267 
point of collection the run of driftwood in the stream exhibited 
no marked difference in current in the channel for an extent 
of fully 400 feet. Approximately uniform conditions thus pre- 
vail over a considerable extent of the river channel at this 
point. At high water (Pl. III.) the banks are submerged, but 
aside from increased rapidity and some lateral extension there 
is no noticeable difference in the conditions of the current. 
MODIFICATIONS OF METHODS AT THIs STATION. 
Collections made by the oblique-haul method were always 
taken on the western side of the stream, across the current 
from a point in deep water, the surface end of the haul being 
completed in shoaler water. At times of high water it was 
necessary, both on account of the strength of the current 
and the depth, to shift the apparatus still more towards the 
shore, and, finally, in the flood of December, 1895, to abandon 
the method and substitute temporarily a series of four to six 
vertical hauls, amounting to about 30 meters—the usual dis- 
tance of the oblique haul. These were made in midstream 
from a floating or anchored boat, and were continued from De- 
cember 27, 1895, to May 20, 1896. After the adoption of the 
pumping method on the latter date the boat or launch was at 
first allowed to drift with the current while the collection was 
made. Owing to frequent difficulty caused by the drifting of 
the boat into shallow water by the wind before the catch was 
completed, we finally adopted the plan of anchoring the boat 
or launch in or near the mid-channel while the collections were 
being made. 
During the winter season, owing to air-holes and weak 
places caused by the irregular melting of the ice upon the low- 
er surface, the ice on the river channel was rarely firm enough 
to permit safe transit of our plankton outfit, whose total 
weight was over 800 pounds. Steel runners were placed upon 
the bottom of the boat, and by the aid of ice hooks it was pos- 
sible to run over or to break one’s way through thin or 
rotten ice to the mid-channel station, where open stretches of 
