367 
The production in the lake during this period is greater 
than that in-the river at all times of coincident examination 
excepting March 14 (.14 and .35). The average production in 
the lake (.67 cm.*) is 63 per cent. greater than that in the river 
(.41 cm.*). This percentage of increased production is a meas- 
ure, or an index, of the impounding or reservoir action of the 
lake under the hydrographic conditions of these months. . The 
immediate result of the access of Quiver Lake waters to the 
channel will be a rise in its plankton content from .41 em.’ per 
m.’ to .414—an increase of 1 per cent. 
The summary of the interrelations of production in this 
lake and the river will be made in conjunction with that of Dog- 
fish Lake, which is only an arm of Quiver Lake. 
DOGFISH LAKE, 
(Table VI.; Pl. XVIIL., XXX., XXXII.) 
ENVIRONMENTAL CONDITIONS, 
This so-called lake is only the westerm arm of Quiver Lake 
(Pl. IL.), separated from the eastern by Quiver Point, a low 
marshy spit covered with rushes and willows and lying but a 
few feet above low-water mark. It is of elliptical form, about 
three quarters of a mile long and one third of a mile wide, 
contains about 150 acres at low water, and as levels rise it ex- 
tends northward and eastward over the low bottoms towards 
Mud Lake and Cartwright Slough, but it is only at highest 
levels that very much of a current makes its way down through 
this lake. As levels rise above 8 ft. the intervening ridge sep- 
arating this lake from the river is gradually submerged, and 
channel waters invade more or less of the lake. — It affords the 
natural channel for the run-off of the backwaters impounded 
in several square miles of bottom-land marsh and forest 
through the swale (Pl. II.) which extends towards Mud Lake. 
Its shores are everywhere low and marshy, of black alluvi- 
um, and a soft black ooze of similar origin covers the bottom of 
the entire lake. In only a limited area towards the east- 
