378 
BULLETIN OF THE BUREAU OF FISHERIES. 
In the lower part of the river the fluctuations in the amount of plankton are 
insignificant, and samples taken there contain detritus almost exclusively. The 
waters of the tributaries of the Mississippi River carry a great quantity of detritus, 
and the amount of the material suspended in them sometimes is exceedingly great, 
as it was, for instance, in Turkey River, where the volume of sediment in suspension 
reached 0.9 cm. 3 per 100 cm. 3 of water or 9,000 cm. 3 per cubic meter. This ob- 
servation was made on September 14, when the river was rising. The results of 
the determination of the amount of plankton found in the tributaries are given in 
Table 24. 
Table 14. — Volume of plankton — Mississippi River between Hastings, Minn., and Alexandria, Mo. 
Station. 
Near Hastings 
Near Prescott 
Diamond Bluff 
Near Red Wing 
One mile above head of Lake Pepin: 
Right bank 
Main channel 
Left bank 
Above mouth of Chippewa River: « 
Right bank 
Midstream 
Left bank 
Reads Landing: 
Right bank 
Midstream 
Left bank 
One mile above Wabasha, main channel 
Beef Slough 
Opposite mouth of Zumbro River 
Between Winona, and Homer, main channel 
Four miles above La Crosse: 
Main channel 
Right bank 
Slough near Light No. 98 
Opposite mouth of Root River, main channel 
Between De Soto and Lansing, main channel 
Three miles above Prairie du Chien, main channel... 
Prairie du Chien: 
East channel, midstream 
East channel, left bank 
McGregor, main channel 
Opposite mouth of Wisconsin River, main channel. . 
One mile below Cassville, main channel 
Four miles below Bellevue, main channel 
Six mil es above Clinton, main channel 
Three miles below Clinton, main channel 
Rock Island Rapids 
One mile below mouth of Rock River, main channel. 
Fairport: 
Main channel 
Andalusia Slough 
Do 
Main channel 
Below the dike 
New Boston: 
Main channel 
Sturgeon Bay 
Midstream 
One mile below mouth of Edwards River: 
Midstream 
Main channel 
Two miles below Burlington, main channel 
Alexandria, main channel 
Serial 
number 
of 
station. 
Date. 
Volume 
of 
plankton, 
cubic 
centi- 
meters 
per cubic 
meter of 
water. 
Serial 
number 
of 
station. 
Date. 
Volume 
of 
plankton, 
cubic 
centi- 
meters 
per cubic 
meter of 
water. 
116 
Sept. 1 
12.3 
115 
. ..do 
16.3 
111 
...do 
22.7 
110 | 
. ..do 
21.5 
98 
Aug. 29 
17.0 
97 
. ..do 
17.5 
96 
. ..do 
15.3 
104 
Aug. 30 
21.5 
105 
...do 
18.0 
106 
. ..do 
33.0 
101 
...do 
22.5 
124 
Sept. 10 
14.6 
102 
. ..do 
24.0 
103 
...do 
19.0 
57 
Aug. 9 
18.5 
125 
Sept. 10 
10.0 
127 
. ..do 
11.7 
128 
Sept. 11 
21.5 
129 
. ..do 
21.0 
131 
. ..do 
18.0 
130 
. ..do 
17.5 
135 
Sept. 12 
136 
ioi o 
55 
Aug. 15 
28.7 
137 
Sej)t. 13 
17.0 
54 
...do 
32.0 
138 
Sept. 14 
17.3 
139 
. ..do 
11.0 
141 
. .do. 
16.7 
53 
Aug. 14 
25.8 
143 
...do 
16.5 
145 
Sept. 15 
14.7 
146 
Sept. 16 
10.7 
51 
Aug. 12 
15.7 
147 
Sept. 17 
7.3 
50 
Aug. 11 
6.0 
148 
...do 
6.0 
150 
Sept. 18 
7.0 
2 
July 12 
6.0 
1 
July 11 
4.0 
4.7 
Aug. 9 
6.6 
48 
. ..do 
4.3 
49 
...do 
3.3 
4 
July 13 
6.75 
3 
...do 
5.0 
151 
Sept. 20 
3.0 
5 
. ..do 
3.7 
7 
. ..do 
6.0 
153 
Sept. 20 
6.3 
154 
...do 
3.75 
157 
Sept. 23 
3.0 
