364 
a slight but not equal rise (.10) in channel production. The 
March pulse in the river, with a maximum amplitude of .77 on 
the 22d, is attended by almost equal production in the lake (.67). 
The vernal pulse rises with like abruptness at both stations, 
increasing from April 1 to May 3 from 1.03 to 42.14 in the 
lake, and from 1.12 to 35.68 in the river. The decline of this 
pulse is much more abrupt in the lake, falling from 42.14 on the 
3d to 4.7 on the 11th—a decrease of 89 per cent. in 8 days, while 
the decline in the stream is from 35.68 to 10.31, or 71 per cent., 
in 7 days. The more abrupt change in the lake plankton is due 
to the fact that the decline in levels of 1. ft. in the interim be- 
tween the two collections compared, is at the critical point ap- 
proaching bank height, when the bottom-lands to the north of 
Quiver Lake are beginning to emerge and cut off and divert 
some of the run-off of the impounded backwaters which at higher 
levels make their way tothe channel through Quiver Lake (PI. I1.). 
There is a very slight July pulse in the lake on the 19th 
coincident with the July maximum in the river. Inthe early 
part of August there is another maximum in the river, but no 
parallel developement in the lake, owing possibly to the low 
water then attained and the resulting dominance of vegetation 
and tributary waters—conditions not incident to these levels 
in like degree in channel waters. The rise at the close of August 
and again in September, and the low level and slight change in 
production in October found in channel waters are all to be 
traced coincidently, or approximately so, in the less complete 
records of the lake production. 
The silt-laden flood waters which cause rising levels in No- 
vember deplete the channel plankton (.25), increase the im- 
pounding function of the lake, and lead to greater production 
(.73) in the latter. There are coincident culminations in river 
and lake on Dec. 6, but the interval of collection in the lake 
does not permit comparison in case of the river maximum of 
Dec. 20. The large December production (1.74), six to eleven 
times that of July (.16), August (.22), September (.33), or Oc- 
* tober (.23) is noteworthy. 
