, one belonging to the nitrogenous substances and the other to nonnitro- 
genous compounds. The first part equals 53 per cent of the weight of the crude 
protein and the remainder goes to nonnitrogenous substances. If the ether extract 
has not been determined (and this is true for most of the residues here considered), 
the nonnitrogenous substance must be computed as carbohydrate. This method 
involves an overestimate of the total amount of organic matter, proportional to the 
quantity of fat that is present; in the present cases the excess is about 3 per cent. 
The carbohydrates contain only a negligible amount of sugars, as is the case also 
with the water plants and plankton. They may be computed as starch or cellulose, 
containing an average of about 45 per cent of carbon. The “crude fiber,” so far as it 
contributes to the dissolved matter, comes either from plankton or higher water 
plants, and this also would have about the same composition. 
If, then, the organic carbon is distributed to proteins on the basis that 53 per 
cent of these consists of carbon, and to nonnitrogenous organic substances on the 
basis of 45 per cent of carbon, the following table will result: 
Table 8. — Total organic matter, milligrams per liter 
[D.=depth. N.=nitrogenX6.25, or crude protein. Nonn.= nonnitrogenous matter computed as carbohydrate. Pkn.=piankton. 
Dis.=dissolved organic matter.] 
Date 
Plankton 
Dissolved 
Total organic 
Per cent 
D. 
N. 
Nonn. 
Total 
N. 
Nonn. 
Total 
N. 
Nonn. 
Total 
Pkn. 
Dis. 
LAKES 
Mendota 
Oct. 
18, 1922 
0 
0. 66 
0. 59 
1.25 
2. 74 
5. 67 
8.41 
3. 40 
6. 26 
9. 66 
12.9 
87.1 
Do 
Dec. 
5, 1922 
0 
.90 
.83 
1. 73 
3. 02 
14. 10 
17. 12 
3. 92 
14. 93 
18. 85 
9.2 
90.8 
Do 
Feb. 
28, 1923 
0 
.32 
.56 
.88 
3. 46 
9.95 
13.41 
3. 78 
10.51 
14. 29 
6.2 
93.8 
Do 
July 
24, 1923 
0 
.70 
2. 67 
3. 37 
2. 44 
13. 48 
15. 92 
3. 14 
16. 15 
19. 29 
17.5 
82.5 
Do 
Sept. 
21, 1923 
0 
.57 
1.49 
2. 06 
2. 32 
7.22 
9.54 
2.89 
8.71 
11.60 
17.8 
82.2 
Do 
Oct. 
24, 1923 
0 
.28 
1.54 
1.82 
1.81 
11. 10 
12.91 
2. 09 
12.64 
14. 73 
12.4 
87.6 
Do 
Apr. 
23, 1924 
0 
.50 
.45 
.95 
2. 10 
10. 61 
12.71 
2. 60 
11.06 
13. 66 
7.0 
93.0 
Do 
June 
18, 1924 
0 
.58 
.74 
1. 32 
1. 92 
10. 12 
12.04 
2. 50 
10.84 
13.34 
9.7 
90.3 
Do 
July 
21, 1922 
20 
.31 
.38 
.69 
1.96 
8.44 
10. 40 
2.27 
8. 82 
11.09 
6.3 
93.7 
Do 
Sept. 
26, 1922 
20 
.30 
.55 
.85 
1.90 
8. 17 
10. 07 
2.20 
8. 72 
10. 92 
8.7 
91.3 
Do 
Feb. 
28, 1923 
20 
.36 
.42 
.78 
3. 50 
9. 50 
13.00 
3. 86 
9. 92 
13.78 
5.7 
94.3 
Do 
July 
24, 1923 
20 
.36 
1.13 
1.49 
2. 52 
10. 01 
12. 53 
2. 88 
11.14 
14. 02 
7.8 
92.2 
Do 
Sept. 
21, 1923 
20 
.62 
1.66 
2.28 
2. 35 
9. 92 
12.27 
2. 97 
11.58 
14. 55 
15.7 
84.3 
Do 
June 
25, 1924 
20 
.28 
.56 
.84 
2.23 
12. 65 
14. 88 
2.51 
13. 21 
15. 72 
6.0 
94.0 
Mean 
.48 
.97 
1. 45 
,2.45 
10.07 
12.52 
2.93 
11.03 
13.96 
10.2 
89.8 
Bass 
Dec. 
20, 1923 
0 
.21 
.36 
.57 
2. 66 
17. 76 
20. 42 
2. 87 
18. 12 
20. 99 
2.7 
97.3 
Devils _ 
July 
11, 1923 
0 
.24 
. 18 
.42 
1.37 
5.08 
6. 45 
1.61 
5. 26 
6. 87 
6.1 
93.9 
Do 
Oct. 
27, 1923 
0 
.19 
.20 
.39 
1.89 
6. 70 
8. 59 
2.08 
6.90 
8.98 
4.3 
95.7 
Geneva 
July 
16, 1923 
0 
.32 
.93 
1.25 
2. 11 
7. 55 
9.66 
2. 43 
8.48 
10.91 
11.5 
88.5 
Green 
July 
18, 1923 
0 
.26 
.67 
.93 
1.94 
6. 48 
8. 42 
2. 20 
7. 15 
9. 35 
10.0 
90.0 
Do 
Oct. 
16, 1923 
0 
. 30 
.59 
.89 
1.85 
12.28 
14. 13 
2. 15 
12. 87 
15. 02 
5.9 
94. 1 
Kegonsa 
July 
20, 1923 
0 
8. 62 
10. 66 
19.28 
4. 56 
10. 90 
15. 46 
13. 18 
21. 56 
34. 74 
55.5 
44.5 
Madeline 
Dec. 
12, 1923 
0 
.60 
1.14 
1.74 
2.84 
8. 35 
11. 19 
3. 44 
9. 49 
12. 93 
14.6 
85.4 
Michigan 
Feb. 
28, 1924 
0 
. 14 
1.48 
1.62 
.89 
6. 15 
7.04 
1.03 
7.63 
8. 66 
18.7 
81.3 
Monona 
June 
28, 1923 
0 
2. 43 
2. 77 
5.20 
4. 45 
12. 34 
16. 79 
6.88 
15.11 
21.99 
23.7 
76.3 
Rock 
July 
6, 1923 
0 
.46 
.56 
1. 02 
3. 44 
14. 14 
17.58 
3. 90 
14. 70 
18. 60 
5.5 
94.5 
Turtle 
Jan. 
18, 1924 
0 
.19 
.55 
. 74 
3. 06 
25. 75 
28. 81 
3. 25 
26. 30 
29. 55 
2.5 
97.5 
Waubesa 
July 
20, 1923 
0 
3. 74 
4.41 
8. 15 
4. 65 
10. 32 
14. 97 
8. 39 
14. 73 
23. 12 
35.2 
64.8 
Wingra— - . 
June 
26, 1923 
0 
5. 51 
11. 70 
17. 21 
4. 51 
15.83 
20.34 
10.02 
27.53 
37. 55 
45.8 
54.2 
RIVERS 
Wisconsin 
July 
30, 1923 
0 
1. 01 
1. 56 
2. 57 
3.04 
30. 24 
33.28 
4. 05 
31.80 
35. 85 
7.2 
92.8 
Do 
Nov. 
21, 1923 
0 
.34 
.67 
1.01 
2.46 
18.98 
21.44 
2. 80 
19. 65 
22.45 
4.5 
95.5 
Yahara 
July 
6, 1922 
0 
1. 19 
(>) 
(>) 
2. 32 
18. 54 
20. 86 
1 Not determined. 
4469&— 27 14 
